Practical Process Plant Layout and Piping Design
Practical Process Plant Layout and Piping Design
Practical Process Plant Layout and Piping Design
STUDENT LOGIN
(HTTPS://MOODLE.EIT.EDU.AU/LOGIN
/INDEX.PHP)
INSTRUCTOR LOGIN
(HTTPS://MOODLE.EIT.EDU.AU/LOGIN
/INDEX.PHP)
(/index.php)
Contact Us
(/cms/course-
Search ... enquiry)
Rev 5.1
Website: www.idc-online.com
E-mail: idc@idc-online.com (mailto:idc@idc-online.com)
All rights to this publication, associated software and workshop are reserved. No part of this publication may be
reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, mechanical,
photocopying, recording or otherwise without the prior written permission of the publisher. All enquiries should be
made to the publisher at the address above.
Whilst all reasonable care has been taken to ensure that the descriptions, opinions, programs, listings, software and
diagrams are accurate and workable, IDC Technologies do not accept any legal responsibility or liability to any person,
organization or other entity for any direct loss, consequential loss or damage, however caused, that may be suffered
as a result of the use of this publication or the associated workshop and software.
In case of any uncertainty, we recommend that you contact IDC Technologies for clarification or assistance.
All logos and trademarks belong to, and are copyrighted to, their companies respectively.
IDC Technologies expresses its sincere thanks to all those engineers and technicians on our training workshops who
freely made available their expertise in preparing this manual.
Prelim i-x
1.2 Procedures and workflow methods used in plant layout and piping design 6
1.3 Physical quantities and units in plant layout and piping design 9
1.4 Summary 12
Practical Exercise 1 13
2.3 Summary 27
Practical Exercise 2 28
3.1 Introduction 31
3.4 Summary 51
4.3 Summary 65
5 Piping and Instrumentation Diagrams (P&IDs), Control Valve Manifolds, Meter Runs 69
5.1 Piping and instrumentation diagrams (P&IDs) and their role in process plant layout and piping design 69
5.5 Summary 78
6.11 Summary 98
Practical Exercise 6 99
This chapter provides a brief introduction to Process Plant Layout and Piping Design. The fundamental
aspects of process plant layout and piping design are discussed. An overview of the procedures and
workflow methods used in plant layout and piping design is also provided and the physical quantities and
units commonly used are presented.
Understanding the fundamental aspects of process plants, plant layout and piping design.
Understanding the procedures and the workflow methods used in designing process plants and piping systems.
Understanding the physical quantities and units used in process plant layout and piping design.
Process plants encompass all types of facilities involved in the chemical/physical processing of raw materials into
desired finished products or intermediates for further processing. Examples of such processing facilities include the
following:
Refineries.
Chemical/Petrochemical Plants.
Fertilizer Plants.
Offshore Processing Facilities.
Power Plants.
Pulp and Paper Mills.
The processing facilities included in the preceding list play a vital role in meeting the basic needs of humanity.
Therefore, a proper design, maintenance and operation of such facilities is necessary to ensure steady, dependable
supply of materials and products required for comfortable and productive living in the contemporary modern world.
Process plants are complex facilities consisting of equipment, piping systems, instruments, electrical systems,
electronics, computers and control systems. Figure 1.1 is a picture of a section of a refinery that illustrates the
complexity of the equipment, piping and other entities.
Figure 1.1
A small section of a refinery showing equipment, piping system and other items.
The design of process plants is a complex team effort involving different disciplines of engineering: process (chemical),
mechanical, piping, electrical, instrumentation, controls, materials and project. It also requires considerable
management and coordination skills.
The objective is to design and construct a plant in a cost-effective manner that will meet the process requirements and
client specifications and that will operate in a safe reliable manner. Other factors to be considered in the design of
process plants are:
Short design, engineering and construction schedules and getting the plant on stream as quickly as possible.
Minimizing or even eliminating field rework, which significantly increases plant construction costs.
Constructability.
Maintainability.
Operability.
Satisfying environmental requirements.
5 de 136 30/08/2019 16:12
Practical Process Plant Layout and Piping Design https://www.eit.edu.au/cms/resources/books/practical-process-plant-la...
Minimizing costs.
Figure 1.2 illustrates the interaction and teamwork between different disciplines in the plant layout and piping design
effort.
Figure 1.2
Plant Design and Piping Design Effort – Contributions from different disciplines
Development and refinement of “Plot Plans”. Plot plans are representations of precise location of equipment and
their associated infrastructure (foundations, ladders, platforms etc.). Plot plans are developed taking into
consideration process, client and safety requirements. Plant coordinates are used extensively in specifying
equipment locations. Plot plans are discussed in more detail in Chapter 4.
Establishing equipment nozzle locations. Nozzles are components of equipment that connect to pipe.
Routing of pipes. This is a dynamic and iterative process until the equipment and nozzle locations are finalized.
Designing equipment ancillaries such as foundations, platforms, and stairways.
Location of safety equipment such as fire hydrants and safety showers.
Being cognizant of the location of structures, instruments, control valves, electrical raceways and miscellaneous
plant items while routing pipe.
Sufficient knowledge of the process being used including function of each equipment. This information is obtained
from the process group in the form of “Process Flow Diagrams (PFDs)”. PFDs are discussed in detail in Chapter 2.
6 de 136 30/08/2019 16:12
Practical Process Plant Layout and Piping Design https://www.eit.edu.au/cms/resources/books/practical-process-plant-la...
Knowledge of the operating and maintenance procedures used for equipment.
Common sense and attention to detail.
Ability to think creatively to solve layout problems and challenges.
Ability to think and visualize spatial relationships between plant items in three dimensions.
Ability to effectively use computer tools such as 3D modeling software and pipe stress analysis software.
Excellent communication skills.
Ability to function effectively as a member of a multi-disciplinary project team.
Effectively communicate and resolve layout issues and problems with project management.
Ability to produce, maintain and update project drawings and documents.
Awareness that conscientious, quality effort during the design and engineering phase can shorten project
schedules resulting in economic benefits and client goodwill.
Massive amounts of data is generated and used in plant layout and piping design. Proper management of plant data is
necessary to ensure data accessibility and data integrity, which in turn contributes to the overall quality of the project.
Plant data can be classified into three categories.
Project data consists of information such as plant location, local codes and regulations, access roads, waterways,
railways, seismic conditions, climate data (average temperature, wind speed and direction, and rainfall).
Design and engineering data is internally generated during the design and engineering phases of the project.
Examples of such data include equipment sizes, service conditions (temperature, pressure etc.), and mass flow
rates.
Vendor data consists of information provided by equipment vendors by means of vendor drawings and data
sheets.
The approach to plant layout and piping design can vary depending on the nature of the plant and the project. For
example, the design philosophy for an offshore facility is quite different from that for an onshore chemical plant simply
because of limited space available on offshore platforms. However, there are a few useful rules of thumb that can be
followed.
Abbreviations used in PFDs and P&IDs are explained in Chapters 2 and 5 respectively.
Front end engineering and design: The complex task of designing and building process plants consists of several
phases – design, engineering, procurement and construction. The design phase itself consists of conceptual design,
design study and detailed design. The conceptual design phase starts with the Process Flow Diagram (PFD) and client
specifications. The project scope is also defined during this phase. The working documents used during this phase are
the PFD and the Conceptual Plot Plan. Based on the PFD, a large chemical plant or offshore production facility is sub-
divided into several small, manageable areas. A Plot Plan is then generated for each area. Boundary limits for each
area are specified using spatial coordinates. The boundaries are known as match lines and play an important role in
combining the smaller areas. In offshore platforms, plot plans are generated for each deck of the platform. The
outcome of the conceptual design phase is usually preliminary sizes and locations of major equipment, which results in
the plot plan for use during the design study phase.
The design study phase plot plan is reviewed and discussed by the client and by the project disciplines. Vessel
supports and ancillaries are located during this phase. Preliminary routing of major lines also takes place during this
phase. The outcome of the design study phase is a final plot plan and a preliminary Piping & Instrumentation Diagram
(P&ID). The P&ID contains details and specifications of all equipment, piping, fittings, instrumentation and control
valves. The P&ID also contains references to detailed drawings of equipment. The P&ID serves as the primary
reference document in communication between engineering and design personnel in all disciplines. Thus, the P&ID is
an important working document in the design and engineering of process plants and piping systems. The final plot plan
and the P&ID must be approved by all disciplines including safety and loss control.
The conceptual design and design study phases together constitute the Front End Engineering and Design (FEED)
phase of the project. The P&ID, plot plans and elevations are used in building a three dimensional electronic model of
the process plant. This 3-D model will contain all the components of the plant including equipment, piping, fittings,
control stations and support structures. In recent years, the ability to build 3-D electronic models has been greatly
enhanced due to advancements in computer hardware and software.
Detailed design and engineering: The FEED phase is followed by the detailed design and engineering phase where
8 de 136 30/08/2019 16:12
Practical Process Plant Layout and Piping Design https://www.eit.edu.au/cms/resources/books/practical-process-plant-la...
every piece of equipment and every component of piping systems is finalized and specified for procurement. During
this phase, piping isometric drawings known as “Issued-For Design (IFD)” drawings are generated for analysis and
comment by piping engineers and engineers from other disciplines whose input is required. The IFD drawings are
pictorial representations of the piping system and allied components containing all dimensional information. Piping
engineers primarily use the IFD drawings for the following purposes:
Pipe Stress Analysis: The piping systems are analyzed for stress and load to ensure that the pipes are not
overstressed (both under installed and operating conditions) and are adequately supported. In many cases, piping
systems need to have enough flexibility to allow for thermal expansion. Pipe stress analysis also includes
computing loads and stresses on equipment nozzles and ensuring that they are within the allowable limits specified
by applicable standards and codes. Pipe stress analysis is performed with the aid of stress analysis software.
Code compliance: The code that governs the design of piping systems for process plants is ASME B31.3: Process
Piping. Piping engineers are responsible for interpreting the code using sound engineering judgment to ensure that
the proposed design meets the code requirements.
Piping material specifications: The piping engineer is responsible for specifying appropriate materials for the pipes.
In accomplishing this task, the piping engineer takes into account operating conditions such as the pressure and
temperature and also the chemical nature of the fluid being transported. Piping material specification is a very time
consuming task but it is very important to specify the right material to ensure the safe and efficient operation of the
plant.
The 3-D model is an extremely useful design tool that can be used by all disciplines during the detailed design and
engineering phase. The 3-D model is constantly referenced during design review meetings and discussions. These
meetings occur frequently and involve all the engineering disciplines and the client. The 3-D model is also useful in
clash detection and interference checking. This process saves considerable money and effort by minimizing field
rework and field rerouting of pipes. An engineering database is also generated as part of the electronic model. This
database is useful in purchasing and procurement functions. As the design is reviewed and updated, so is the 3-D
model.
After the detailed design and engineering phase, piping isometric fabrication drawings (also known as spool drawings)
along with material specifications are issued for creating the required piping spools. Simultaneously, procurement lists
are generated for fittings, instrumentation and other items in the piping system from the engineering database. The
procurement lists are used for purchasing the items and contain all the information required to accomplish this task.
The procurement lists are also known as “Bill of Materials (BOM)” or “Material Take-off”.
Foundations, structural members and major equipment are put in place using civil/structural drawings, equipment
drawings, the 3-D model and other documents. Now the stage is set for the installation of the piping system. Drawings
and documents known as “Issued for Construction (IFC)” are used for this purpose. Construction personnel assemble
and install the piping system by using IFC drawings and documents.
Figure 1.3 illustrates the workflow methods used in process plant layout and piping design. It should be noted that
workflow methods could vary depending on client and company preferences. It should also be noted that the entire
process is iterative in nature. There is continuous interaction between the different phases of the project.
Figure 1.3
Procedures and Workflow Methods Used in Plant Layout and Piping Design
Some of the organizations that provide standards and guidelines for plant layout and piping design are listed here
along with their web addresses.
American Society for Mechanical Engineers (ASME): Publishes and updates codes for piping design. The code
relevant to the design of piping systems is ASME B31.3 – 2004 Process Piping. (www.asme.org)
The physical quantities and units used in plant layout and piping design are summarized in Table 1.1. The units are
specified both in the SI System and in the US Customary System (USCS).
Table 1.1
Physical Quantities and Units Used in Plant Layout and Piping Design
Physical
Symbol SI System USCS
Quantity
Length L Meter (m) Feet (ft)
Diameter D Millimeter (mm) Inch (in)
Thickness Δx Millimeter (mm) Inch (in)
Mass m Kilogram (kg) Pound mass (lbm)
Time t Seconds (s) Seconds (sec)
Temperature T Degree Celcius (°C) Degree Farenheit (°F)
2
Area A Square meter (m ) Square feet (ft2)
Volume V Cubic meter (m3) Cubic feet (ft3)
Velocity v Meters/sec (m/s) Feet/sec (ft/sec)
Acceleration a Meters/sec2 (m/s2) Feet/sec2 (ft/sec2)
Force F Newton (N) Pound force (lbf)
Pressure P Pascal (Pa) Pounds/in2 (psi)
Stress s Megapascal (Mpa) Pounds/in2 (psi)
Strain ɛ Mm/mm in/in
Work W Newton-meter (N.m) Foot pound force (ft-lbf)
Energy E Joule (J) British thermal unit (Btu)
Energy flow kilowatts (kW) Btu/sec or Btu/hr
Enthalpy H kilojoules (kJ) Btu
Mass flow kg/s Lbm/sec
Volume flow m3/s ft3/sec
Notes: The unit of force in the SI system is Newton (N). A Newton is defined as the force required to produce an
acceleration of 1 m/s2 on a body of mass 1 kg. The unit of force in the US Customary System (USCS) is Pound force
(lbf). One pound force is the force required to accelerate 1 lbm at 32.2 ft/sec2. This leads to the use of a conversion
Figure 1.4
Workflow model
1. What are the main tasks of a plant layout designer? (Name just three)
3. Besides the design and engineering phases of a project, what other aspects of the project should a good designer
be concerned about? Explain.
A. IFD:
B. TOS:
C. PFD:
D. ANSI:
5. Psi stands for ______________ and is a unit of _____________ and kPa stands for _____________.
8. What are the possible consequences of not knowing maintenance requirements for a particular piece of equipment?
This chapter provides an overview of the processes used in chemical/petrochemical and other facilities.
Process Flow Diagrams (PFDs) are also discussed in this chapter.
The chemical process industry primarily comprises processing raw materials such as crude oil and natural gas into
finished products such as gasoline (petrol), aviation fuel, cooking gas, fertilizers and polymers to meet the needs of
consumers. Chemical processing principles are also used in the production of processed foods and medicines, in
water and wastewater treatment, and in pollution control. Thus, the chemical process industry plays a major role in
meeting the basic needs of humanity viz., food, shelter, clothing, medicine and transportation. Some products of the
chemical industry enter the market as consumer goods while others are intermediates used in the manufacture of
consumer items. Considering the great variety of useful products produced by the chemical industry, it touches our
lives like no other industry. Chemical and allied industries create and synthesize products and in this sense are
different from many manufacturing industries that assemble products. The chemical industry accomplishes the
transformation from raw materials to finished products through a series of chemical and physical changes.
Understanding the chemical process technology requires an understanding of the processes that are used in bringing
about chemical and physical changes during commercial production. The study of the great number and the vast
variety of chemical and physical changes used in the chemical process industry is greatly simplified by organizing the
changes into unit operations and unit processes. A comprehensive understanding of technologies used in chemical
processing also requires knowledge of the scientific and engineering principles used in the development and use of
such technologies.
Chemical processing consists of a sequence of steps some of which may involve only physical changes. Operations
that accomplish physical changes in the material being processed are called unit operations. For example, the process
used in manufacturing common salt consists of the following sequence of unit operations: transportation of solids and
liquids, transfer of heat, evaporation, crystallization, drying and finally screening. Unit operations are identical in
fundamental principles regardless of the material being processed. By systematically studying these operations, which
clearly cross industry and process lines, the treatment of all processes can be unified and simplified. Physical and
mathematical models developed for each unit operation can be applied across a broad spectrum of chemical industry.
Some important unit operations, their application and equipment used are described here.
Distillation: Distillation is the process of separation of components by using the differences in their boiling points. The
more volatile component (with a lower boiling point) vaporizes first and is condensed. Distillation is widely used in the
chemical process industry. A very important application is the atmospheric distillation of crude oil used in the petroleum
Drying of solids: The unit operation here is the removal of moisture. Typical equipment used in drying are spray
driers, rotary driers and tunnel driers. Each of these is described below with examples of applications in the chemical
process industry.
The spray drier is suitable for large capacity operation of liquid feed to give powdered, spherical, free flowing
product. Spray driers are used in production of pigments, detergents, synthetic resins and inorganic salts.
The rotary drier is suitable for drying free flowing granular solids that do not stick. High temperature rotary kilns are
used in the manufacture of cement.
The tunnel drier is used in drying pastes or powders in trays. It is also used in drying pottery, lumber and leather in
sheet or shaped forms.
Evaporation: Evaporation is used in increasing the concentration of a solution by vaporizing a portion of the volatile
solvent; usually water. The feed is a dilute solution and the product is a concentrated solution. Evaporation is used in
the production of sugar and common salt. It is used in thickening the liquor in paper mills and also in producing potable
water from seawater. Evaporators consist of vessels with a bank of tubes. The material to be concentrated flows inside
the tubes and the heat required is generated by steam condensing on the outside of the tubes. The design of
evaporators involves the principles of heat transfer and mass and energy balances. In a single-effect evaporator, the
vapor from the boiling liquid is condensed and discarded. In a multiple-effect evaporator, the vapor from the first
evaporator is fed into the steam chest of the second evaporator; the vapor from the second evaporator is fed into the
steam chest of the third evaporator and so on. Multiple-effect evaporators decrease the consumption of steam
required.
Gas absorption: In gas absorption, a liquid solvent absorbs one of the components in a mixture of gases. An example
of gas absorption is absorption of ammonia from a mixture of ammonia and air using water as the solvent. This
technique is also used in the removal of hydrogen sulfide from hydrocarbons. A common apparatus used in gas
absorption is the packed tower. The device consists of a cylindrical tower, equipped with a gas inlet and distributing
space at the bottom and a liquid inlet with a distributor at the top. The outlets for the liquid with the solute gas and the
lean gas are located at the bottom and top respectively, thus achieving a counter flow of the liquid and gas streams. A
mass of inert solid shapes forms the core of the tower between the inlet and outlet streams. This packing promotes
intimate contact between the liquid and gas phases. The design of the absorption tower uses the principles of diffusion
and mass transfer. The reverse process of gas absorption is known as desorption or gas stripping. In this case the
solute is removed from the liquid solvent by contacting it with an inert gas. The pure solvent is then recycled and
reused for gas absorption.
Liquid-liquid extraction: In this unit operation, one constituent from a liquid mixture is removed by using a liquid
solvent. The liquid phase containing the solute and the solvent is known as the ‘extract’ whereas the liquid phase with
the solute removed is known as the “raffinate”. As an example, naphthenes are removed from lube oil fractions using
furfural as a solvent. Typical equipment used in liquid-liquid extraction includes a battery of mixers and settlers, packed
columns and towers with mechanisms for agitation of the liquid phase to promote intimate contact.
Leaching: In leaching, a solvent is used in removing a soluble component from a mixture in the solid phase. This
Crystallization: Crystallization is the formation of solid particles from a homogenous phase. Since a variety of
materials are marketed in crystalline form, crystallization from solution is an important chemical processing technique.
Crystallization is a very useful method for producing pure chemical substances in a satisfactory condition for packing
and storing. It needs to be noted that pure crystals can be formed even from an impure solution. The process of
crystallization is used in the production of common salt, sugar, dyes and pigments. Crystallization equipment can be
classified into the following three categories:
Tank crystallization – Here, super-saturation is achieved by cooling hot, saturated solutions. The cooling is
achieved by natural convection and can be enhanced by cooling coils or cooling jackets.
Evaporator-Crystallizers – Here, super-saturation is achieved by evaporation.
Adiabatic Vacuum Crystallizers – Here, super-saturation is achieved by evaporation combined with adiabatic
cooling, which causes nucleation and growth of crystals.
Filtration is used in separating solids from solutions. Examples of this operation are separation of minerals from
slurries and pulp fibers from thick liquor in paper mills. Typical equipment used in filtration are rotary drum filters
and filter press.
Removal of particulate solids from gases is used in controlling air pollution and in cutting down product losses.
Typical equipment used in achieving these are cyclone separators, electrostatic precipitators wet scrubbers.
Centrifugation is used in separating very finely divided solids from liquid or liquids from liquid emulsions. This is
achieved by the use of rotating centrifuges.
Membrane Separation uses a semi-permeable membrane to achieve separation. This technique is used in dialysis
where caustic is separated from sugar or cellulose due to the wide difference in molecular weights. Micro-porous Ni
barriers are used in separating light uranium compounds from heavy uranium compounds, since the light
compounds diffuse through the membrane or barrier.
Just as unit operations are useful in the systematic study of physical changes, the concepts of unit processes can be
used in systematizing chemical changes or reactions found in chemical industries. The advantage is that prior
performance data from a group of chemical reactions can be applied to the production of other chemicals using similar
unit processes. As an example, nitration is a commonly used unit process. The nitration reaction is an exothermic
reaction and has certain characteristics of reaction rates and reaction equilibrium. This data has led to the design for
nitration reactors. These reactors are typically liquid phase reactors made of cast iron with provision for mixing of
reactants and for heat removal. Similar designs can be used for other nitration reactors. Listing all unit processes used
in the chemical industry is beyond the scope of this course manual. A few commonly occurring unit processes and
their applications are described in the following paragraphs.
Alkylation: Alkylation is a unit process where an alkyl radical (-CH3) is added to a reactant. An example is alkylation
of butylene in the presence of heat and catalyst to produce iso-octane, which is an important additive for gasoline.
Combustion: Combustion is burning of fuel where the fuel reacts with oxygen to form combustion products. More
importantly, the heat released during combustion is used in process heating and in power generation.
Condensation: Condensation is a chemical reaction where water is one of the products. Condensation reactions are
widely used in the manufacture of organic chemicals, dyestuffs and synthetic perfumes.
Esterification: Esterification is the reaction of an organic acid with alcohol to produce esters or organic salts. This
reaction is used in manufacture of soaps and oils.
Halogenation: Halogenation is addition of chlorine molecule and is used in the production of organic chemicals.
Isomerization: Isomerization is used in changing the structural formula of organic compounds from straight chain to
branched structure and is used in petroleum refining.
Polymerization: Polymerization reactions are used in building large polymer macromolecules. There are two types of
polymerization reactions - addition polymerization and condensation polymerization. Polymerization reactions are used
in the manufacture of plastics and synthetic fibers.
Chemistry: The principles of chemistry are essential for understanding the basis of chemical reactions involved in
chemical processing. Balanced chemical equations are important in calculating the yield of products.
Mass and energy balances: The principles of mass and energy balances are used in sizing of equipment for
processes and also in determining energy requirements (heat addition or removal) for processes. Mass and energy
balance calculations are used in monitoring the flow of material and energy through different units in any chemical
plant. This involves the synthesis and analysis of Process Flow Diagrams (PFDs).
Fluid mechanics: In chemical processing, fluids must be transported between process units and different equipment.
Fluids are typically transported in pipes. The principles of fluid mechanics are used in the design of piping systems in
chemical process industries. Piping systems include pipes, fittings, valves, pumps and ancillary equipment. Important
considerations in the design of piping systems are fluid properties (density, viscosity), fluid velocity and pressure and
elevation differences. Principles of fluid mechanics are also used in measurement of pressure and flow rates of fluids.
Pumps are used in providing the required energy for fluid transport. The most commonly used pump is a centrifugal
pump.
Heat transfer: Addition or dissipation of heat is a common feature in the chemical industry. The principles of heat
transfer are used in the design of heat exchangers, heating coils, furnaces, fired heaters, condensers, reboilers and
jacketed vessels.
Reaction kinetics: The principles of reaction kinetics are used in the design of chemical reactors and in the prediction
of reaction rates, reaction conversions and the time required to achieve a particular level of conversion. Chemical
reactors are classified as homogeneous (single phase) and heterogeneous (multiple) and further into batch reactors,
stirred tank reactors and tubular reactors.
Mass transfer: The principles of mass transfer and diffusion are used in the design of equipment such as distillation
columns, absorption towers, dryers and ion-exchange units.
Process control and instrumentation: Appropriate instrumentation and communication methods are necessary to
monitor the status of a given process. Proper control strategies and methods are essential in maintaining process
variable within reasonable limits and also in ensuring process safety. An important tool in the synthesis of
instrumentation and control strategies is the Process & Instrumentation Diagram (P&ID).
Process flow diagrams (PFDs) are schematic representations of process plants that provide an overview of all the
processing steps (unit operations and unit processes) used in process plants.
All major equipment used in the plant. Equipment can be classified as Process Equipment (Reactors, Towers,
Exchangers) and Mechanical Equipment (Pumps, Compressors, Blowers).
Stream information and flow directions. Streams within a process plant can be classified into Material Streams
and Energy Streams. Material streams show the flow of reactants, products and other fluids in the plant while
energy streams show the flow of heat energy.
Mass flow rates, compositions, temperature, and phase fraction (liquid or vapor) of each material stream.
Energy (heat) transfer rates.
Sometimes, the preceding information is presented in the form a “Stream Summary Table” instead of indicating it
on the PFD.
Figure 2.1
Icons Commonly Used in Process Flow Diagrams (From: Product & Process Design Principles, Warren
Seider et al., 2nd ed., John Wiley and Sons, 2004)
Figure 2.2 shows the PFD for the manufacture of vinyl chloride using chlorine and ethylene as raw materials. Vinyl
chloride is an important product since it is used in the manufacture of polyvinyl chloride (PVC). This manufacturing
process involves three major steps.
Figure 2.2
Process Flow Diagram for the Manufacture of Vinyl Chloride (From: Product & Process Design Principles,
Warren Seider et al., 2nd ed., John Wiley and Sons, 2004)
Table 2.1 gives typical information on different streams in the PFD for the manufacture of vinyl chloride.
Table 2.1
Stream Information Table for PFD in Figure 2.2
Stream Number 1 2 3 4
Temperature
25 25 90 90
(°C)
Pressure
1.5 1.5 1.5 1.5
(Atm)
Vapor Fraction 1.0 1.0 0.0 0.0
Mass Flow
20 410 51 545 71 955 1 19 910
(kg/hr)
Component Mole Fractions
Ethylene
Chlorine 1 0 0 0
Ethylene 0 1 0 0
dichloride 0 0 1 1
Vinyl chloride 0 0 0 0
Hydrogen 0 0 0 0
Chloride
Stream Number 5 6 7 8
Temperature
91.3 242 500 170
(°C)
Stream Number 9 10 11 12
Temperature
6 6.5 -26.4 94.6
(°C)
Pressure
26 12 12 12
(Atm)
Vapor Fraction 0.0 0.0 1.0 0.0
Mass Flow
1 19 910 1 19 910 26 500 93 410
(lbm/hr)
Component Mole Fractions
Ethylene
Chlorine 0 0 0 0
Ethylene 0 0 0 0
dichloride 0.25 0.25 0 0.4
Vinyl chloride 0.375 0.375 0 0.6
Hydrogen 0.375 0.375 1 0
Chloride
Stream Number 13 14 15 16
Temperature
57.7 32.2 145.6 90
(°C)
Pressure
4.8 4.8 4.8 4.8
(Atm)
Vapor Fraction 0.23 0 0.0 0.0
Mass Flow
93 410 45 455 47 955 47 955
(lbm/hr)
Process utilities: All process plants require utilities such as steam and cooling water. The primary purpose of utilities
is heating and cooling of process streams. Heating is accomplished by using steam. Cooling is accomplished by using
cooling water and refrigerants. Table 2.2 lists the pressure and temperature ranges for utilities used in process heating.
The utilities are listed in the order of increasing cost per kJ of heating. Table 2.3 lists utilities used in process cooling in
the order of increasing cost per kJ of cooling.
Table 2.2
Pressure and Temperature Ranges for Heating Utilities
Utility Pressure Range (kPa) Temperature Range (°C)
Low Pressure Steam (LPS) 200 to 300 120 to 140
Medium Pressure Steam (MPS) 700 to 1400 160 to 190
High Pressure Steam (HPS) 2700 to 4200 230 to 260
Petroleum Oils (PO) Below 320
Dowtherm (DT) Below 400
Table 2.3
Utilities Used in Cooling
Utility Description
Air Cooling (AC) Supply at 30°C, ΔT = 5°C to 10°C
Cooling Water (CW) Supply at 25°C, ΔT = 10°C to 15°C
Chilled Water (CHW) ΔT = 25°C to 50°C
Refrigerated Brine (RB) Cooling in the range of 10°C to –18°C
Propane Refrigerant (PR) Cooling in the range of -6°C to –40°C
Equipment: Different types of process and mechanical equipment are used in process plants. They include vessels,
towers, heat exchangers, fired heaters, pumps and compressors. Proper specification of equipment is an important
task in process plant layout and design. Specifications required for each type of equipment are summarized in Table
2.4.
Table 2.4
Summary of Equipment Specifications
Equipment Specifications Required
Vessels Pressure, Temperature, Height, Diameter, Materials of Construction, Orientation.
Pressure, Temperature, Height, Diameter, Materials of Construction, Orientation, Number and type of
Towers
trays, Height and Type of Packing.
Type, Duty, Tube Pressure and Temperature, Materials of Construction, Radiant and Convective Heat
Fired Heaters
Transfer Areas.
In this chapter, the basic principles of chemical technology have been discussed. Unit Operations and Unit Processes
typically used in process plants have been described. Process Flow Diagrams (PFDs) and the information presented in
PFDs have been discussed at length.
Given the attached PFD and the process description for the production of vinyl chloride:
EDC vapor at a pressure of 4 atm. is dried by using a silica gel drier. It is then sent to a stainless steel tubular cracking
furnace where the conditions are maintained at about 480-520°C and 4 atm. The furnace is heated by external flue
gas. The contact surface catalyst within the tubes is pumice or charcoal. The conversion per pass is around 50% and
the ultimate yield is about 95%. The product from the furnace is quenched with cold EDC to prevent the back reaction
and to form condensable product components. Uncondensed gases are sent to a surface heat exchanger to condense
any remaining EDC and VC present in vapor form. The non-condensable HCl is sent to an adjacent process area for
further processing. The condensate is then sent to a VC still or fractionator where VC is taken as an overhead product
and sent to storage after stabilization. The bottoms from the VC fractionator is to an EDC still to further separate EDC
from heavier fractions. Part of the separated EDC is recycled in vapor form and the rest, in liquid form, is used for cold
quench.
In this chapter, equipment typically used in process plants is described. This includes process equipment
such as reactors, towers and exchangers and mechanical equipment such as pumps and compressors.
Process and mechanical equipment used in process plants are discussed in this chapter.
Equipment in process plants can be classified into two categories – process equipment and mechanical equipment.
Process equipment is used in the different processing steps as indicated by the Process Flow Diagram (PFD).
Reactors and heat exchangers are examples of process equipment. Mechanical equipment is used in the transport of
fluids from one process unit to another and also in the compression of gases. Pumps and compressors are examples
of mechanical equipment. Mechanical equipment consists of rotating machinery. Good practices in process plant
layout and piping design requires adequate knowledge of equipment used in process plants and the ability to interpret
equipment documents and drawings. Both these types of equipment are discussed in this chapter.
Towers are tall, slender pieces of vertical equipment found in process plants. The most important example of a tower is
the distillation column, also known as a fractionating tower. The distillation column is used in the separation of
components based on the differences in the boiling points of the components. For example, in the distillation of crude
oil, preheated feed is fed to a “flash zone” in the column where liquid and vapor separate. The lighter fractions boil first
and rise to the top of the column and the heavier fractions remain as liquid and settle at the bottom of the column.
Figure 3.1a shows a PFD for a typical distillation column.
Figure 3.1a
Process Flow Diagram (PFD) for a Typical Distillation Column. (Source: “Process Plant Layout and Piping
Design”, Ed Bausbacher and Roger Hunt, Prentice Hall)
Figure 3.1b shows a typical plan arrangement for a distillation column and Figure 3.1c shows the elevation view of a
distillation column and its ancillary equipment.
Figure 3.1c
Elevation View of a Distillation Column and Ancillary Equipment (Source: “Process Plant Layout and
Piping Design”, Ed Bausbacher and Roger Hunt, Prentice Hall)
A “Process Vessel Sketch” for a typical distillation column. The process vessel sketch gives the major dimensions of
the column including the diameter and tangent-to-tangent height.
Figure 3.2
Process Vessel Sketch for a Distillation Column (Source: “Process Plant Layout and Piping Design”, Ed
Bausbacher and Roger Hunt, Prentice Hall)
An important consideration in piping layout and design is the location of equipment nozzles. Equipment nozzles
provide the connection between equipment and piping. In addition, nozzles are used for instrumentation such as
temperature and pressure sensors. Large diameter nozzles are used in providing maintenance access. The process
vessel sketch also includes information on the location of nozzles. The nozzles are described in a nozzle summary
table, which is shown in Table 3.1. The process vessel sketch and the nozzle summary table provide information for
vessel fabrication.
Table 3.1
Nozzle Summary for a Distillation Column
Symbol Size and Rating Service
A 18” 150# RF Vapor
B 3” 150# RF Reflux
C 6” 150# RF Feed
D 10” 150# RF Reboiler Draw Off
E 10” 150# RF Reboiler Return
F 6” 150# RF Botoms Outlet
Patient 1” 150# RF Pressure
T 1” 150# RF Temperature
L 2” 150# RF Level
Figure 3.3
Nozzle and Platform Elevations for a Distillation Column (Source: “Process Plant Layout and Piping
Design”, Ed Bausbacher and Roger Hunt, Prentice Hall)
Reactors are process units used in accomplishing unit processes. Unit processes are chemical reactions necessary to
transform raw materials to finished products and were discussed in Chapter 2. Reactors are usually vertical, hollow
steel vessels operating at high temperatures and pressures.
Facility for loading and removal of catalysts, mostly in the form of pellets. Very often, reactions take place in the
presence of a ‘catalyst’ material that promotes the reaction but does not take part in the chemical reaction.
Examples of catalysts are alumina, zinc oxide and platinum.
Requirement of space for loading/unloading of catalyst.
Flexibility of connecting lines to accommodate line expansion due to high temperature during operation and
contraction during shut down.
Location of sampling ports to sample catalyst pellets. It is necessary to sample and test the catalyst for its
effectiveness. The catalyst needs to be regenerated periodically after it is “spent”.
Location and sizes of nozzles for catalyst unloading and loading.
The following factors are considered in determining the elevation of the Bottom Tangent Line (BTL) of a reactor:
reactor dimensions, type of heads, type of support and catalyst unloading method. The piping layout for a reactor
should minimize piping runs of expensive alloy piping and should also provide sufficient flexibility for high temperature
piping.
Figure 3.4
Typical Reactor Details (Source: “Process Plant Layout and Piping Design”, Ed Bausbacher and Roger
Hunt, Prentice Hall)
The important nozzles for a reactor are nozzles for raw material inlet and catalyst loading on the top head and nozzles
for product outlet and catalyst unloading on the bottom head. In addition, there are several nozzles for temperature
probes and sampling probes. The layout should leave sufficient room for the withdrawal of the probes. Figure 3.5 is a
process vessel sketch for a reactor showing the location of the important nozzles.
Figure 3.5
Process Vessel Sketch for a Reactor (Source: “Process Plant Layout and Piping Design”, Ed Bausbacher
and Roger Hunt, Prentice Hall)
The different types of supports for a reactor are skirt support, lug support and ring girder support and are shown in
Figure 3.6.
Figure 3.6
Methods for supporting a Reactor (Source: “Process Plant Layout and Piping Design”, Ed Bausbacher
and Roger Hunt, Prentice Hall)
Heat Exchangers are used in heating, cooling, vaporizing, and condensing process fluids by exchanging heat from
other fluids or outside sources.
Types of heat exchangers: The five major types of heat exchangers are Shell and Tube, Double Pipe, Plate and
Frame, Spiral, and Air-cooled and they are illustrated in Figure 3.7.
Figure 3.7
Types of Heat Exchangers (Source: “Process Plant Layout and Piping Design”, Ed Bausbacher and
Roger Hunt, Prentice Hall)
Coolers: A process fluid is cooled using a cooling medium such as cooling water, refrigerant, air or dowtherm.
Heaters: A process fluid is heated using heating media such as hot water, hot oil or condensing steam.
Chiller: A process stream is cooled to very low temperature by using a refrigerant. The refrigerant absorbs heat
from the process stream and evaporates.
Condensers: Process vapors are condensed to liquid state by using cooling water, air or other medium.
Reboilers: Used in distillation systems to boil/vaporize the bottoms liquid using steam/hot oil as the heating
medium.
Heat/Energy conservation: Hot, effluent streams are used in pre-heating feed streams before discharge. This
saves energy and also reduces environmental problems.
A description of the five major types of exchangers is provided in the following section.
1. Shell and Tube Heat Exchanger (STHE): A typical STHE consists of a cylindrical shell containing a bundle of tubes.
Nozzles are provided for the shell side and tube side fluids.
Horizontal baffles are provided to create multiple passes on the tube side.
Vertical baffles in the shell side to ensure a flow pattern that provides good contact between shell and tube side
fluids.
Tubes are supported in a frame called tube sheet.
For horizontal installations, the exchanger is supported by saddles and by lugs for vertical installations.
Layout for STHE: The most important factor is to provide enough space for the removal of tube bundles and for the
removal of shell bonnet.
Figure 3.8 illustrates typical components of a Shell and Tube Heat Exchanger.
Figure 3.8
Shell and tube heat exchanger with floating head (courtesy of the Tubular Exchanger Manufacturers
Association)
2. Plate and frame exchangers: They are generally used in low temperature, low pressure applications. The
advantage they offer is economy of space. Sufficient space must be provided for plate removal and for controls.
3. Spiral heat exchangers: They have the advantages of economy of space and compact layout. Sufficient space
must be provided for opening of swing cover plates and for controls.
4. Double pipe heat exchangers: They are also known as Fin Tube Heat Exchangers. They consist of two concentric
pipes. One of the fluids flows in the inner tube and the other fluid flows in the annular region between the two tubes.
5. Air-Cooled Heat Exchangers: In this type of exchanger, circulating air is the cooling medium. It consists of a bank
of tubes carrying the hot fluid, which is cooled by flow of air across the tube bank. Air fans and their drives occupy
most of the space. Air-cooled exchangers are usually mounted on top of the pipe racks.
Adequate space must be provided for the removal of channel heads, tube bundles and shell covers.
Piping runs should be minimized for expensive, high temperature, alloy piping.
High temperature lines should be routed so as to provide sufficient flexibility for thermal expansion.
Sufficient space must be provided for operator and maintenance access.
Figure 3.9
Typical Layout for Heat Exchangers (Source: “Process Plant Layout and Piping Design”, Ed Bausbacher
and Roger Hunt, Prentice Hall)
Vessels can be grouped into horizontal vessels and vertical vessels. Horizontal vessels are also known as drums or
Mechanical equipment is used in the transport of fluids and also in the compression of gases. Pumps are used in the
transport of fluids and compressors are used in gas compression.
Pumps are mechanical equipment used in the transport of fluids. Pumps add mechanical energy or “head” to the fluid
being transported. The criteria used in the selection of pumps are as follows:
Characteristics and properties of the fluid being pumped including density, viscosity, vapor pressure and chemical
composition.
The capacity or the volume flow rate (gpm or m3/s) of the fluid to be pumped.
The head to be supplied by the pump. This is usually expressed in terms of feet (or meters) of the fluid being
pumped.
Pressure, temperature of the fluid being pumped.
Space constraints.
Cost factors – capital and operating costs.
Maintenance requirements and reliability.
The three major types of pumps are – centrifugal pumps, reciprocating pumps and rotary pumps.
Centrifugal pumps:
Centrifugal pumps are the most commonly used pumps. They are very versatile pumps and can handle a broad range
of flow rates and pressures. They operate at constant speeds. They can be configured either horizontally or vertically
and in single or multiple stages. Figure 3.10 illustrates the typical components of a centrifugal pump, which consists of
an impeller, a casing, and suction and discharge nozzles. Associated with the pump are the motor drive and the base
plate.
Figure 3.10
Typical Components of a Centrifugal Pump (Source: “Process Plant Layout and Piping Design”, Ed
Bausbacher and Roger Hunt, Prentice Hall)
Reciprocating pumps:
Reciprocating pumps consist of a piston-cylinder mechanism. They are typically used in injecting precise amount of
fluids and in handling lower flow rates. Reciprocating pumps are also known as “Positive Displacement Pumps”.
Rotary pumps:
Rotary pumps use gears, screws and cams to move the fluid. They are useful in pumping viscous fluids and in
achieving a constant and smooth discharge.
Net Positive Suction Head (NPSH): The NPSH required (NPSHR) is a measure of the pressure drop from the
inlet nozzle to the eye of the impeller. The pump manufacturer specifies the NPSHR usually in feet of water. The
NPSH available (NPSHA) must be greater than NPSHR. NPSHA is determined by the layout of the source vessel
and the pump.
Allowable Nozzle Loads: Stresses are induced in the suction and discharge nozzles of the pump because of the
forces and displacements of the connecting pipe. These stresses should be within limits specified by the vendor
and by the codes. The limits specified are called as allowable loads.
Vapor Pressure and Cavitation: The vapor pressure of the fluid being pumped is the saturation pressure at the
operating temperature of the pump. This can be obtained from thermodynamic tables and charts. If the pressure in
the pump suction drops below the vapor pressure, the liquid will flash forming some vapor. The liquid–vapor
mixture leads to the formation of vapor bubbles, which collapse upon impact on the surfaces of the impeller and the
casing. This results in the erosion and damage of the impeller and casing surfaces. Cavitation also causes noise,
loss of head and capacity.
Pump piping must be adequately supported so as to avoid excessive loads on pump nozzles.
Pump piping must be routed such that existing support structures can be used.
The length of the suction piping must be minimized to avoid excessive pressure drops.
Pump piping is routed so as to satisfy line flexibility requirements to allow room for line expansion and contraction
39 de 136 30/08/2019 16:12
Practical Process Plant Layout and Piping Design https://www.eit.edu.au/cms/resources/books/practical-process-plant-la...
(thermal effects).
Pumps are located so as to optimize the use of existing structural steel for providing adequate support for pump
piping. It is for this reason that pumps are located adjacent to pipe racks. Pumps can also be located directly under
the process equipment serviced by the pump.
Figure 3.11 is a plan view of typical pump locations and Figure 3.12 is an elevation view of typical pump locations.
Figure 3.11
Plan View of Typical Pump Locations (Source: “Process Plant Layout and Piping Design”, Ed Bausbacher
and Roger Hunt, Prentice Hall)
Figure 3.12
Elevation View of Typical Pump Locations (Source: “Process Plant Layout and Piping Design”, Ed
Bausbacher and Roger Hunt, Prentice Hall)
Figure 3.13
Typical Components of Suction and Discharge Piping (Source: “Process Plant Layout and Piping Design”,
Ed Bausbacher and Roger Hunt, Prentice Hall)
Process and mechanical equipment typically found in process plants have been discussed in this chapter. The different
types of equipment, their typical applications and the factors to be considered in the design and layout of such
equipment have been explained. The equipment considered in this chapter includes towers, reactors, heat exchangers
and pumps. The nozzle specifications and supports for equipment have also been briefly discussed.
This chapter discusses the basic principles used in plant layout. Plant layout specifications and guidelines
are described. The starting point for the design of process plants and piping system is the generation of “Plot
Plans” and equipment arrangement drawings. Examples of plot plans and equipment arrangement drawings
are provided in this chapter.
Plant layout specifications provide guidelines and requirements for arrangement of equipment and structures within a
plant. These guidelines take into account compliance with national and local codes and regulations. Additional factors
to be considered are:
Plant safety
Plant operability
Plant maintenance
Site conditions – soil, seismic data etc.
Environment
Atmospheric conditions – prevailing winds, average ambient temperature
The following terminology is frequently used in plant layout and plot plans:
Operator Access: This is the space required between units for operator functions such as walking, climbing,
operating valves, viewing instruments and for safe exit in case of an emergency.
Maintenance access: This is the space required for servicing of process equipment and for removal and
restoration of components of equipment.
Plot plans are plan view drawings of the processing facility. Plot plans specify the location of all equipment and
associated structures (pipe racks, buildings) in the facility. Plot plans play a crucial in determining the real estate and
space requirements for the plant and hence the cost of the plant. Plot plans are generated during the preliminary
design phase but are constantly reviewed and updated as the project progresses. Plot plans are used in every phase
of the project and they are used by every project discipline. The use of plot plans by different disciplines is described
here.
The development of plot plans is not an exact science. It varies with the unique requirements of each process plant.
The layout designer must anticipate field problems during construction, operation and maintenance. The goal is to
produce a safe, cost-effective plant with ease of operation and maintenance.
As the project progresses, the following plot plans are produced in sequence.
Proposal Plot Plan: This is developed during the estimate phase of the project. It includes only principal
equipment, main supporting facilities and overall dimensions. It is used in the estimation of bulk materials and
presented to the client for approval of the overall arrangement concept.
Planning Plot Plan: This is produced after the award of the contract award. The proposal plot plan is reviewed,
updated and approved by client. The planning plot plan serves as a working document for the plant layout phase of
the project. In the planning plot plan, different areas of the plant are identified and equipment is tagged and
positioned at appropriate locations.
Construction Plot Plan: This is produced as a result of the activities in the plant layout phase of the project. At
this stage, all equipment has been sized and positioned. Equipment positions are indicated in terms of coordinate
dimensions (North-South, East-West, and Elevations). Additionally, the location of pipe racks, support structures
and ancillaries has also been finalized. Locations of access roads, paths and buildings have also been finalized.
This is the final plot plan and is used in the construction of the plant.
Figure 4.1
Sample construction plot plan (Source: “Process Plant Layout and Piping Design”, Ed Bausbacher and
Roger Hunt, Prentice Hall).
Equipment Lists: Major equipment includes reactors, towers, furnaces, exchangers, pumps, compressors, drums
and miscellaneous (lube oil console, corrosion inhibitor packages etc.)
Process Flow Diagram: Discussed in detail in Module 2.
Grade Mounted Arrangement: This is also known as “Horizontal In-Line Arrangement”. In this arrangement,
equipment is located in a rectangular area mostly at grade level and serviced by access roads and pipe racks. The
advantages are it is easy to construct and it is easy to access for operation and maintenance. The disadvantages
are large real estate required and longer run of piping and cables. This type of arrangement is mostly used in
refineries and in chemical/petrochemical plants.
Figure 4.2
Grade Mounted Arrangement (Source: Process Plant Layout and Piping Disign, Ed Bausbacher and
Roger Hunt)
Advantages:
Small amount of space required, compact plants, protection from extreme weather conditions, accommodation of
gravity feeds, smaller runs of piping and cables.
Disadvantages:
Construction is more complex, access for operation and maintenance is cumbersome, pumping costs can increase.
Figure 4.3
Structure Mounted Arrangement (Source: Process Plant Layout and Piping Design, Ed Bausbaucher and
Roger Hunt)
Figure 4.4
Typical Pipe Rack Configuration (Source: Process Plant Layout and Piping Design, Ed Bausbacher and
Roger Hunt, Prentice Hall)
Figure 4.5
Equipment Arrangement Plan (Source: “Pipe Drafting and Design”, Roy Parisher and Robert Rhea, Gulf
Publishing)
Plant Layout is a very important preliminary activity in the design of process plants and piping systems. Plot plans are
documents generated during the plant layout phase. The guidelines and procedures commonly used in the
development of plot plans have been described in this chapter.
1. Using the PFD and the process description for the production of vinyl chloride (which were given in Practical
2. Compare and discuss the plot plan that you have developed with those by your peers in the class. Observe the
difference and the good features in different plot plans for the same facility.
EDC vapor at a pressure of 4 atm. is dried by using a silica gel drier. It is then sent to a stainless steel tubular cracking
furnace where the conditions are maintained at about 480-520°C and 4 atm. The furnace is heated by external flue
gas. The contact surface catalyst within the tubes is pumice or charcoal. The conversion per pass is around 50% and
the ultimate yield is about 95%. The product from the furnace is quenched with cold EDC to prevent the back reaction
and to form condensable product components. Uncondensed gases are sent to a surface heat exchanger to condense
any remaining EDC and VC present in vapor form. The non-condensable HCl is sent to an adjacent process area for
further processing. The condensate is then sent to a VC still or fractionator where VC is taken as an overhead product
and sent to storage after stabilization. The bottoms from the VC fractionator is to an EDC still to further separate EDC
from heavier fractions. Part of the separated EDC is recycled in vapor form and the rest, in liquid form, is used for cold
quench.
This chapter covers the fundamentals of Piping and Instrumentation Diagrams (P&IDs) and their significance
in process plant layout and piping design. The symbols and terminologies used in P&IDs are described.
Control valve manifolds and meter runs are also discussed in this chapter.
Piping and Instrumentation Diagrams (P&IDs) play a crucial role in the design and engineering of process plants and
piping systems. P&IDs are also known as “Engineering Flow Diagrams” or “Mechanical Flow Diagrams”. P&IDs are
schematic diagrams that contain engineering and design details of the process plants. Thus, the P&IDs are much more
detailed than PFDs. A P&ID is a working document that is used by every discipline involved in the design, engineering
and construction of process plants. It is used as a reference for checking engineering and design documents and
drawings associated with a project. P&IDs are also used in material take-off, that is, in generating a “Bill of Materials”
for procurement and construction. P&IDs typically contain the following information:
All the equipment and their specifications, usually presented in the form of a table.
All piping and line specifications.
All piping system components such as fittings, flanges and valves with their specifications.
All instrumentation and control components.
Flow directions.
Information on process variables such as pressure and temperature.
Material Specifications.
Specialty Items such as strainers.
The primary functions of instrument and control components are monitoring, display, recording and control of process
variables. Instrument and control symbols consist of an instrument bubble with the instrument abbreviation lettered
inside the bubble. The abbreviation completely describes the function of the instrument/control component.
Instruments/control elements can be grouped into different categories based on the process variable that the
instrument or the control element is monitoring or controlling. The first letter in the instrument abbreviation indicates the
process variable being monitored or controlled. The process variables are:
Flow (F)
Instruments can be further grouped into different categories based the function they perform. The second letter in the
instrument abbreviation indicates the instrument function. The common functions performed by instrument and control
components are:
Alarms (A): Alarms are devices responsible for alerting plant operators about an upset condition of the process
variable. Alarms typically consist of sound and light outputs that attract the attention of the plant operators.
Controllers (C): Controllers are responsible for the control of the process variable. A typical controller receives input
on the status of the process variable and compares the value with the “set point” and initiates the appropriate
action. Actuators and control valves execute the control action.
Indicator (I): An indicator is a device that indicates the value of the process variable. Typically, indicators are digital
or analog devices located in a remote control building. Display devices are also located at the process unit for local
access and back up purposes. Indicators located at the process unit are also known as “Gauges”. A Level Gauge
(LG) is an indicator used in the measurement of liquid level in process vessels.
Sensors: Sensors are devices that actually measure the value of the process variable. Examples of sensors are
thermocouples and orifice meters used in temperature and flow measurements respectively. Transducers are used
in converting the analog measurements into digital values.
Recorders (R): Recorders are devices that record the value of the process variable in the form of time dependent
graph or strip chart. This information is very useful in monitoring plant performance and in quality control of the
products.
Transmitters (T): Transmitters are devices that transmit the information on the process variable to controllers or to
remotely located indicators.
Typically instrument abbreviations consist of two letters; the first indicating the process variable and the second
indicating the instrument/controller function. As an example, the instrument abbreviation “TI” denotes a “Temperature
Indicator”. Occasionally, third letter is included in the instrument abbreviation to describe a simultaneous function or a
special function. The following examples illustrate this situation: the abbreviation “FRC” denotes a “Flow Recording
Controller” which describes both the recording and control functions and the abbreviation “LAL” denotes a “Level Alarm
Low” which describes an alarm used in the event of a low level upset condition.
The following list contains some of the instrument abbreviations and their expansions.
Figure 5.1
Typical instrument symbols used in P&IDs.
Figure 5.2 represents a P&ID typically used in the design and engineering of process plants. The level of detail in this
diagram is quite obvious and the P&ID contains design and engineering information that is used by different disciplines
involved in the project. The following observations can be made about the P&ID shown in Figure 5.2.
The three major equipments are: V – 230A Third Stage Suction Scrubber, C – 235 Third Stage Compressor, E –
236A Third Stage Discharge Cooler. The equipment table on the P&ID gives the details for each of this equipment.
This includes the equipment dimensions, design pressure and temperature, and material of construction.
Information on all the lines is given. Each line is labeled with the line specification. For example, the line leaving the
compressor is labeled 6” – PG – 117 – GE – 2. The nominal pipe size is 6”; PG is the service abbreviation and
denotes “Process Gas”. 117 is the line sequence number. GE – 2 is the piping material specification. Information on
all the valves and valve specifications can also be seen on the P&ID.
Information on all the instrumentation is also presented. For example, the instrument PI / C235A-1 is the Pressure
Indicator for C – 235A and is a board mounted instrument in the control room.
Figure 5.3
Sample Piping and Instrumentation Diagram (P&ID)
The function of a control valve is to control the flow rate of a fluid through a piping system. In addition to an automatic
Figure 5.4
Typical Control Valve Manifold Arrangement
The main component in the system is the control valve, FRC 201, which is typically a globe valve with a hydraulic or
pneumatic actuator that automatically controls the flow. Valves are discussed in greater detail in Chapter 8. On either
side of the control valve are reducers. The reducers connect to a pair of block valves. When the block valves are open,
the flow occurs through the control valve. When the block valves are closed, the flow occurs through the bypass valve
shown on top of the control valve. The bypass valve is used in manually controlling the flow when the control valve is
Sufficient space must be provided for hand wheels. The hand wheels must be oriented away from piping,
equipment, access ways, and other structures.
Adequate spacing for locating the actuator on top of the control valve must be provided.
The components of a control valve manifold have significant weight and must be adequately supported with
suitable pipe supports.
An orifice meter is typically used in measuring the flow rates of fluids. The orifice meter consists of an orifice plate and
an orifice flange assembly as shown in Figure 5.4.
Figure 5.5
Typical Orifice Flange Assembly
Figure 5.6
Orifice Plate
The orifice flanges have valve taps that are connected to pressure sensing instruments to measure the pressure
difference. The pressure difference correlates with the flow rate. The following factors must be considered while
designing a layout for orifice meters.
The flow pattern through the orifice must be smooth with minimal turbulence. Turbulence is usually created by the
presence of obstructions such as fittings and valves. Having sufficient length of straight pipe upstream and
downstream of the orifice ensures a smooth flow pattern near the orifice. These lengths of straight pipe are known
as “meter runs”.
Piping layout for flow meters must include meter runs of at least 30 pipe diameters upstream of the orifice and 6
pipe diameters downstream of the orifice.
Piping and Instrumentation Diagrams (P&IDs) are important working documents used in the design and construction of
process plants. Symbols and terminologies used in P&IDs have been explained in this chapter. The concepts required
for understanding and using P&IDs have been explained. The points to be considered during the layout and design of
control valve manifolds and flow meters have also been explained in this chapter.
a. PSV: _____________________________________
b. FRC: _____________________________________
c. TI: _______________________________________
d. LAL: _____________________________________
e. HCV: _____________________________________
7. On a P&ID, the equipment table for a compressor includes the following entry:
Press. Suct. / Disch. 285 psig / 926 psig
Explain clearly the meaning of this entry.
This chapter describes the documentation used in the design, procurement and construction of process
plants and piping systems. Examples of documents used include Line Lists and Piping Specifications. This
chapter also discusses the tools used in the design of process plants such as piping isometrics and 3D
models.
Proper and accurate documentation is essential for the design and construction of process plants in a timely and cost-
effective manner. Process plants and associated piping systems involve equipment, piping, fittings and instruments,
which need to be accurately specified for procurement purposes. These specifications involve extensive amounts of
dimensional, material and other data. The integrity of this data must be maintained through the different phases of the
project needs to be accurate at the time of procurement of materials. The data is represented in different documents
such as P&IDs, Equipment Lists, Line Lists, Valve Lists and Instrument Lists. Inappropriate and inconsistent
documentation and data can lead to costly project delays, field re-work and even difficulties during plant operation and
maintenance. Personnel involved in plant layout and piping design should be able understand and interpret these
The equipment required for processing is obtained from the Process Flow Diagram (PFD, discussed in Chapter 2).
With additional input, the precise location of equipment is determined and represented in the form of an “Equipment
Arrangement Diagram”. The equipment arrangement drawing is a plan view of equipment locations. Figure 6.1 is an
equipment arrangement drawing for a deck of an offshore platform. The location coordinates are provided in the
“Equipment List” (discussed in the next section).
Figure 6.1
Equipment Arrangement Drawing
Table 6.1 is the equipment list for the deck shown in Figure 6.1. The equipment list consists of the equipment tag and
equipment description. The equipment location is provided by means of the coordinates in terms of North, East and
Elevation. The coordinates in Table 6.1 are given in millimeters (mm). The equipment arrangement drawing and the
equipment list should be used in conjunction with each other. It is quite common to place the equipment list on the
equipment arrangement drawing.
Table 6.1
Equipment List
Tag Description North East Elev.
FA-3101A Backup 1st/2nd Stage Compressor 487200 435248 45000
FA-3102A 2nd Stage Production Separator 480550 432200 45000
FA-3102B 2nd Stage Production Separator 474600 432200 45000
PA-3901A Stand-by Generator Package 439447 433725 40513
PA-3902A Main Power Generator Package 462554 432063 40665
PA-3902B Main Power Generator Package 457054 432063 40665
PA-3902C Main Power Generator Package 451554 432063 40665
PA-3902D Main Power Generator Package 446054 432063 40665
SK-3451A1 TEG Regenerator Skid 495200 423588 40513
SK-3451B1 TEG Regenerator Skid 495200 437610 40513
R-1 Generator Building 437996 428631 40513
Piping and Instrumentation Diagrams (P&IDs) are very important working documents in the design and engineering of
process plants and piping systems. P&IDs have been discussed in detail in Chapter 5. The engineering details and
specifications of all piping and associated components are represented on the P&ID. P&IDs are used in generating
Piping Line Lists and also in material take-offs for valves and specialty items. Figure 5.2 represents a sample P&ID.
Piping Line Lists are tables containing data associated with each pipe segment. In this sense, Piping Line Lists are
databases that contain all information associated with a pipe segment.
Each pipe segment is assigned a unique “Line Identification Number”, also known as “Line Number”. The pipe
segments are referenced using this line number. The line number consists of information on the line size, the fluid
being serviced and the piping specification. The contents of a piping line number are explained using the following
example: 10” – P – C – 0006 – EA21. In the preceding example:
Typical data associated with a pipe segment can be classified into “Process Data” and “Mechanical Data”. There are
many items that are common for process data as well as mechanical data.
Process data is data related to the process aspects of the line segment and includes the following items.
Line Number.
Service (From Unit X To Unit Y, that is From Origin To Destination.).
P&ID Number, which is the drawing number of the P&ID in which the pipe segment is located.
Operating Pressure.
Operating Temperature.
Design Pressure.
Design Temperature.
Phase (Liquid, Vapor or a 2-phase mixture).
Flow Rate (lbs/hr, kg/s, gpm, SCFM, SCMS).
Molecular Weight.
Density (lbm/ft3, kg/m3).
Viscosity (cP, lbf-sec/ft2, N.
s/m2)
Velocity (ft/sec, m/s).
Equivalent Length (ft, m).
Pressure Drop (psi, kPa).
Process Remarks.
Revision.
Mechanical data is data related to the mechanical aspects of the line segment and includes the following items.
Line Number.
Service (From Unit X To Unit Y, that is From Origin To Destination.).
P&ID Number, that is, the drawing number of the P&ID in which the pipe segment is located.
Pipe Material.
Operating Pressure.
Operating Temperature.
Design Pressure.
Design Temperature.
Insulation (Thickness, Purpose, Specification, Trace Type).
Painting Code.
Pressure Testing (method and test pressure used).
Stress Relief.
Cleaning Specifications.
Mechanical Remarks.
Piping codes are a broad set of guidelines for the design and engineering of piping facilities. The main objective of
codes is to ensure the use of safe design practices and consequently the safe operation and maintenance of such
facilities. Codes are developed by committees, which have a broad range of experience and expertise. Codes are
influenced by government regulations for operator and worker safety in process plants. They are also constantly
updated using feedback from various sources. The codes that govern design of piping systems are known as “B31
Code for Pressure Piping” and have been developed by the American Society of Mechanical Engineers (ASME).
ASME B31 was earlier known as ANSI B31. ANSI represents American National Standards Institute. The different
ASME B31 codes are listed here.
Among the codes listed here, the code that is most relevant to the design of process plants is ASME B31.3. A
summary of ASME B31.3 Process Piping code is provided here.
ASME B31.3 Process Piping Code: Used in the design of chemical and petroleum plants and refineries processing
chemicals and hydrocarbons, water and steam.
This code prescribes requirements for materials and components, design, fabrication, assembly, erection, examination,
inspection and testing of piping. This code applies to piping for all fluids including: (1) raw, intermediate, and finished
chemicals; (2) petroleum products; (3) gas, steam, air and water; (4) fluidized solids; (5) refrigerants; and (6) cryogenic
fluids. Also included is piping which interconnects pieces or stages within a packaged equipment assembly.
Piping Specifications, also known as “pipe specs” are detailed guidelines for the design, fabrication and construction of
the components of piping systems. Pipe specs are relevant to a particular project and are written to maintain uniformity
and consistency through the different phases of the project. Pipe specs are also known as “Piping Specification
Classes”. The fluid flowing in the pipe, the material properties, the design temperature and the design pressure are
considered in developing specification classes.
Figure 6.2
Sample Piping Specification
Pipe specs use service conditions to establish many parameters as is evident from the sample shown in Figure 6.2.
Piping engineers and designers use pipe specs to establish sizes, pound ratings, and dimensions of pipe, fittings,
valves and associated equipment. Pipe specs are also used in pipe stress analysis to ensure that the stresses in the
pipe material are within the limits specified by the code. The procurement department uses pipe specs to ensure the
purchase of appropriate pipe, fittings, valves and other components of piping systems. Welders and fabricators use
pipe specs to ensure the use of proper materials and joining methods.
Piping isometrics are pictorial representations of piping systems. They help in the visualization of piping systems and
are used in the design, procurement, fabrication and construction phases of the project. The pictorial representation is
obtained by drawing along the isometric axes. One of the isometric axes is vertical while the other two are at an angle
of 30° to the horizontal axis.
Figure 6.3 depicts the translation of a regular orthographic representation of a piping system into a piping isometric
drawing. The most important step in generating a piping isometric drawing is to establish the North direction along one
of the isometric axes. Consequently, the other directions are automatically established as shown in Figure 6.3. The
point at which the pipe changes direction is called as “Turning Point (TP)”. The turning point signifies the use of elbows
to effect the change in direction. Several turning points can be observed in Figure 6.3. Piping isometrics are also
commonly known as “piping isos” or simply as “isos”. Isos are schematic single line drawings and are not drawn to
scale. However, they are dimensioned and are drawn by maintaining proper proportions. The details of the
components of the piping system such as materials and pound ratings are given by using callouts or notes.
Figure 6.4 shows how a piping iso is generated for one of the lines (with line specification 01 – 2 – C30 – 10”), which
connects nozzle N1 from vessel V – 101 with nozzle C of exchanger E – 101.
One of the most important uses of isos is to generate the “Bill of Materials (BOM)” for each line in the process plant.
The BOM is generated by using a process known as “material take-off”. Using this process, all the components of a
line are tabulated for purchase or procurement. The typical components of a line include the following items.
Straight Pipe
Elbows
Flanges
Tees
Valves
Instrument Items
Gaskets
Nuts
Bolts
Specialty Items
Properly dimensioned isos along with the BOM are provided to the fabricators who build the components of the line.
Further, the isos serve as an aid to the construction and erection of the facility by providing construction personnel
information on pipe routing and the locations of tie-ins and connections.
The advances in computer technology and the availability of modeling software has made 3D modeling of piping
systems an integral part of the design and engineering of process plants. The features and advantages 3D models of
piping systems are listed here.
3D models are real-size representations of the processing facility including equipment, pipe, fittings, valves,
instruments, support structures and foundations. Every single detail of the facility is captured in the 3D model.
The engineering data associated with each component is also integrated into the model. This data forms the
“engineering database” for the project and is updated as needed as the project progresses through different
phases.
3D models are great visualization tools for designers, engineers and construction personnel.
Most 3D modeling software are capable of performing “interference checking” and produce “clash reports” that alert
designers about potential clashes between components of the process plants. The components can be relocated
during the design phase thus saving expensive field rework and avoiding project delays.
3D models can be imported into animation software to create “walkthroughs”. Client walkthroughs are very useful
in expediting the project and in improving the communication between the client and the engineering and design
personnel.
3D models and animations are also used in producing training videos for the safe operation and maintenance of
the plant.
Figure 6.6
3D Model of a Processing Facility Generated Using Intergraph PDS Software (Source:
ppm.Intergraph.com).
Figure 6.7
3D Model of a Floating Production Storage and Off-loading (FPSO) Facility Generated Using Intergraph
PDS Software (Source: ppm.Intergraph.com).
Design and engineering of piping facilities generates plenty of documents, which play a crucial role of representing the
details of the facility and also in communication between engineers and designers from different disciplines. This
chapter provides a working knowledge of documents such as equipment lists and piping line lists. Tools such as piping
isometric drawings and 3D models also play a very important role in the design, engineering, procurement and
construction of process plants. A basic understanding of these tools is provided in this chapter.
Generate a partial piping line list from the P & ID shown in Figure 5.2
Piping Materials: Steel - Carbon Steel and Alloy Steels (SS), Cast Iron, Copper, Concrete, Brass, Aluminum,
Composite (FRP).
Piping Materials are described by “Piping Specifications” – a document that describes the material composition and
processing methods (discussed in Chapter 6)
The material to be used is dictated by service conditions, namely, fluid being transported, temperature and pressure
Pipe Manufacturing Methods: Seamless Pipe, Butt Welded Pipe, Spiral Welded pipe.
Pipe Size and Dimensions: OD/ID, Nominal Pipe Size (NPS)
Wall thickness (weight): Standard (S), Extra strong (X), Double Extra strong (XX)
Also described in terms of pipe schedules. Schedule 40, 80, 120 etc.
For NPS 1/8” to 12” NPS, OD > NPS
For NPS 14” and above, OD = NPS
Commercial steel pipe data (Given in Appendix)
Methods of joining pipe: Butt-Welded (BW), Screwed (SCRD) or Threaded (THRD) and Socket-Weld (SW).
Figure 7.1
Pipe Joining Methods
Table 7.1
American Standard and API Thread Engagement
(Source: Pipe Drafting and Design, Roy Parisher and Robert Rhea)
1. The material to be used for piping is based on the following parameters: _____________, ______________and
_______________________.
These parameters are collectively referred to as _________________________.
2. The classification of pipe into Standard (S), Extra Strong (x) and Double Extra Strong (xx) is based on
__________________________.
3. A pipe has an OD of 10.75 in and its wall thickness is 0.365 in. The ID of the pipe is ___________.
5. The surface area of the pipe in question 3 per foot length is _________ ft2.
6. Based on the results of question 5, the insulation surface area required for 150 ft of pipe is ___________ft2.
7. The volume of the pipe material is the metal area x length of pipe. The weight of pipe is volume of pipe material x
specific weight of pipe material. The specific weight of commercial steel is
490 lb / ft3. (Show your calculations for this problem)
a. Calculate the weight of 6 in nominal steel pipe per foot length. The pipe ID is 5.761 in and the pipe OD is 6.625 in.
b. A section of an offshore platform uses 650 ft of this pipe. What is the total weight of the pipe?
Note 1: The letters s,x, and xx in the column of Schedule Note 2: The values shown in square feet for the
Numbers indicate Standard, Extra Strong, and Double Extra Transverse Internal Area also represent the volume in
Strong Pipe, respectively. cubic feet per foot of pipe length.
Courtesy of Crane Co.
1. The material to be used for piping is based on the following parameters: _____________, ______________and
_______________________.
78 de 136 30/08/2019 16:12
Practical Process Plant Layout and Piping Design https://www.eit.edu.au/cms/resources/books/practical-process-plant-la...
These parameters are collectively referred to as _________________________.
2. The classification of pipe into Standard (S), Extra Strong (x) and Double Extra Strong (xx) is based on
__________________________.
3. A pipe has an OD of 273.1mm and its wall thickness is 9.271mm. The ID of the pipe is ___________.
5. The surface area of the pipe in question 3 per metre length is _________ m2.
6. Based on the results of question 5, the insulation surface area required for 50 ft of pipe is ___________m2.
7. The volume of the pipe material is the metal area x length of pipe. The weight of pipe is volume of pipe material x
specific weight of pipe material. The specific weight of commercial steel is
7850kg/m. (Show your calculations for this problem)
a. Calculate the weight of DN 15.mm nominal steel pipe per metre length. The pipe ID is 146.3mm and the pipe OD is
168.3mm
b. A section of an offshore platform uses 200m of this pipe. What is the total weight of the pipe?
This chapter describes fittings, flanges and valves. It describes their different types and sizes of fittings. It
also describes flange types, ratings and different facings. Types of valves, their parts and valve operators are
also described.
The elements of a piping system used in connecting and capping pipes are described here. Fittings accomplish
change in pipe direction, create branch lines and facilitate change in pipe size.
Figure 8.1 illustrates the applications of fittings. Fitting connections could be:
BW (NPS > 3.0 in)
SW or SCRD (NPS ≤ 3.0 in)
Figure 8.1
Pipe Fittings
Figure 8.2
Welding Clearances for Stub-in fittings (Source: “Pipe Drafting and Design”, Roy Parisher and Robert
Rhea, 2nd Edition, Gulf Publishing.)
Elbows: Also known as “ell”. They facilitate change in pipe direction. Most commonly used elbows are 90° and 45°
elbows. Based on the turn radius, ells are classified as Long Radius (LR) and Short Radius (SR). For welded
fittings and LR ell, the center to end distance is (1.5)(NPS) and for SR ell, it is (1.0)(NPS). (Refer to Appendix 3 for
dimensions). Unless otherwise specified, LR ell is assumed. In AC ductwork, “mitered elbows” are used.
80 de 136 30/08/2019 16:12
Practical Process Plant Layout and Piping Design https://www.eit.edu.au/cms/resources/books/practical-process-plant-la...
Tees: Tees are used in providing branch connections. Tees are of two types - “straight tee” and “reducing tee”. The
main pipe off which the branches are created is known as the “header”.
Stub-ins: Here, holes are cut into the header and branch pipes are welded on. Reinforcing pads are used to
strengthen the area around the hole. igure 8.2 illustrates welding clearances required for stub-ins.
Reducers: Reducers are used in connecting pipes of different sizes. The two types of reducers are “concentric” and
“eccentric”. In concentric reducers, the pipe center lines up while in eccentric reducers there is an “offset” in pipe
center lines and it is equal to one half the difference between the diameters. The configurations for eccentric
reducers are “Flat On Bottom (FOB)” and “Flat On Top (FOT)”. The FOB configuration can be supported on a pipe
rack.
Weld Cap: Used in sealing an open end of pipe.
Pipe Nipples: Small lengths (usually 3 in) of pipe used between SCRD and SW fittings.
Screwed (Threaded) and Socket Weld (SW) Fittings: Normally used for pipes with NPS 3 in and smaller. Forged
Steel (FS) threaded and socket weld fittings are available in pressure classes of 3000 lbs and 6000 lbs.
Table 8.1 provides the dimensions for threaded and socket weld fittings.
Table 8.1
Dimensions for Socket Weld and Thread Fittings
Note: When fittings are welded to each other, it is termed as “Fitting Make-up”. Fitting make-up dimensioning exercises
are given in Practical Exercises (PE) 8A and 8B and 8C. All fitting dimensions are given in Appendix 3.
Abbreviations:
BBE: Beveled Both Ends
TBE: Threaded Both Ends
PBE: Plain Both Ends
BLE / TSE: Beveled Large End / Threaded Small End
Facing Page
Fitting Dimensions Chart (Source: Courtesy of Taylor Forge)
82 de 136 30/08/2019 16:12
Practical Process Plant Layout and Piping Design https://www.eit.edu.au/cms/resources/books/practical-process-plant-la...
Flanges are devices used in connecting pipes to equipment nozzles (Figures 8.3 and 8.4) and to devices such as
valves. Flanged connections are an effective alternative to welded or threaded connections and provide an advantage
of easy dismantling for maintenance and inspection.
Figure 8.3
Flange connecting pipe to a vessel nozzle
Figure 8.4
Reducing flange connecting pipe to vessel nozzle
Flange Ratings: Flanges are often identified by their ratings as in “150 pound flange” also represented as 150 # or 150
lb. Flange ratings are also known as “pressure ratings” and represent the maximum pressure allowed by the codes at
a given temperature. Forged Steel (FS) flanges are available in the following ratings: 150 #, 300 #, 400 #, 600 #, 900
#, 1500 #, and 2500 #. A flange rating of 150 # means that it can be used up to a maximum pressure of 150 psig at a
system temperature of 500°F. If the temperature increases to 750°F, the next higher rated flange (300 #) should be
used. At a system temperature of 750°F, the maximum pressure allowed is 100 psig and therefore a 150 # flange will
87 de 136 30/08/2019 16:12
Practical Process Plant Layout and Piping Design https://www.eit.edu.au/cms/resources/books/practical-process-plant-la...
not suffice. Both the flange diameter and thickness increase with pressure ratings.
Flange dimensions are given in Appendices 4, 5, 6 and 7 for different ratings and different types of flanges.
Flange Facings:
Flat Face (FF): The mating surfaces are flat. (Figure 8.5)
Raised Face (RF): The mating surfaces have a raised face of 1/16” for 150 # and 300 # flanges and 1/4” for higher
ratings. In the flange dimensions charts, the 1/4” raised face is nor included and must be added. However, the
1/16” dimension is included. (Figure 8.6)
Ring Type Joint (RTJ): The mating surfaces have a groove which houses a metallic ring that provides the sealing
mechanism when tightened. No gaskets are used. (Figure 8.7)
Figure 8.5
Flat Face Weld Neck Flange
Figure 8.6
Raised Face Weld Neck Flange
Figure 8.7
Ring Type Joint Weld Neck Flange
Types of Flanges:
Flange Accessories:
Bolts
Gaskets
Abbreviations:
RFWN – Raised Face Weld Neck Flange.
Flange dimensioning problems are given in Practical Exercise 8D.
A valve is a device that controls and regulates the flow of fluids. The different functions that can be performed by a
valve are:
Body
Regulator or valve element
Valve Seat
Hand wheel
Stem
Gate Valve: Consists of a gate as the regulator. Used primarily for on/off applications, that is fully open or fully
closed.
Globe Valve: Consists of a globe as the valve element. Used in throttling (gradually increasing or decreasing the
flow) applications. Flow resistance and pressure drop are substantially higher than gate valves. Flow resistance
coefficients are given in Table 8.2.
Angle Valve: Used in throttling and in changing flow direction.
Check Valve: Used in preventing back flow or flow in the reverse direction. Usually used in conjunction with gate or
globe valves. The types are “Swing Check Valve” and “Lift Check Valve”.
Ball Valves: Uses a hollow metal ball as the regulator. Provides tight closure and simple open/close operation.
Plug Valve: Uses a hollow, tapered wedge as the valve element. Provides a tight closure but requires constant
lubrication.
Butterfly Valve: Has a very simple valve body (a ring), which houses a wafer as the valve element. Has lower
turbulence and pressure drop and is useful for larger flow rates.
Relief Valves: Pressure Safety Valve (PSV) is used in maintaining system pressure at safe levels. PSV opens when
the system pressure exceeds safety limits and closes when the system returns to normal level.
Control Valves: Usually automated globe valves used in monitoring and regulating process variables. Control Valve
Manifolds are described in Chapter 5.
Valve Operators: Devices used in opening and closing valves. There are two types of operators – manual and
automatic.
(a)
(b)
Figure 8.8 a & b
Types of Valves (Source: “Flow of Fluids”, Crane Technical Paper no. 410)
Table 8.2
Friction Loss Coefficients for Fittings and Valves Source: “Chemical Engineers’ Handbook”, Perry,
5th edition, McGraw-Hill.
The different components of a piping system viz., fittings, flanges and Valves have been described in this chapter.
Different types of fittings and pipe measures have been mentioned. Flange types, ratings and facings are listed here.
Figure 9.1
Piping arrangement drawing- single line
Figure 9.2
“Section A-A” Elevation view
Figure 9.3
3-D model of Unit 01
Figure 9.4
Line 01-12-C30-4 (Plans, Sections and Isometric)
Figure 9.5
Model of a piping assembly mounted on a skid. (Model courtesy of Gene Eckert, ECAD, Inc.)
Figure 9.8
Piping drawing used in fabrication and construction.
This chapter provides an overview of materials commonly used in piping systems. It describes classification
and specification of materials. It also describes factors used in selection of materials.
Introduction.
Material classification systems and specifications.
Common ASTM piping materials.
Selection criteria for materials.
Piping specifications (piping classes).
Material testing and certificates.
Generic descriptions
Trade names
Standardized alphanumeric designations
Generic descriptions: Generic descriptions group materials into broad categories based on composition and
properties. Generic descriptions can range from broad descriptions to specific, detailed descriptions. Examples of
generic descriptions are:
Trade Names: Manufactures use trade names to provide unique identification to their products. Examples of trade
names are:
Inconel 625
Incoloy 825
Hastelloy C-276
Carlson Alloy 2205 Duplex SS
Allegheny Ludlum AL 2205 Duplex SS
UR52+ Duplex SS
Alphanumeric Description: Alphanumeric descriptions for materials originate from professional and standards
organizations such as American Society for Testing of Materials (ASTM) and American Iron and Steel Institute (AISI).
The overwhelming number of such descriptions has created a need for a common, widely accepted and used
numbering system. The result has been the emergence of Unified Numbering System (UNS). However, the reality is
that the use of prevailing designations from ASTM, AISI will continue despite the presence of UNS descriptors.
The alphanumeric designations of AISI and UNS are briefly described here.
AISI Numbering System: The AISI designation for carbon steels and low alloy steels consists of a four-digit number.
The first and the second digits indicate the primary and secondary alloy classes to which the steel belongs. The third
and fourth digits, xx, indicate the carbon content in 0.xx %. Examples of AISI material designations are:
Unified Numbering System (UNS): The Unified Numbering System avoids the confusion of multiple designations
(from different organizations) for the same material by providing a unique and consistent identification number. UNS is
not a specification; it does not specify requirements of quality, composition and mechanical properties. It provides the
uniformity required for efficient indexing, record keeping and cross-referencing. The use of UNS is rapidly increasing
and many codes such as B31.3 are beginning to use UNS designations.
The UNS designation has six alphanumeric characters – a letter prefix followed by five digits. Usually, the letter prefix
indicates the family of metals (A for aluminum, S for Stainless Steels). Group examples of UNS designations are
described here.
G00001 – G99999: AISI and SAE (Society of Automotive Engineers) carbon and alloy steels
S00001 – S99999: Heat and corrosion resistant stainless steels.
A 00001 – A99999: Aluminum and aluminum alloys
C00001 – C99999: Copper and copper alloys.
Designations and Descriptions of Common Piping Materials: Most components of piping systems are constructed
from carbon steels and alloy steels such as stainless steels. Common ASTM designations and descriptions of pipe
materials are given here.
ASTM A106 Gr.B: Carbon steel seamless pipe (most commonly used material for pipe)
ASTM A53 Gr.B: Carbon steel seamless or Electric Resistance Welded (ERW) pipe.
ASTM A333 Gr.6: Low and Intermediate Alloy Steel pipe
ASTM A312 TP304: Seamless Stainless Steel pipe.
ASTM B42: Copper alloy pipe
ASTM B161: Nickel alloy pipe
ASTM B210, Tempers O and H112: Aluminum alloy pipe (“O” indicates annealed material “H112” indicates strain-
hardened material)
In addition to pipe, piping systems consist of fittings (elbows, tees etc.), flanges and valves. Material designations of
piping system components (other than pipe) are presented here.
Piping Specifications (also known as “Piping Materials Specifications” or “Piping Class”) provides detailed information
on materials to be used for components of a piping system under certain conditions of temperature, pressure and fluid
being serviced. An example of Piping Specification is shown in Figure 6.2. Piping specifications also contains
information on required wall thickness, corrosion allowance, and Post Weld Heat Treatment (PWHT) and Radiographic
Examinations. Piping Specifications are designated by alphanumeric representation such as A1, A2. These
designations form part of the “Piping Line Number” on Piping and Instrumentation Diagrams (P&IDs), Piping Isometrics
and other documents. A typical piping line number is 10” – PG – 0008 – A1. 10” is the Nominal Pipe Size (NPS), PG is
the service designation, which, in this case, is Process Gas, 0008 is the line sequence number and A1 is the piping
specification.
The selection of appropriate material for a given application involves the consideration of the following aspects:
Process Requirements: Process requirements include pressure, temperature and the corrosion characteristics of the
fluid being handled. Corrosion characteristics of the fluid being serviced play a major role. Carbon Steel piping should
be adequate for non-corrosive substances as long as the temperature is not very high (less than 300°C or 572°F). For
corrosive substances at normal temperature a lined pipe can provide satisfactory service. Stainless steel pipe is the
preferred choice for corrosive substances and also for high temperature service. For pipes handling corrosive fluids,
adequate corrosion allowance must be indicated in the piping specifications. It is very important to note that codes
usually do no provide guidelines on how to select materials for specific service conditions. For example, the following
statements are found in ASME B31.3 concerning material selection: “Compatibility of materials with the service and
hazards from instability of contained fluids are not within the scope of this code”. “Selection of materials to resist
deterioration in service in not within the scope of this code”.
Mechanical Design: Mechanical design involves ensuring the mechanical integrity and safety of piping systems and
pressure vessels. Mechanical design considers the following parameters:
The codes usually have guidelines and formulas related to mechanical design since codes are primarily concerned
with mechanical integrity and safety aspects. Some of the important aspects of mechanical design are the calculation
of minimum required wall thickness for pressure piping and specifying appropriate class of flanges. The “Piping
Specifications” or “Piping Class” discussed earlier is an outcome of mechanical design.
Economics and Availability: Cost is a very important factor in material selection. Different material options must be
evaluated on the basis of “life-cycle” costs. For example, it may be cheaper to replace corroded tubes in a heat
exchanger as compared to specifying a very expensive tube material. Procurement of expensive, high alloy steels may
be difficult and can cause delays in the project. Sometimes, materials may not be available exactly in the form required
which can force the specification to be revised.
The materials being procured for a project have to meet the engineering and design requirements. Material vendors
usually provide this confirmation through documents such as:
Test Certificates
Material Test Reports (MTRs)
Certificates of Compliance
The materials procurement department should have quality checks in place to assure the quality of incoming material.
Quality Assurance (QA) activities can range from visual inspection, verifying data stamped on commodities to random
testing in detail.
LINEAR CONVERSION
Inches to Millimeters
(1 inch = 25.4 millimeters)
Source: “Piping Guide: Second Edition”, Sherwood, David R Whistance, Dennis J, Syentek Book Co. 1991.
Source: “Pipe Drafting and Design”. Parisher, Roy A and Rhea, Robert H, gulf Publishing, 2002.
The Engineering Institute of Technology (EIT) is dedicated to ensuring our students receive a world-class education and
gain skills they can immediately implement in the workplace upon graduation. Our staff members uphold our ethos of
honesty and integrity, and we stand by our word because it is our bond. Our students are also expected to carry this
attitude throughout their time at our institute, and into their careers.