API API Pressure Vessels & Storage Tank Standards

Question 1

API Standard 650 applies to which type of petroleum storage vessels?

Accepted Answer

Welded aboveground steel tanks for oil storage at or near atmospheric pressure

Answer

API Std 650 covers the design, fabrication, erection, and testing of welded steel aboveground storage tanks operating at atmospheric or low pressure.

Question 2

What does the 'design pressure' of a pressure vessel represent under ASME/API standards?

Accepted Answer

The maximum allowable working pressure (MAWP) used as the basis for vessel design

Answer

Design pressure equals or exceeds the maximum allowable working pressure and is the pressure at which vessel wall thickness and component ratings are calculated.

Question 3

According to API Standard 510 (Pressure Vessel Inspection Code), the risk-based inspection (RBI) approach prioritizes inspection resources based on:

Accepted Answer

A combination of the likelihood of failure and the consequence of failure

Answer

API 510 RBI methodology ranks vessels by combining probability of failure (corrosion, damage mechanisms) with consequence of failure (safety, environmental, business impact).

Question 4

In API Std 650 tank design, the 'one-foot rule' is used to calculate shell thickness at:

Accepted Answer

One foot above the bottom of each shell course to account for hydrostatic head

Answer

The one-foot rule calculates the required shell thickness at a point one foot above the lower horizontal seam of each shell course, reflecting hydrostatic liquid pressure.

Question 5

Which inspection method is most commonly used to assess the floor thickness of an in-service aboveground storage tank without emptying it?

Accepted Answer

Magnetic flux leakage (MFL) floor scanning

Answer

MFL floor scanners detect corrosion-induced metal loss in tank floors while the tank is in service or after emptying, without requiring full entry.

(API) American Petroleum Institute Certification Practice Test

(API) American Petroleum Institute Certification Practice Test

API API Pressure Vessels & Storage Tank Standards