NDT Boilermaker Structural Integrity Assessments 5

Question 1

Which factor MOST significantly influences the minimum required thickness calculation for a cylindrical boiler shell under internal pressure?

Accepted Answer

Inside radius, allowable stress, and joint efficiency

Answer

The hoop stress formula t = PR/(SE) shows that inside radius (P), allowable stress (S), and joint efficiency (E) directly determine required wall thickness.

Question 2

When using eddy current testing to inspect non-ferromagnetic boiler tubes, a phase angle shift of approximately 90° between two indications MOST likely distinguishes:

Accepted Answer

Inside diameter (ID) defects from outside diameter (OD) defects

Answer

In eddy current tube inspection, the phase angle of the signal response indicates the depth location of the discontinuity, with ID and OD defects typically separated by approximately 90° on the impedance plane.

Question 3

A fitness-for-service assessment per API 579-1/ASME FFS-1 for a pressure vessel with general metal loss typically uses which Level 1 screening criterion?

Accepted Answer

Remaining thickness ratio (RTR) compared to a minimum allowable ratio

Answer

API 579 Level 1 FFS assessment for general metal loss uses the remaining thickness ratio (RTR = measured thickness / required thickness) compared to a minimum acceptable ratio.

Question 4

During a boiler inspection, an inspector identifies hydrogen damage characterized by internal fissures and blistering in the tube wall. What operating condition MOST likely caused this damage?

Accepted Answer

Hydrogen sulfide attack at high temperature (high-temperature hydrogen attack)

Answer

High-temperature hydrogen attack (HTHA) occurs when atomic hydrogen at elevated temperatures reacts with carbides in steel, forming methane bubbles that cause internal fissuring and decarburization.

Question 5

In the context of boiler structural integrity, what does 'minimum design metal temperature' (MDMT) define?

Accepted Answer

The lowest temperature at which the component can be pressurized without risk of brittle fracture

Answer

MDMT is the lowest permissible temperature at which a pressure component may be subjected to full design pressure, below which brittle fracture risk becomes unacceptable.

(NDT) Boilermaker Nondestructive Testing Certification Practice Test

(NDT) Boilermaker Nondestructive Testing Certification Practice Test

NDT Boilermaker Structural Integrity Assessments 5