API RP 577 - Answers Provides guidance on welding inspection for refinery and chemical plant
equipment and piping.
Four main areas - Answers 1. Common welding processes, 2. Welding procedures, 3. Welder
qualifications, 4. Metallurgical effects.
Factors for welding process - Answers Material thickness, joint configuration, access, code
requirements, and welder qualifications.
SMAW & GTAW - Answers Shielded Metal Arc Welding (SMAW) and Gas Tungsten Arc Welding
(GTAW) used in pressure vessel construction.
Difference SMAW & GTAW - Answers SMAW uses consumable electrode, while GTAW uses non
-consumable tungsten electrode and separate filler metal.
Submerged arc welding (SAW) - Answers Advantage: Higher deposition rate and improved weld
quality due to protection from the atmosphere by a flux covering.
Welding Procedure Specification (WPS) - Answers Defines essential welding variables for
specific applications to ensure repeatability by qualified welders.
Information in a WPS - Answers Base metal and filler metal specs, welding process, joint details,
preheat and post-heat treatment requirements, welding parameters.
Welder qualification testing - Answers Demonstrates a welder's ability to produce welds
meeting required quality standards for specific procedures and materials.
Types of welder qualification tests - Answers 1. Bend test: Evaluates ductility and soundness of
the weld metal. 2. Macro and/or micro examination: Analyzes the weld microstructure for
potential defects.
Welder qualification validity - Answers Six months for manual welding, one year for
automatic/semi-automatic processes, with specific conditions for maintaining validity.
Heat-affected zone (HAZ) - Answers Region around the weld metal experiencing temperature
change during welding, leading to microstructural and mechanical property changes.
Excessive grain growth in HAZ - Answers Results in reduced toughness and increased
susceptibility to cracking.
Preheating and post-heat treatment - Answers Mitigate negative welding effects by controlling
cooling rate and reducing undesirable microstructures in the HAZ.
Primary shielding gas in GMAW - Answers Inert gases like argon or mixtures with CO2 for
specific applications.
, Difference FCAW & solid wire GMAW - Answers FCAW uses self-shielded flux-cored wire,
eliminating the need for separate shielding gas; solid wire GMAW requires external shielding
gas.
Advantages of pipe welding processes - Answers Improved consistency, reduced operator
dependence, and potential for higher welding speeds and productivity.
Essential vs. non-essential variables in a WPS - Answers Essential variables significantly impact
weld quality and require strict adherence, while non-essential variables can be adjusted within a
specified range.
Procedure Qualification Record (PQR) - Answers Demonstrates successful qualification of a
WPS through testing and evaluation of welds produced according to that procedure.
Documentation for welding procedures - Answers Copies of WPSs, PQRs, and welder
qualification records, readily accessible for inspection and reference.
Factors affecting welder qualification validity - Answers Lapse in time, change in welding
process or material, or failure to meet specific renewal requirements.
Inspector verification of welder's qualification - Answers Reviewing the welder qualification
record to ensure it covers relevant welding process, material, and position for the intended work.
Grain refinement vs. coarsening in HAZ - Answers Refinement improves toughness, while
coarsening reduces toughness in the heat-affected zone.
Mitigation of hydrogen-induced cracking (HIC) - Answers Preheating and post-heat treatment
reduce hydrogen diffusion into the metal, mitigating HIC formation.
Visual inspection techniques - Answers Direct visual inspection, use of mirrors, and
magnification tools for weld evaluation.
Liquid penetrant testing (PT) - Answers Detects surface-breaking cracks or discontinuities using
a penetrating liquid revealed under ultraviolet light.
Safety precautions for magnetic particle testing (MT) - Answers Proper grounding, appropriate
PPE, and avoiding testing near flammable materials due to strong magnetic fields.
Radiographic testing (RT) - Answers Passing X-rays or gamma rays through the weld to detect
internal defects
Acceptance criteria - Answers Specific limits to define acceptable/unacceptable weld defects
based on size, location, and impact
Welding Procedure Qualification Record (PQR) - Answers Demonstrates successful qualification
of WPS through testing and evaluation