Pipe Testing and Inspection Flashcards

What is the primary hazard that makes pneumatic pressure testing more dangerous than hydrostatic testing?

Answer: Greater stored energy in compressed gas that can cause explosive failure

Compressed gas stores significantly more potential energy than liquid at the same pressure; a failure during pneumatic testing can release this energy explosively.

What does the acronym NDE stand for in piping inspection?

Answer: Non-Destructive Examination

Non-Destructive Examination (NDE) refers to inspection techniques that evaluate the integrity of materials or components without causing damage or rendering them unfit for service.

Which ASME code specifically governs the design, fabrication, inspection, and testing of process piping systems in refineries and chemical plants?

Answer: ASME B31.3 (Process Piping)

ASME B31.3, the Process Piping code, covers all requirements for piping typically found in petroleum refineries, chemical plants, and similar process facilities.

What is the key difference between a strength test and a leak test in piping systems?

Answer: Strength tests verify the system can withstand design pressure without failure; leak tests verify joints are properly sealed

A strength test (typically hydrostatic) confirms the piping system can safely withstand its required pressure, while a leak test specifically checks that all joints, connections, and seals are tight.

Which in-service inspection method uses a magnetic field to detect pipe wall loss and corrosion without removing insulation or coatings?

Answer: Magnetic flux leakage (MFL)

Magnetic flux leakage saturates the pipe wall with a magnetic field; areas of wall loss or corrosion disrupt the field, allowing detection through non-metallic coatings and insulation.

Under ASME B31.3, what minimum metal temperature margin above the minimum design metal temperature (MDMT) must be maintained during hydrostatic testing?

Answer: 10°F (6°C) above the MDMT

ASME B31.3 requires the metal temperature during hydrostatic testing to be at least 10°F (6°C) above the MDMT to prevent brittle fracture of the pipe material.

Which NDE method uses electromagnetic induction to detect surface and near-surface defects and is particularly suitable for non-ferromagnetic materials such as aluminum and austenitic stainless steel?

Answer: Eddy current testing (ET)

Eddy current testing induces electrical currents in the material; disruptions from defects alter the eddy current pattern and are detected by the probe, making it ideal for non-magnetic materials where MT cannot be used.