API 510 Pressure Vessel Design & Fabrication Standards 2 — Questions and Answers
Question 1: According to ASME Section VIII Div. 1, what is the minimum required thickness formula for a cylindrical shell under internal pressure (thin-wall approximation)?
- t = PR / (SE - 0.6P) (Correct answer)
- t = PR / (2SE + 0.4P)
- t = PD / (2SE - P)
- t = PR / (SE + 0.4P)
Correct answer: t = PR / (SE - 0.6P)
ASME VIII-1 UG-27(c)(1) gives t = PR / (SE - 0.6P) for longitudinal joint stress in cylindrical shells.
Question 2: What joint efficiency (E) applies to a Type 1 butt weld that has received full radiographic examination per ASME Section VIII Div. 1?
- 0.70
- 0.85
- 1.00 (Correct answer)
- 0.90
Correct answer: 1.00
A Category A Type 1 butt weld with full RT per UW-11(a) receives a joint efficiency of 1.00.
Question 3: Under ASME Section VIII Div. 1, which UG paragraph governs the design of formed heads under internal pressure?
- UG-27
- UG-32 (Correct answer)
- UG-34
- UG-37
Correct answer: UG-32
UG-32 covers the required thickness of formed heads (ellipsoidal, torispherical, hemispherical, conical) under internal pressure.
Question 4: A 2:1 semi-ellipsoidal head under internal pressure is being designed per ASME VIII-1. What is the correct head factor (K) used in the thickness formula for a standard 2:1 ellipsoidal head?
- 0.9
- 1.0 (Correct answer)
- 0.87
- 1.2
Correct answer: 1.0
For a standard 2:1 ellipsoidal head, the factor K equals 1.0 per UG-32(d), simplifying the formula to t = PD / (2SE - 0.2P).
Question 5: Which ASME Section VIII Div. 1 paragraph requires that all pressure vessels be provided with at least one pressure-relieving device?
- UG-125 (Correct answer)
- UG-100
- UG-99
- UW-51
Correct answer: UG-125
UG-125 mandates that every pressure vessel must be protected by at least one pressure-relieving device.
Question 6: What does the designation 'SA-516 Gr. 70' indicate for a pressure vessel shell plate?
- ASTM plate steel with 70,000 psi minimum ultimate tensile strength (Correct answer)
- An alloy steel with 70 Brinell hardness
- A stainless steel with 70% chromium content
- A carbon steel with 70 ksi yield strength
Correct answer: ASTM plate steel with 70,000 psi minimum ultimate tensile strength
SA-516 Grade 70 is an ASME-accepted carbon steel plate with a minimum tensile strength of 70,000 psi, commonly used for pressure vessel fabrication.
Question 7: Per ASME Section VIII Div. 1, a vessel designed for external pressure must be checked for what primary failure mode?
- Creep rupture
- Elastic or inelastic buckling (collapse) (Correct answer)
- Stress corrosion cracking
- Fatigue due to cyclic loading
Correct answer: Elastic or inelastic buckling (collapse)
External pressure design per UG-28 and UG-33 primarily guards against elastic or inelastic buckling (collapse) of the shell.
API 510 Pressure Vessel Design & Fabrication Standards 2
According to ASME Section VIII Div. 1, what is the minimum required thickness formula for a cylindrical shell under internal pressure (thin-wall approximation)?