API 653 Material Evaluation 2

Question 1

When evaluating shell plate corrosion, which measurement technique is preferred for determining the minimum thickness in a corroded area?

Accepted Answer

Ultrasonic thickness measurement (UT)

Answer

Ultrasonic thickness measurement is the preferred method for accurately determining remaining wall thickness in corroded areas without requiring tank entry.

Question 2

According to API 653, what is the term for the minimum shell thickness required for structural integrity at a given liquid level?

Accepted Answer

Calculated minimum thickness (tmin)

Answer

API 653 uses 'calculated minimum thickness' (tmin) to define the lowest acceptable thickness for a given course at a specified liquid level.

Question 3

A tank shell plate has a measured thickness of 0.285 inches. The tmin calculated per API 653 is 0.250 inches. What is the corrosion allowance remaining?

Accepted Answer

0.035 inches

Answer

The remaining corrosion allowance is the difference between measured thickness and tmin: 0.285 − 0.250 = 0.035 inches.

Question 4

Which standard is most commonly referenced for the material toughness requirements of shell plates used in low-temperature service tanks?

Accepted Answer

API 650 Appendix A

Answer

API 650 Appendix A addresses low-temperature and cold-service design requirements including material toughness for tanks operating at reduced temperatures.

Question 5

When assessing a pitted area on a tank bottom, the critical dimension used for remaining strength calculations is the:

Accepted Answer

Remaining wall thickness at the deepest pit

Answer

The remaining wall thickness at the deepest pit location governs the fitness-for-service assessment because that represents the minimum metal available.

(API 653) API 653 Aboveground Storage Tank Inspector Certification Practice Test

(API 653) API 653 Aboveground Storage Tank Inspector Certification Practice Test

API 653 Material Evaluation 2