International Conference on Production and Mechanical Engineering (ICPME2014) Dec.

30-31, 2014 Bangkok, Thailand

A survey of GRP Pipes Defects and Damage

Due to Fabrication Processes
Dr. Saleh R Gashoot1*, Dr. Ramadan A. Al-Madani2
FRP piping industry is around 40 to 50 years old and has vide
Abstract Glass Reinforced Plastics, commonly known by variations both in designs and manufacturing techniques.
various standards, as Fiber Reinforced Plastics (FRP), GRP, Glass GRP materials have been used with increasing frequency
Fiber Reinforced Plastic (GFRP), Reinforced Plastic Mortar Pipe within the petroleum industry during the last 10 years, and are
(RPMP) or Reinforced Thermo-set Resin Plastic (RTRP) is an particularly suited for offshore applications. Compared to
amalgamation of resin, glass fiber, manufactured using appropriate many metallic materials, GRP provides low costs, and faster,
additives and treatment methods. It is a composite engineering
easier installation. The lack of commonly accepted inspection
material uniquely capable of meeting a wide variety of specific
processes and end product requirements of various applications of practices and defect acceptance criteria causes most GRP
fluid transport requirements. users some uncertainty, which typically results in additional
GRP piping system is often utilized in almost all applications costs associated with overly conservative or non conservative
to withstand aggressive service, ambient and environmental responses.
conditions. It has been successfully used in various piping systems If the machine setup is according to the specifications in setup
and applications over the entire world. GRP piping industry in Libya sheet and raw materials are tested and approved, there are
has just started (i.e. since 2009), so such manufacturing plants are normally no problems with defects on pipes. But sometimes
facing some difficulties during commissioning and production trails process variables changes during the production and may
stage. GRP piping industry has wide variations both in designs and
cause defects on pipes. Defects can occur in either the GRP
manufacturing techniques used.
This paper will focuses and discuss the possible defects associated
material or in the mechanical and adhesive bonded joints that
with the production of GRP pipes, from the point of view of human make up a piping system.
error, and or lower manufacturing skinless due to new technology This paper will discuss the possible defects can occur in
introduction in the area. The survey will involve and demonstrate either the GRP material or in the mechanical and adhesive
the usage of GRP for various aggressive fluids and its consequences. bonded joints that make up a piping system involved with
Finally, concluding remarks concerning defect types, causes, and GRP piping systems. Highlights of the past years of
the prevention of such defects will be presented. experience of GRP piping in all applications, indicating that
how GRP piping is performing in vary harsh and aggressive
Index Terms - composite materials, Glass fiber reinforced environments both internally and externally. Also this paper
plastics , GRP piping industry. demonstrates the visually identify defects on pipes, how to
repair them, and suggestions for corrective actions in order to
I. INTRODUCTION avoid these defects.
Glass Reinforced Plastics pipes (GRP Pipe), it is a
composite engineering material uniquely capable of meeting a II. GRP PIP MATERIALS
wide variety of specific processes and end product A. Resin Systems
requirements of various applications of fluid transport
requirements. It has a combinations of properties generally The Manufacturer will use only approved polyester
not found in any other traditional or conventional material, or Vinyl ester resin systems for which he can provide
these include exceptionally high strength to weight ratio (have documented performance in this particular application. The
low thicknesses and high mechanical properties-with stands data shall have been acquired from a composite material of
high pressures), superior corrosion resistance (no scaling and similar construction and composition as the product proposed
no buildup), maintenance free, higher hydraulic efficiency for this project.
(smaller sizes), light weight (lower transportation and
installation costs), higher resistance to surge pressure (more B. Glass Reinforcements
safer under worst conditions due to its low modulus of The reinforcing glass fibers used to manufacture the
elasticity), best joining systems, excellent workability and components shall be of highest quality commercial grade of
design flexibility's. Thus allowing GRP piping to be used for glass filaments suitably treated with binder and sizing
high pressures and in very tough and rough conditions. compatible with impregnating resins of ECR type. The glass
GRP piping system is often utilized in almost all applications reinforcement forms are: C-veil, direct roving, and chop
to with stand aggressive service, ambient and environmental roving. Unidirectional (Axial Tape) glass reinforcement may
conditions. It has been successfully used in various piping also be used.
systems and applications in all of the world.
C. Fillers
1
Silica sand or other chemically compatible fillers may be
University of Tripoli, Faculty of Engineering, Tripoli, Libya
2 used in the laminate.
Al-Jabel Algharbi University, Engineering Faculty, Gharian, Libya
*Email; sabdussalam@aerodept.edu.ly

http://dx.doi.org/10.15242/IAE.IAE1214213 93
 International Conference on Production and Mechanical Engineering (ICPME2014) Dec. 30-31, 2014 Bangkok, Thailand

III. GRPPIPES MANUFACTUREAND CONSTRUCTION In this section will discuss the possible defects
associated with the production of GRP pipes, from the point
The pipes shall be supplied in accordance with diameter of view of human error, and or lower manufacturing skinless
and tolerances according to the design specification. They due to new technology introduction in the area. Also in this
shall be manufactured by controlled, continuous filament part will be concerning the defect types, causes, and the
winding process with a winding angle of 87 to 89 using the prevention of such defects. See as demonstrated in the Table.
materials described in previous section to result in a corrosion 1. Pictures and text in this paper will give an excellent
resistant composite structure to meet the operating conditions presentation about:
for the required project for each pipe diameter. The most 1) visually identify defects on pipes
advanced state-of-the-art process for manufacturing large 2) how to repair them
diameter GRP pipe is the continuously-advancing mandrel 3) suggestions for corrective actions in order to avoid
process. The winder accommodates a range of diameters from these defects.
100mm to 4000mm. The basic winder is composed of a
continuous steel band supported by beams which form a
cylindrically shaped mandrel. The beams rotate, friction pulls
the band around and roller bearings allow the band to move
longitudinally so that the entire mandrel continuously moves
in a spiral path toward the end of the machine. As the mandrel
moves, fine graded filler, glass fibers, resin and surface
materials are metered on in precise amounts under the
direction of a programmable logic controller (PLC) and
computer (PC).
The PLC-PC modules provide integrated process control
Fig.(2) Sequence of evaluation of the defected GRP pipe
based on pre-programmed recipes. Only basic pipe data such
as diameter, pressure and stiffness class needs to be entered
Table.1
and the computer calculates all the machine settings.
DEFINITION CAUSES /
Schematic diagram of continues filament winding is shown in WHAT
VISUAL DEFECT HOW TO
Fig.(1). Material consumption as well as pipe thickness is TO DO?
PREVENT
continuously monitored and logged. The logged data is 1) Craze Star shaped All crazes Sharp impacts
ac-cumulated and reports printed when needed. Stiffening figure on inner have to be or rough
or outer repaired transport or
ribs may be used to increase the overall pipe stiffness. They handling.
surface. with
can be of glass fiber filament-wound or glass fiber woven method no.
roving construction using similar resin as used in the pipe 1
cylinder.
2) Surface void Small air Single Curing speed
pockets or void: If is too high
Roving rack voids beneath >1.5mm (styrene is
Sand & chopped
glass the surface deep or entrapped in
mat. Air >15mm surface).
Release film
pockets can be diam., then
Glass-fibers
broken with repair.
Winder ball pen. Group of
Engine
voids:
Only repair
Surface veil
if there are
Computer & Finished pipe
Dosing pumps
Control panels more than
Daly
Tank
4 voids per
0.1m2 and
Bull tank
diam
<15mm
and depth
Fig.(1) Schematic Diagram of Continuous Filament winding <1.5 mm:
Repair
method no.
1) VISUAL DEFECTS ON GRP PIPE 2.
3)Irregular Spiraling >3mm Steel band not
If the machine setup is according to the specifications in deep: properly
Thickness & Wavy. impressions
setup sheet and raw materials are tested and approved, there near the liner Repair installed, or
are normally no problems with defects on pipes. But surface pipe. 0-3 too high steel
sometimes process variables changes during the production mm deep band tension.
and more
and may cause defects on pipes. Defects can occur in either
than 1/3 of
the GRP material or in the mechanical and adhesive bonded nominal
joints that make up a piping system. Pipe defect action thickness:
sequence with the process or after should be followed as Repair
mention in Fig.(2). pipe.
Repair
method no.

http://dx.doi.org/10.15242/IAE.IAE1214213 94
 International Conference on Production and Mechanical Engineering (ICPME2014) Dec. 30-31, 2014 Bangkok, Thailand

1. REFERENCES
4) Cracks & missing Lines in Adjust the Excess resin
chop circumferential material cured without [1]. Gupta V.B. and Kothari V.K Manufactured Fiber Technology,
direction application glass fiber Chapman & Hall, India, 1992
reinforcement, [2]. Fiberglass Pipe Handbook, Fiberglass Pipe Institute, 1992.
or [3]. Herman E. Mark , Fiberglass Technology , Marcel Dekker,1984.
resin cured at [4]. Stephen R., Introduction to design and analysis with advanced
too high temp. composite materials, Prentice Hall, 1997.
[5]. Hallpain J. C. Primer, on composite materials analysis, Technomic
Co., USA, 1969.
5) Dry & wrinkles Spiraling >3mm Accumulated
[6]. Schwartz M. M., Composite Material handbook, McGraw-Hill Co.,
impressions deep: - Chop glass
1983.
near the liner Repair falls on
[7]. Web-sites Compositeregis.com
surface pipe 0-3 laminate
Filament winding /Advanced Composite Inc_Filamenent winding and
with resin mm deep during
hand lay-up composite manufacturing specialists.htm.
Glass not and more cleaning of
impregnated than1/3 of chopper Filament winding /fiberglass
nom. etc. Filament winding /Filament winding Machines.htm
thickness, - Resin flow is Filament winding/ Textileweb_com Digital Marketplace for the textile
then repair too low or and fabric industry.htm
with viscosity is too
method no. high.
1. Steel band Prof. Saleh R. Abdussalam Gashoot , born in
not properly Libya on
installed, or 25/09/1959. he has awarded the following degrees
too high steel :Ph.D. Mechanical Engineering, Department of
band tension. Mechanical & Industrial Engineering, University of
Adjust Return Manitoba, Winnipeg, Manitoba, Canada. M. Sc.
head Mechanical Engineering, Department of
Mechanical Engineering, Aerospace Option,
McGill University, Montreal, Quebec, Canada. B. Sc. Aeronautical
1)Core delamination Separation of Pipe to be - Too much Engineering, Department of Aeronautical Engineering, University of
layers; repaired, sand Tripoli, Tripoli, Libya.
longer than 25 cut if - Saw impact Over 25 years of successful professional and academic experience. This
mm necessary - Lifting tables experience has taken place in Libya, Canada, and the USA. He spent more
than 20 years in teaching and university management at different universities
in Canada and Libya. In companies management and business, he has been
2) Surface pit All pits Air pockets in directly involved in promoting and opening unique business and investment
Pit > 1.5mm in have to be inner liner or opportunities within Libya. His professional relationships range from
diam and 1.5 repaired outer surface academia to governmental agencies to private commercial enterprises.
mm deep. He has been successfully involved and participated in all aspects of
executive management, strategic planning, start-up initiative, airport
development, business development, and client relationship development.
3) Resin rich Lines in Adjust the Excess resin
He is active in numerous professional organizations and have lectured within
circumferential material cured without
direction application glass fiber these organizations. He also has been privileged to have had numerous
reinforcement, publications throughout his professional career.
or Prof. Abdussalam Gashoot, Saleh awarded many awards some of them are: -
resin cured at - Department of Mechanical and Industrial Engineering Travel Award.1997
too high temp. Faculty of Graduate Studies Travel Award, Canada.
- University of Tripoli:1994 - 1997, Scholarship from University of Tripoli,
Libya.1984 - 1987, Scholarship from University of Tripoli, Libya.
V. CONCLUSIONS - 1979 Training Course at DeHavilland Aircraft & Air Canada.
Finally, Prof. Abdussalam Gashoot Published papers and research work in
GRP piping system is often utilized in almost all the field of aircraft structure, Composite materials, Design, industrial and
mechanical vibration in international conferences and journals.
applications to with stand aggressive service, ambient and
environmental conditions. Hence it is an important issue to
investigate and assessment of the possible defect and damage
that possibly occur to such pipe, especially it has to be
controlled from raw materials , during process and after final
product of GRP pipe completed. In order to save time and
cost in the plant inspection of visual defects and get their
causes and propose the way of preventing becomes an
essential procedure in the production of GRP pipes. So the
main remarks in this paper which gives an excellent
presentation about:
- visually identify defects on pipes
- how to repair them
- suggestions for corrective actions in order to avoid
these defects.

http://dx.doi.org/10.15242/IAE.IAE1214213 95