API 577 flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Hold point
- A stage in fabrication where work must stop until the inspector has completed the required inspection and recorded acceptance; no further welding is permitted without sign-off.
- Witness point
- A fabrication stage where the inspector must be notified and may observe the activity, but work may continue if the inspector does not attend.
- Heat input formula
- Heat input in kJ/in equals arc voltage times amperage times 60, divided by travel speed in inches per minute times 1000.
- Carbon equivalent
- A calculated value combining carbon with other alloying elements to estimate hardenability and susceptibility to hydrogen cracking, used to set preheat requirements.
- Pre-weld inspection
- Verification before arc-on of base metal identity, joint fit-up and cleanliness, preheat, WPS availability, consumable condition, and welder qualification.
- Nonconformance report
- A document recording a deviation from specification, identifying the affected item, and tracking the engineering disposition and any corrective action taken.
- SMAW process
- Shielded metal arc welding uses a flux-coated consumable electrode; the flux creates shielding gas and a slag layer that must be removed between passes.
- GTAW process
- Gas tungsten arc welding uses a nonconsumable tungsten electrode and separately supplied filler; it produces high-purity welds and is often used for root passes.
- SAW process
- Submerged arc welding uses a continuous wire and a granular flux blanket; high deposition rates suit flat and horizontal positions because of the large pool.
- Essential variable
- A welding parameter that, if changed beyond the qualified range, requires requalification, such as base metal group, filler, position, preheat, or post-weld heat treatment.
- Procedure qualification record
- A record documenting the actual welding parameters used and the results of mechanical tests performed to qualify a welding procedure specification.
- Welder performance qualification
- A test demonstrating a welder's ability to produce sound welds; it is specific to process, position, and thickness ranges and must be renewed periodically.
- Hydrogen-induced cracking
- Cold cracking occurring after welding when hydrogen, a hard susceptible microstructure, and tensile stress combine; it is delayed and often appears hours later.
- Sensitization
- Chromium carbide precipitation at grain boundaries in austenitic stainless steels exposed to 800–1500°F, which depletes chromium and reduces corrosion resistance.
- Hot cracking
- Solidification cracking at high temperature in the weld metal, promoted by sulfur and phosphorus, deep weld pools, and high joint restraint.
- Lamellar tearing
- Step-like cracking beneath a weld in rolled plate, caused by nonmetallic inclusion stringers opening under through-thickness contraction strain.
- Reheat cracking
- Cracking during post-weld heat treatment of thick low-alloy sections, driven by stress relaxation in coarse-grained regions with low creep ductility.
- Duplex ferrite content
- Duplex stainless steel welds usually require 35 to 65 percent ferrite to balance strength and toughness while maintaining resistance to chloride stress corrosion cracking.
- Radiographic testing
- Radiation transmitted through a part is attenuated more by thicker or denser material; voids allow more radiation through and appear darker on the image.
- Ultrasonic testing
- High-frequency sound waves reflect from acoustic discontinuities; the method detects planar defects such as cracks and needs a smooth surface and couplant.
- Magnetic particle testing
- A magnetic field is applied to a ferromagnetic part, and surface or near-surface discontinuities distort the field and attract particles, forming a visible indication.
- Penetrant testing
- A liquid penetrant enters surface-breaking discontinuities and is drawn out by a developer; only nonporous materials can be examined and only surface defects are found.
- Visual examination
- The most basic examination method, performed before other techniques to confirm surface condition, cleanliness, fit-up, and the presence of gross defects.
- Preheat measurement
- Preheat should be verified with a contact pyrometer or thermocouple within a few inches of the joint, on the side opposite the heat source.
- Backstep welding technique
- Welding progresses in short segments opposite to the general direction of travel, distributing heat and reducing distortion and residual stress.
- Low-hydrogen electrode storage
- After opening, low-hydrogen electrodes are held in holding ovens at about 250 to 300 degrees F and baked per manufacturer instructions before use.
- Distortion control methods
- Balanced welding sequences, presetting, backstepping, minimum passes, and judicious restraint all limit shrinkage distortion in fabricated assemblies.
- Joint fit-up
- Alignment, root gap, bevel angle, and cleanliness established before welding; poor fit-up raises stress concentration and can cause incomplete penetration.
- Lack of fusion
- A discontinuity where weld metal fails to fuse to the base metal or to a previous pass; it is planar and is detected best by ultrasonic testing.
- Repair excavation
- Defective metal is removed by grinding or gouging until sound metal is reached, then verified by magnetic particle or penetrant testing before rewelding.
- Stress corrosion cracking
- Cracking caused by the combined action of tensile stress and a corrosive environment, common in austenitic stainless steels exposed to chlorides.
- Post-weld heat treatment
- Controlled heating of a completed weldment to relieve residual stress and temper hard microstructures; the hold temperature must remain above the tempering range.