API 653 Code Requirements 5

Question 1

Per API 653, what is the maximum allowable out-of-plumbness (tilt) for an existing tank shell before corrective action is required?

Accepted Answer

1 inch per 10 feet of shell height, not to exceed 5 inches total

Answer

API 653 limits out-of-plumbness to 1 inch per 10 feet of shell height with a maximum of 5 inches total before the condition requires evaluation and corrective action.

Question 2

Under API 653, which non-destructive examination (NDE) method is typically used for detecting bottom plate laminations?

Accepted Answer

Ultrasonic testing (UT)

Answer

Ultrasonic testing is the primary NDE method used to detect internal laminations within tank bottom plates.

Question 3

According to API 653, when evaluating a tank for settlement, what type of settlement is most critical and likely to cause structural damage?

Accepted Answer

Differential settlement, particularly localized shell settlement

Answer

Localized differential shell settlement is the most critical type because it can cause shell distortion, weld cracking, and bottom plate damage.

Question 4

Per API 653, what welding process qualification requirements apply to welders performing repairs on API 653 tanks?

Accepted Answer

Welders must be qualified under ASME Section IX or AWS D1.1

Answer

API 653 requires welders to be qualified in accordance with ASME Section IX or AWS D1.1, per the applicable welding procedure.

Question 5

What is the significance of the 'critical zone' at the tank bottom as defined in API 653?

Accepted Answer

The annular plate ring within 3 inches of the shell-to-bottom weld

Answer

The critical zone is the annular bottom plate area within approximately 3 inches of the shell-to-bottom junction weld, subject to heightened inspection requirements due to stress concentrations.

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

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

API 653 Code Requirements 5