API 653 Welding Inspection 5

Question 1

Per API 653, when is a hydrostatic test required after completing a weld repair on a tank shell?

Accepted Answer

When a major repair is made to the shell or when required by the authorized inspector

Answer

After every weld repair regardless of scope

Answer

Only when the tank has previously failed a leak test

Answer

Whenever more than three weld repairs are made in a single inspection interval

Question 2

What is the allowable maximum undercut depth in a shell vertical seam weld per API 650 acceptance criteria?

Accepted Answer

1/32 inch (0.8 mm)

Answer

1/64 inch (0.4 mm)

Answer

1/16 inch (1.6 mm)

Answer

3/32 inch (2.4 mm)

Question 3

Which document formally authorizes a welder to perform production welding on an API 653 repair project?

Accepted Answer

A welder performance qualification record (WPQ/WPQR) per ASME Section IX

Answer

The welder's union card or trade certification

Answer

The project manager's written approval

Answer

An API 653 inspector certification

Question 4

During visual inspection of a completed tank floor weld, an inspector finds a 2-inch length of weld that was skipped. What action is required?

Accepted Answer

Require the gap to be filled by welding to complete the continuous weld

Answer

Accept the gap if it is not in a high-stress area

Answer

Document it as an observation for the next inspection

Answer

Apply a corrosion-inhibiting patch over the unwelded area

Question 5

What is 'stress corrosion cracking' (SCC) in the context of welded tank components, and which zone is typically most susceptible?

Accepted Answer

Cracking caused by combined tensile stress and corrosive environment; most common in the HAZ

Answer

Uniform corrosion of the weld face; most severe in the weld cap

Answer

Erosion of the weld root due to fluid velocity; worst in inlet nozzles

Answer

Galvanic attack between weld metal and base metal; limited to the fusion line

Question 6

When a welded repair to a tank nozzle requires removal of an existing weld, which method is PREFERRED by API 653 to avoid damaging the base metal?

Accepted Answer

Air carbon arc gouging followed by grinding to clean metal

Answer

Grinding only using angle grinders

Answer

Flame cutting with an oxyfuel torch

Answer

Chipping hammers for mechanical removal

Question 7

Per API 653, what is the minimum overlap required when installing a lap-welded patch plate on a tank shell?

Accepted Answer

2 inches (51 mm)

Answer

1 inch (25 mm)

Answer

3 inches (76 mm)

Answer

4 inches (102 mm)