Answers
maximum inspection interval - ✔✔10 years.
Corrosion Under Insulation (CUI) - ✔✔Localized external corrosion occurring under insulation
due to moisture ingress (API 570 Section 5.5.2).
hardness testing - ✔✔Required for P-No. 3 through P-No. 15 materials or when specified by the
inspector (API 570 Section 8.1.6.2).
minimum hold time - ✔✔10 minutes (Section 9.2.3).
documentation - ✔✔A detailed report including location, repair method, and deadline for
permanent repair (Section 8.1.5.2).
half-life rule - ✔✔If remaining life < 2x the inspection interval, inspect at half the remaining life
(Section 6.3.3).
thickness for a temporary repair clamp - ✔✔Must match or exceed the nominal pipe thickness
(Section 8.1.5.1).
qualifications for an API 570 inspector - ✔✔Valid API 570 certification, knowledge of ASME
B31.3, and experience with in-service piping (Section 4.2).
radiographic testing (RT) - ✔✔For all pressure-containing welds (Type A) unless replaced by UT
with inspector approval (Section 8.1.6.1).
, minimum number of TMLs - ✔✔At least 2 TMLs per circuit (Section 6.3.2).
acceptance criteria for pitting corrosion - ✔✔Pits must not reduce thickness below t_min, and
adjacent pits must not interact (Section 7.3.2).
purpose of a Piping Inspection Plan (PIP) - ✔✔To define inspection methods, intervals, TMLs,
and acceptance criteria (Section 5.2).
post-weld heat treatment (PWHT) - ✔✔When thickness ≥ 19 mm (0.75 in) for P-No. 1 materials
(ASME B31.3, referenced in API 570).
Risk-Based Inspection (RBI) - ✔✔A methodology to prioritize inspections based on risk
(probability × consequence) (Section 5.6).
maximum allowed weld reinforcement - ✔✔3 mm (1/8 in) for pipe ≤ 25 mm (1 in) thick; 5 mm
(3/16 in) for thicker pipe (ASME B31.3).
difference between Type A and Type B welds - ✔✔Type A: Pressure-containing welds (e.g.,
circumferential). Type B: Structural welds (e.g., supports) (Section 8.1.1).
thickness measurements after a piping alteration - ✔✔Before returning to service (Section
8.2.3).
minimum thickness for a pipe - ✔✔t_min = 0.30 - 0.10 = 0.20 in.
thickness measurements - ✔✔Before returning to service (Section 8.2.3).
minimum thickness - ✔✔t_{min} = 0.30 - 0.10 = 0.20 in.