Quality Control and Materials Flashcards

What is the purpose of a 'witness point' in an inspection and test plan, and how does it differ from a 'hold point'?

Answer: A witness point allows work to proceed if the inspector does not attend after notification, while a hold point requires presence before work continues

At a witness point, the contractor notifies the inspector and may proceed if the inspector does not show; a hold point mandates the inspector's physical presence before work can advance.

In ultrasonic thickness measurement (UTM) of corroded piping, what is the term for the minimum thickness value below which the component must be repaired or replaced?

Answer: Required minimum thickness (t_min)

The required minimum thickness (t_min) is the calculated value based on pressure, temperature, and applicable code; readings below this value require repair or replacement.

According to API 570, who is qualified to authorize repairs and alterations on in-service piping systems?

Answer: An API 570 Authorized Piping Inspector in conjunction with an engineer

API 570 requires repairs and alterations to be authorized by a certified API 570 Inspector working in conjunction with a qualified engineer.

What is 'corrosion under insulation' (CUI) and why is it a significant QC concern in petroleum facilities?

Answer: Corrosion occurring beneath insulation, often undetected until significant damage has occurred

CUI occurs when moisture penetrates insulation and promotes corrosion on the pipe or vessel surface where it cannot be visually detected without removing insulation.

In the context of API quality audits, what is a 'corrective action request' (CAR)?

Answer: A formal document requiring the auditee to investigate a nonconformance and implement actions to prevent recurrence

A CAR is issued when an audit finding reveals a nonconformance; it requires root cause analysis and corrective actions to prevent recurrence.

What is 'stress corrosion cracking' (SCC) and which combination of conditions is required for it to occur?

Answer: A combination of susceptible material, tensile stress, and a specific corrosive environment acting simultaneously

SCC requires three simultaneous conditions: a susceptible material, tensile stress (residual or applied), and a specific corrosive environment such as chlorides or caustic.

When API standards reference 'traceability' for pressure-containing components, what minimum information must be maintained?

Answer: Material grade, heat/lot number, applicable specification, and test certification linking each component to its MTR

Full traceability requires linking each component to its heat number, material specification, mechanical and chemical test data so any suspect material can be identified and removed.