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

High-pressure spherical pressure vessels for LPG

Answer

Underground fiberglass reinforced plastic tanks

Answer

Cryogenic storage tanks for LNG service

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

The operating pressure during normal production conditions

Answer

The hydrostatic test pressure applied during commissioning

Answer

The emergency relief valve set pressure

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

Only the age of the vessel since last inspection

Answer

The original fabrication code used to build the vessel

Answer

The number of pressure relief valve activations recorded

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 top shell course where wind load governs

Answer

The roof-to-shell junction for wind uplift calculations

Answer

The nozzle reinforcement zone at one foot from the centerline

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

Radiographic testing (RT) from the roof manway

Answer

Liquid penetrant testing (PT) of the shell

Answer

Visual inspection from inside using a camera drone

Question 6

The 'corrosion allowance' added to calculated pressure vessel wall thickness serves to:

Accepted Answer

Extend the operational life of the vessel by providing extra metal for expected corrosion

Answer

Increase the safety factor for mechanical overpressure events

Answer

Compensate for weld joint efficiency below 1.0

Answer

Account for thermal expansion at elevated operating temperatures