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

Cracking along the weld centerline due to hot cracking

Answer

Surface cracking caused by hydrogen embrittlement in the HAZ

Answer

Cracking due to excessive weld reinforcement grinding

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

5%

Answer

25%

Answer

50%

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

Cracking on the surface of the weld crown

Answer

Incomplete fusion at the root of the weld joint

Answer

Thermal fatigue cracking in the weld toe area

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

Insufficient preheat temperature before welding

Answer

Incorrect shielding gas mixture

Answer

Inadequate post-weld heat treatment

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

The color-coding scheme used on the drawing

Answer

The signature of the project engineer approving the design

Answer

The cost estimate for each weld repair item

Question 6

What is the significance of the 'essential variable' concept in ASME Section IX welding qualification?

Accepted Answer

Variables whose change requires requalification of the weld procedure

Answer

Variables that must be recorded but do not require requalification if changed

Answer

Variables that only apply to pressure vessel welding, not storage tanks

Answer

Variables that determine the color code on the weld map

Question 7

A weld repair on a tank shell in hydrogen service requires special consideration for which weld discontinuity?

Accepted Answer

Hydrogen-induced cracking (HIC) in the HAZ

Answer

Surface porosity

Answer

Lack of fill on the weld crown

Answer

Excess weld reinforcement