API 653 Welding Inspection 4

Question 1

What is 'lamellar tearing' and under what conditions is it most likely to occur in tank construction?

Accepted Answer

Subsurface cracking in base metal parallel to the plate surface under through-thickness stress

Answer

Lamellar tearing occurs in the base metal beneath welds when through-thickness stresses act on inclusion-rich steel with low ductility in the Z-direction.

Question 2

When API 653 requires radiography of a repaired weld, what percentage of the completed weld length must be radiographed as a minimum for spot examination?

Accepted Answer

10%

Answer

Spot radiography per API 650/653 requires a minimum of 10% of each welder's completed weld length to be examined radiographically.

Question 3

Which of the following best describes 'underbead cracking' in a welded joint?

Accepted Answer

Hydrogen-induced cracking in the heat-affected zone below the weld

Answer

Underbead cracking is hydrogen-induced cracking that occurs in the HAZ just below the weld deposit, typically in high-carbon or alloy steels.

Question 4

An inspector notices that a vertical weld on a tank shell exhibits consistent undercut along both toes of the weld. What is the most likely root cause?

Accepted Answer

Excessive welding current or travel speed

Answer

Undercut is most commonly caused by excessive welding current or travel speed, which melts the base metal at the weld toes faster than it can be filled.

Question 5

When reviewing a weld map for a major shell repair, what information is MOST critical for the inspector to verify?

Accepted Answer

That each weld is identified, the procedure and welder assigned, and NDE requirements noted

Answer

A weld map must identify each weld joint with its applicable WPS, assigned qualified welder, and required NDE to ensure all work is traceable and meets specifications.

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

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

API 653 Welding Inspection 4