Problem Set 1.

Materials and Fabrication Selection

(Plant design and economics for chemical engineers)

Name: Camaro, Franz Patrick

Course and Year: BS ChE – 5

Date: June 19, 2021

Group Name: Team 1

Co-members: Agoylo, Reina Niña Grace

Lapuz, Jurgen Joseph
Navarro, Jenny
Timbang, Alexandria
Problem 10.5

Table below shows the selected available tanks suitable for each available material for
storage.

Tank Suitable Material for the Tank

Brass-lined H2O (Water)

Carbon-steel 98% Sulfuric Acid

Concrete 20% Hydrochloric Acid

Nickel-lined 10% Caustic Soda

316 Stainless 75% Phosphoric Acid

Wood Vinegar

Brass-lined tanks are composed mostly in copper alloys and less zinc alloys. Copper is highly
reactive with acids in the presence of either oxygen or any oxidizing agents. Thus, sulfuric acid,
hydrochloric acid, vinegar (if pure acetic acid) and phosphoric acid are highly reactive to copper
which would be very corrosive to the tank. However, copper, as the main construction material
for tanks, resists most organic solvents as well as aqueous organic solutions. Brass-lined tank is
suitable for Water and also suitable, but with controlled condition, in caustic soda and Vinegar (if
crude acetic acid, or in aqueous solution).Thus, water would be more suitable for brass-lined
tank.

According to the study of Tang et. al., the corrosion rate increases when HCl or hydrochloric
acid concentration increases. In this case, hydrochloric acid is reactive to carbon steel material,
thus corrosion would occur. According to table 10-8, pure acetic acid can also corrode the
carbon-steel tank. Phosphoric acid and crude acetic acid can also be suitable but with controlled
conditions; with that, sulfuric acid would be more suitable in carbon steel tanks.

Concrete is a mixture of cement, water, sand, and gravel. Cement is a major composition for
concrete. Cement can be made of phenolic and furan resins, polyesters, sulfur, silicate, and
epoxy-based materials. Specifically, Sodium –silicate cements provide good protection against
acids. Thus, hydrochloric acid is more suited to concrete tanks.

Nickel-lined tanks should be used for storage of caustic soda. From Table 10-8 of Timmerhaus
and West, it can be observed that among the materials listed, only caustic soda was acceptable
for storage in nickel-lined vessels. Nickel-lined vessels are found to be unsuitable for 98%
sulfuric acid, and were cautioned for hydrochloric acid and phosphoric acid storage. Additionally,
among the available tanks, nickel-lined tanks were evidently most suitable for caustic soda
storage.

Wooden tanks should be used for storage of vinegar. In a 1942 study by the US Department of
Agriculture, wood tanks were exclusively used for processing and storing of vinegar particularly
because of wood’s resistance to acid. Stored vinegar was also found to be free from
contamination quite probably due to wood being inert (Ireland, 2016).

316 SS tank is selected for 75% phosphoric acid. 316 SS tanks are known to exhibit excellent
anti-corrosive properties in general. In fact, these are highly sought out for the storage of
hazardous industrial chemicals. Among the materials listed, vinegar and water could be stored
excellently in 316 SS tanks. However, more suitable storage tanks were already selected for
these substances. Among the other materials, HCl and H2SO4 can be stored within 316 SS but
is greatly cautioned. Storing caustic soda and phosphoric acid in 316 SS tanks showed minor
effects to the materials. Nickel-lined tanks were already selected for caustic soda. That leaves
us with phosphoric acid. For phosphoric acid, type 304 SS and type 316 SS are found to be
satisfactory for concentrations up to 85% with 316 SS being more resistant to phosphoric acid
than 304 SS (Nickel Development Institute, n.d)

References:
Design Guidelines for the Selection and Use of Stainless Steel. Retrieved from
https://nickelinstitute.org/media/1667/designguidelinesfortheselectionanduseofstainlesss
Teels_9014_.pdf
Ireland, C. (2016). Wood Storage tanks: history, problems, and maintenance. Retrieved
from https://www.sme-usa.com/blog/wood-storage-tanks

Tang, J., Shao, Y., Zhang, T., Meng, G., & Wang, F. (2011). Corrosion behaviour of
carbon steel in different concentrations of HCl solutions containing H2S at 90°C. Corrosion
Science, 53(5), 1715–1723. doi:10.1016/j.corsci.2011.01.041

Problem 10.8

What materials of construction should be specified for the thiophane process-described in Prob.
3-16. Note the extremes of temperatures and corrosion which are encountered in this process
because of the regeneration step and the presence of H2S and caustic.

GIVEN:

1.44 × 10-2 kg/s of thiophane

Essential reaction:

Ratio: 1.5 mol H2S to 1 mol THF

Temperature1: 672K

Temperature2: 300K

Pressure: 207 kPa

Assumptions:
 85% operating factor

80% conversion in the reactor

90% recovery after the reactor

Heat of Formation:

Species ΔfH⦵, kcal/gmol

THF – 59.4

H2S – 4.77

Thiophane – 17.1

Physical Properties:

Species Molecular Weight Specific Gravity Boiling Point Vapor Pressure (25 °C)

THF 72 0.887 65 °C 176 mmHg

Thiophane 88 121 °C

REQUIRED:

(1) Materials of construction for the thiophane process-described in Prob. 3-16

SOLUTION:

Based on the thiophane production process described in Problem 3 - 16, the best
material to use for preheating and cooling is 304 stainless steel. This type of stainless steel is
commonly used around the world and in different chemical process industries since it has
excellent corrosion resistance and value. The 304 stainless steel can be exposed continuously
without substantial scaling at a maximum temperature of 899 °C. In addition, it is a low – carbon
variation of type 302 and it minimizes carbide precipitation during welding. Carbide precipitation
usually occurs in certain stainless steels in a temperature range of 427 - 899°C which causes a
loss of toughness and will make the steel subject to intergranular corrosion in certain
environments but 304 stainless steel is an exception (Nickel Institute, 2020).

Hydrogen sulfide is highly corrosive, therefore, 304L stainless steel is to be used in the
reactor. This type of stainless steel resists acids well at moderate temperatures and
concentrations (Nickel Institute, 2020). It can also be exposed continuously without substantial
scaling at a maximum temperature of 899°C.

Equipment encounters embrittlement or the loss of room - temperature toughness. In

order to handle this type of equipment carefully and to avoid impact during the cooling of
reaction vapors, 304 stainless steel is the best type of stainless steel to be used. There is a
minor loss of toughness in 304 stainless steel compared to other types of stainless steel (Nickel
Institute, 2020).

Since 304 Stainless steel is described to be a material good for general purpose, it is
also the material that can be used for phase separation. 304 Stainless steel is the most
common austenitic stainless steel, which is the most corrosion resistant type. It has good
forming and welding properties, and great toughness even at low temperatures.

Sodium hydroxide is generally highly corrosive to metals, however, caustic soda has a
low corrosion rate at all concentrations for up to about 65°C. Additionally, 304 stainless steel
exhibits a low corrosion rate for boiling caustic soda at concentrations up to 20%. So as long as
these conditions are met, 304 stainless steel is the best material for the caustic washing
(Titanium - Corrosive Media, 2002).

Since the feed for the batch distillation is caustic-treated triophane, it is reasonable to to
use a material for the column that is highly resistant to alkaline media. Titanium has gained
importance due to its strength and medium weight. Additionally, it generally exhibits low
corrosion rates regardless of concentration. On the down side, it is hard to form and weld to
desired shape.

Problem 10.9
Liquid chlorine is to be transferred from a chlorine storage container by pressurizing with dry
chlorine gas. What materials of construction should be selected for this transfer process? What
corrosion effects may be anticipated? How might they be minimized?

Given:
● Liquid chlorine
● Dry chlorine gas

Required:
a. Materials of construction be selected for this transfer process
b. Corrosion effects
c. Minimize effect
Solution/Answer:

a. For liquid chlorine:

Based on Table 10.8 Corrosion resistance of construction materials. It is safe to use
industrial glass and phenolic resins (Haveg) and to use Carbon (Karbate) with caution
depending on conditions.
For dry chlorine gas:
Based on Table 10.8 Corrosion resistance of construction materials. It is safe to use iron
and steel, cast iron (Ni-resist), stainless steel 18-8 Mo, nickel, monel, red brass, aluminum,
industrial glass, carbon (Karbate) and phenolic resins (Haveg). Use stainless steel 18-8
with caution depending on the conditions.
 b. The oxidizing effect is caused by the hydrogen splitting up with water which results in the
release of the hydrogen chloride and nascent oxygen. This causes corrosion of the
material.

c.
● control the amount in the air
● Use a corrosion-resistant exhaust ventilation system separate from other ventilation
systems.
● Avoid High temperatures ( temperatures above 52°C)
● Highly reactive. Reacts explosively with: many chemicals, including, alcohols (e.g.
ethanol), ammonia, saturated hydrocarbons (e.g. butane), aldehydes (e.g.
acetaldehyde), metals (e.g. aluminum), ethers (e.g. diethyl ether). Corrosive to:
aluminum alloys, carbon steel, and other metals.

References:

Department of Health. The Facts About Chlorine. (n.d.).

https://www.health.ny.gov/environmental/emergency/chemical_terrorism/chlorine_tech.htm

Government of Canada, C. C. for O. H. and S. (2021, June 18). (none). Canadian Centre
for Occupational Health and Safety.
https://www.ccohs.ca/oshanswers/chemicals/chem_profiles/chlorine.html.

Peters, M. S., Timmerhaus, K. D., & West, R. E. (2006). Plant design and economics for
chemical engineers. McGraw-Hill.

Nickel Institute. (2020). Retrieved 18 June 2021, from https://www.nickelinstitute.org.

Titanium - Corrosive Media. (2002). Retrieved 18 June 2021, from

https://www.azom.com/article.aspx?ArticleID=1239