API 653 Pressure Testing 3

Question 1

Under API 653, a pneumatic pressure test may be used instead of a hydrostatic test only when:

Accepted Answer

The owner/operator can demonstrate that water would damage the tank or process

Answer

API 653 permits pneumatic testing only when the owner/operator documents that introduction of water is not practical due to process contamination or structural concerns.

Question 2

What is the primary safety hazard associated with pneumatic pressure testing of storage tanks compared to hydrostatic testing?

Accepted Answer

Energy stored in compressed gas greatly exceeds that of liquid under the same pressure

Answer

Compressed gas stores far more energy per unit volume than liquid under the same pressure, making pneumatic test failures catastrophically more energetic than hydrostatic failures.

Question 3

According to API 653, what document must the owner/operator prepare before conducting a hydrostatic test on a reconstructed tank?

Accepted Answer

A written test procedure reviewed by the engineer of record

Answer

API 653 requires a written hydrostatic test procedure to be prepared and reviewed by the engineer of record prior to testing.

Question 4

When a tank bottom is tested using a vacuum box test per API 653, what is the minimum vacuum level (negative gauge pressure) that must be achieved?

Accepted Answer

3 psi (21 kPa)

Answer

API 653 requires a minimum vacuum of 3 psi (21 kPa) for a vacuum box test to be considered effective for detecting bottom weld leaks.

Question 5

For a reconstructed tank, API 653 requires the hydrostatic test to be witnessed by:

Accepted Answer

An authorized inspector (AI)

Answer

API 653 requires an authorized inspector (AI) as defined by the standard to witness the hydrostatic test on a reconstructed aboveground storage tank.

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

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

API 653 Pressure Testing 3