The following list will provide a few interview questions asked in the different interviews for a Piping Engineering (Stress) position. Answers to most of the questions are added here for reference. I hope you will be able to find remaining answers from ASME B 31.3 and any piping engineering textbooks or from the piping handbook. In case you could not find out a specific answer reply in the comments section.
Kind request to Readers to list other questions that you might have faced/ received in some interviews in the comments section to help fellow colleagues.
1) How to make a critical line list or flexibility log? How will you decide the critical line list with help of ASME B31.3?
2) How to decide Stress critical systems for analysis using Caesar II?
3) Which lines can be eliminated from formal Stress analysis?
4) Can you make a typical Sketch including supporting for column piping? How to decide how many load-bearing clip-supports to be used?
5) Draw a typical Sketch & supporting arrangement for tank farm piping? How tank Piping analysis is different from normal pressure vessel connected piping system analysis?
6) What is SIF? Formulas for In-plane, out plane SIF for elbow as per ASME-B31.3?
7) Value of SIF, Flexibility factor for Bend?
8) What are the necessary documents required for stress analysis?
9) Why a Spring hanger is used? Can you write the formula for spring HL, CL & variability?
10) What are the different types of supports used in piping systems?
11) What do you know about Expansion joints and their types? When these come into the picture?
Ans: //whatispiping.com/design-considerations-expansion-bellow. Refer EJMA for more details.
12) What are the normal types of load cases? Write the load cases for a typical stress system using a static method of seismic and wind?
13) What is slug flow? What parameters are required to calculate the Slug force? How do you perform Slug flow analysis using Caesar II? Do you design for vibration arresting along with slug?
14) What are the dynamic restraints? What is snubber and when do you use a snubber?
15) What is the minimum swing allowed in the top-mounted hanger? What will you do if that amount exceeds in a typical piping system?
16) What is cold pull and why it is used?
17) What is the difference between Variable Hanger and Constant Hanger? What is the variability of Constant Spring hanger?
18) What are the inputs required for stress analysis? What do you check in Caesar’s analysis of a piping system?
19) What do you mean by the term “liberal stress”?
20) What is hot-cold philosophy (operating- standby philosophy) for a pump? Have you heard the term Pump alignment? How do you ensure proper alignment of pumps with piping while analysis? What consideration do you make?
21) Write the equation for SE in terms of Sb and St from ASME B 31.3?
22) What is the major difference between WRC 107 and WRC 297?
23) How Anchor load for a rack is calculated at the initial phases of the project? What are the normal guidelines assumed?
24) Draw a typical control station layout and show its support?
25) How pump piping is routed and supported?
26) How you will decide the position of anchor bay in rack piping?
27) Which side (suction or discharge) in the case of a pump piping system is more critical from a stress point of view? Justify the answer?
28) What are the main factors that decide the support span?
29) What does API 610 explain about allowable nozzle loads for a Centrifugal Pump?
30) Can you show the typical layout and support for PSV lines?
31) What is the effect of friction in Piping stress analysis?
32) How the layout of a pump piping changes with changes in temperature?
33) Why the allowable for primary stress is different from that of secondary stress?
34) Is the stress due to the seismic anchor movement occasional stress? Explain with proper reason?
35) What is meant by the sentence ”primary stress is not self relieving but secondary stress is”? Explain in detail the meaning of the term “ self relieving”.
36) Will SIF increase or decrease with an increase in pressure, other parameters kept constant? Justify your answer.
37) What is the role of the ‘Y’ factor in the pressure thickness equation of B31.3 and B31.1?
38) Is the pressure thickness equation for bends the same as that of a straight pipe in B31.3?
39) How B31.3 defines the terms Weldolet, Sweepolet?
40) Between a short and a long radius bend, which one has higher flexibility and why?
41) What does B31.3 tell about SIF for sockolet and reducer?
42) Explain the role of Appendix V of B31.3?
43) Does B31.3 allow a stress limit of 1.33Sh in the PSV pop up case or is it 1.20 Sh?
44) Explain how to model a snubber in CAESAR II.
45) Briefly explain the modeling of Sway Brace is CAESAR II.
46) What is the basic difference between a snubber and a sway brace in terms of applicability? Have you used these restraints during your analysis?
47) Explain with a reason as to what should happen to the SIF and Flexibility factor of a bend when a trunnion is attached to it?
48) Explain the terms SIF and FLEXIBILITY factor.
49) Why SIF is “not so significant” with primary loading?
50) What happens to SIF of a reinforced connection if the thickness of reinforcement increases beyond 1.5 times header thickness?
51) What special note does B31.3 provide for SIF of welding tees (B16.9)?
52) Explain with reasons as to which one is having higher SIF: a 45 bend or a 90 Bend?
53) Explain with reasons as to whether for a non-90-degree branch the same SIF can be taken as that for a 90 branch?
54) If the thickness of the header of a branch connection increases, what happens to its SIF, other parameters kept constant?
55) What are the methods for flange leakage checking? Write equations used for flange leakage checking in the pressure equivalent method?
56) What are the major differences between ASME B 31.3 and B31.1?
57) Place the following lines in Rack and show the placement of the expansion loop?
- a) A 16 inch High pressure steam line
- b) A 6 inch Low pressure steam line
- c) A 10 inch Medium pressure steam line
- d) A 30 inch flare line
- e) A 8 inch process line and
- f) A 24 inch cooling water line.
58) How to decide the Spring height for a top-mounted Spring hanger? What are the attachments used?
59) How do you calculate SIF for 45-degree lateral connections entering into a flare header?
60) What are the transfer lines? Why does the stress analysis of transfer lines are considered as critical?
61. If a power plant is designed inside a Process refinery then where the specification break between ASME B31.1 & ASME B31.3 should occur?
62. What is the category M fluid service? Provide some examples?
63. What will be the consequences of a steam piping having a low pocket but not having a steam trap?
64. When and why the reducer of a pump suction piping is installed in bottom flat condition?
65. If you found a specification break (at flange) between carbon steel and stainless steel in a typical P&ID. What are the additional arrangements which a piping engineer should make for this?
66. Assume a straight pipe of length L anchored at both ends. When a temp change occurs the anchor force at one anchor becomes F1. Now the length of the same pipe increased to L2 and with similar temp change anchor force becomes F2. What is the relation between F1 and F2?
67. What is the Piping Speciality item? How many types of piping specialty items are used in piping engineering? Can we include them in the standard piping specification, explain with reason?
68. Why does the sustained sagging for steam lines are limited within 2.5 mm?
69. What is a “Double block & Bleed” valve? When such type valves are required?
70. In a normal tie-in where do you insert the spectacle blind? a) before block valve and towards new plant or b) after block valve and towards existing plant . Explain why.
71. What is the difference between a pipe elbow and a bend?
72. Among the following which material has the highest coefficient of thermal expansion? A) Carbon steel b) Cast Iron c) Duplex steel d)Stainless steel e) Galvanized Carbon steel
73. What are the major parameters to be reported in support tag for a Shoe/Saddle type support?
74. What are the Metallic expansion joints? When they are used and when they could be avoided?
75. What is hot sustained stress? Why do we check it? Do we need to check expansion stress for the hot sustained cases?
76. What is the philosophy of arranging pipes in the Pipe rack and why? Normally what % of the area is kept reserved for future expansion?
77. What are the major difficulties faced by a stress engineer while analyzing two vertical reboilers connected with a single column?
78. What are the different types of combination methods available is Caesar II? What is the difference between the Scalar and Absolute method?
79. Are process plant water lines considered pressure piping systems?
80. For what fluid service category may a hydro test be waived off as per B31.3?
81. Check the following load cases and tell me what is the difference between load case L3 and L4?
- L1. W+T1+P1 OPE
- L2. W+P1 SUS
- L3. L1-L2 EXP
- L4. T1 EXP
82. Which comes first?–Stress or Strain?
83. What is the difference between Stress and Pressure?
84. What are the major differences between a Pipe and a Tube?
85. What is seismic co-efficient? How this is decided?
86. What is the wind shape factor? How the value of wind shape factor is decided?
87. Why does the manufacturer produce pipes with OD constant for a specific size and varying ID?
88. What are the major responsibilities of a stress engineer?
89. What are the major differences between primary and secondary loads in Piping?
90. Do you consider the vertical thermal growth for modeling fired heater in Caesar II? Explain with reason?
91. Why does the dummy of a piping system is also insulated for a cold insulated piping system but not insulated for the hot insulated piping system?
92. What are the major parameters and process inputs required for performing dynamic slug flow analysis?
93. Which parameters do you seek from the civil department for performing underground piping analysis in Caesar II? Describe briefly the method of performing underground piping analysis using Caesar II? What are the outputs to check and what to interpret from caesar results?
94. How to calculate pipe thickness for an externally pressured piping systems?
95. What do you mean by the term flexibility? How to ensure that the flexibility of a piping system is appropriate? What are the means for increasing flexibility? What will happen if more flexibility is provided to a piping system?
96. As per code ASME B 31.3, how many types of fluid service is available?
97. What are the code cases for ASME B 31.3?
98. Describe step by step methods for modeling a sway brace in Caesar II?
99. In which way PDS, PDMS, and SP3D differ? Which one is the best user friendly?
100. How to calculate the piping stress man-hour for a specific project?
101. Can we exceed the design pressure of a piping system more than its design pressure? If yes then in what condition?
102. What is the limitation of using the PTFE slide plate? What can be done in such a situation?
103. How to decide whether a hydro test or pneumatic test will be performed for a piping system?
104. What is the bourdon effect of a Piping system? When this effect become critical?
105. How do you check dummy or trunnions for any project? Can you write the formulas used for this checking?
106. What is the difference between the pressure safety valve and the pressure relief valve?
107. Why do you consider slug flow in a piping system as critical?
108. What is the function of a gasket in a flanged joint?
109. Why sustained stress is considered as primary stress?
110. What are the major differences between SIF and SCF (Stress Concentration Factor)?
111. Let’s assume from a 24-inch pipe header two tappings, one 2 inches, and another one 4 inches, are taken. At the interconnection point in which case the SIF will be higher?
112. What is the industry-accepted procedure for transferring anchor load for intermediate anchors (anchor in between two loops) where normally caesar shows very less value?
113. How to analyze stress packages when a D/T ratio for the pipe exceeds 100?
114. Arrange the following piping elements with respect to flexibility and SIF (either increasing or decreasing order). Assume pipe size and thickness are constant.: 1.5D bend, 1D bend, Straight Pipe, 4D bend, 10D bend.
115. What is primary membrane stress?
116. Which one is more flexible: 45° bend or 90° bend? Which one is having more SIF?
117. Can we call piping shoe a pipe component as per code? Explain with reason. What is your opinion about the RF pad in this respect?
118. What does the piping code say about the operation and maintenance of the piping system?
119. You want to make some changes in the existing plant and want to add a new line by hot tapping. From which point the ASME B 31.3 code will be applicable?
120. What are the terms Code Case and Code Interpretation signifies?
121. How to model Air fin Fan Cooler in Caesar II? Why do you consider equipment weight in AFC modeling while for other heat exchangers we do not consider? What code need to be followed for nozzle load checking and what the code says about nozzle load checking? Why do we need thrust blocks for air fin fan cooler?
122. Can you write the NEMA equipment nozzle equation sets? What are the major differences between API 617 and NEMA SM 23 from the stress point of view? Draw a typical steam turbine piping layout?
123. Which standard is used for designing a plate-fin heat exchanger? Which table is normally followed for nozzle load checking?
124. How do you consider tank settlement while piping stress analysis? Is it primary or secondary stress? Do you add tank settlement with sustained load cases? If yes why? What code says about tank settlement? What is tank bulging and why does it happen?
125. Draw a typical layout of a line connected with a fired heater (Heater Piping)? Which standard is used for allowable nozzle loads?
126. What are the major differences between B 31.3 edition 2018 and 2016?
127. Which standard says about rotary equipment alignment check? What are the criteria mentioned in that standard? While alignment checking spring will be in locked or design condition?
128. Calculate the number of loops for a 400-meter long carbon steel pipe having a temperature of 400-degree centigrade running over a pipe rack?
129. How do you calculate PSV reaction forces in the absence of reaction force in vendor data? What is the major difference between the pressure safety valve and the pressure relief valve?
130. Do you perform a trunnion check while analyzing a stress system? What are the associated formulas for trunnion checking?
131. What is the equation for calculating seismic co-efficient? How to calculate the wind force?
132. What is a guided cantilever method? What is the importance of this method?
133. What does Appendix F of API 610 ensure? What are the equations? What does the standard say for vertical inline pumps?
134. What do you mean by weld joint strength reduction factor and quality factor? What is the importance of these factors?
135. While providing preliminary rack loading what assumptions do you consider?
136. What was the most critical system you analyzed in the last company? Draw the layout? What changes did you recommend? What is the temperature and pressure of that line?
137. What are the minimum load cases required to consider while performing a stress analysis of a vertical reboiler connected piping system?
138. Have you performed a stress analysis of reciprocating compressor connected lines? What are the considerations? What is the minimum frequency you achieved before sending for a pulsation study? How do you consider up to what length of piping is to be sent for pulsation study?
139. What actually do you check during flange leakage checking by NC 3658 method?
140. Can we reduce the hydro-test pressure of pipe to less than 1.5 times the line design pressure? If yes then in what condition?
141. What do you mean by the term Flow-Induced Vibration or FIV?
142. What is AIV? What are the differences between FIV and AIV?
143. How to Calculate Length, Angle of Cut, Weight, and Cut-back of the Miter for a Miter Bend?
144. How to Calculate Tank Dike Wall Height?
145. What are the differences between ASME B 31.4 and ASME B 31.8?
146. What is the meaning of Pressure Temperature Rating and Flange rating of ASME Flanges?
147. What are the differences between Seamless and Welded Pipe?
148. What are the major Considerations for Storage Tanks Nozzles Orientation?
149. Have you used Flexible Sleeve Coupling in Stress Analysis?
150. Have you heard the term Rupture Disk? How it differs from a PSV?
151. What is Flange Insulation Gasket Kit? Why are these used?
152. How do you model the supports of large diameter pipes for example say 42 inch pipe?
153. What are the differences between Piping and Pipeline?
154. Have you come across the term “Barred Tee”? How does it differ from a normal Tee?
155. What is Pipe Thermal Bowing?
156. What is the meaning of Surge or Water Hammer in the Piping System?
157. What are the main differences between API 650 and API 620 tanks?
158. What are the different types of Stresses in a Piping System?
159. Have you ever performed the stress analysis of Surface laid pipelines?
160. Can you tell the differences between ASME B 16.47 Series A and Series B flanges?
161. What is the meaning of Piping MTO?
Few more piping stress interview questions with answers for you..