API 510 Repair, Alteration & Rerating Procedures 5

Question 1

API 510 states that the inspector should review which documents before approving a repair involving welding?

Accepted Answer

Welding procedure specifications (WPS), welder qualifications, and the repair plan

Answer

Only the repair contractor's insurance certificate

Answer

The vessel's original purchase order only

Answer

The plant safety manual and emergency response plan

Question 2

A steel pressure vessel shell has corroded to a thickness below the minimum required. The owner plans to restore it by welding a full encirclement sleeve. This is considered a:

Accepted Answer

Permanent repair if designed and executed to applicable code requirements

Answer

Minor maintenance activity

Answer

Temporary repair only, valid for one inspection interval

Answer

Cosmetic enhancement not subject to inspection

Question 3

Under API 510, when does a change in service fluid (e.g., from water to a lethal gas) require the vessel to be treated as an alteration?

Accepted Answer

When the new service results in more severe conditions not covered by the original design or code requirements

Answer

Any change in service fluid is automatically an alteration

Answer

Only when the new fluid is corrosive

Answer

Only when the operating temperature changes by more than 50°F

Question 4

After completing an alteration, the 'R' stamp holder must update the nameplate to show:

Accepted Answer

The new MAWP, temperature, and the 'R' stamp number with the alteration year

Answer

The repair contractor's name and address

Answer

Only the alteration date

Answer

The name of the authorized inspector only

Question 5

When calculating the MAWP for rerating a vessel shell, the inspector uses the 'actual measured thickness' rather than the nominal thickness because:

Accepted Answer

Nominal thickness always overstates the actual metal available after corrosion and mill tolerance

Answer

Regulations prohibit the use of nominal thickness in any calculation

Answer

Actual thickness is always thicker than nominal due to manufacturing tolerances

Answer

ASME code requires only nominal thickness for new construction, not repairs

Question 6

API 510 requires that any hot-tap performed on an in-service pressure vessel be:

Accepted Answer

Evaluated and approved by the authorized inspector and supported by engineering analysis

Answer

Restricted to vessels with MAWP below 150 psi

Answer

Performed only when the vessel is fully depressurized

Answer

Prohibited on all pressure vessels without exception

Question 7

A vessel was originally built with a joint efficiency (E) of 0.70 (spot radiographed). If during rerating the inspector upgrades the joint efficiency to 1.0 by performing full radiography of all welds, the MAWP will:

Accepted Answer

Increase because the allowable stress is effectively higher at E=1.0

Answer

Remain unchanged because joint efficiency does not affect MAWP

Answer

Decrease because more scrutiny reveals more defects

Answer

Double because joint efficiency is a multiplier applied to the safety factor