Welding Contractors Industry Terminology

Air Carbon Arc Gouging (CAC-A)

Process that removes metal using a carbon electrode and compressed air; commonly used for back-gouging roots or removing defects. Requires high current, proper polarity, and robust PPE for arc flash, noise, and fume.

'Back-gouge the root with CAC-A before the repair weld'; 'Set CAC-A to DCEP per the electrode manufacturer'; 'Confirm air pressure and electrode size match the WPS'.

Amperage

The welding current (A) that largely controls penetration and deposition rate along with voltage and travel speed. Too low can cause lack of fusion; too high can cause burn-through or excessive spatter.

'Increase amperage 10 A for better toe fusion'; 'Your amps are too high for that root opening'; 'Log actual amps for heat input calculation'.

API 1104

American Petroleum Institute code for Welding of Pipelines and Related Facilities. Governs WPS/WPQ qualification and acceptance criteria for pipeline work.

'Qualify the procedure per API 1104 for the gas tie-in'; 'RT acceptance is per API 1104, Section 6'; 'Use 6010/7010 progression per API 1104 allowances'.

ASME Section IX

Boiler and Pressure Vessel Code section governing qualification of welding/brazing procedures (WPS/PQR) and personnel (WPQ). Industry standard for pressure-retaining items.

'Run a PQR per ASME IX with impact tests'; 'Welder 123 is qualified 6G per Section IX'; 'Essential variables changed—requalify per IX'.

AWS D1.1

American Welding Society Structural Welding Code—Steel. Covers design, qualification, fabrication, and inspection for structural steel.

'Use a prequalified WPS per AWS D1.1 Clause 5'; 'Visual acceptance is per D1.1 Table 6.1'; 'WPS range must meet D1.1 Clause 4'.

Backing Bar/Ring

Material placed behind the joint root to support molten weld metal (steel bar, ceramic, copper, or ring for pipe). May be removable or left in place depending on code/project.

'Use ceramic backing for one-sided fillets'; 'Remove steel backing and back-gouge before the final pass'; 'D1.1 prohibits permanent backing in this detail'.

Base Metal

The parent metal being welded, often grouped by P-Number (ASME) or Group Number (AWS). Properties and chemistry influence preheat, filler selection, and PWHT.

'This is P-No. 1 carbon steel'; 'High-strength base metal requires low-hydrogen practice'; 'Match filler to the base metal’s tensile strength'.

Bevel Angle

The angle of the joint preparation for groove welds, impacting penetration, access, and heat input. Too small can cause lack of fusion; too large raises weld volume and cost.

'Set a 37.5° included angle'; 'Bevel per WPS to reduce excessive fill passes'; 'Incorrect bevel caused LOF on UT'.

Bill of Materials (BOM)

Comprehensive list of materials and components required for fabrication/installation. Drives purchasing, kitting, and cost control.

'Update the BOM after the revision'; 'Shortages traced to an inaccurate BOM'; 'ERP imports the BOM from the shop drawings'.

Certified Welding Inspector (CWI)

AWS credential that validates an individual’s competence in welding inspection. CWIs oversee WPS compliance, fit-up, and acceptance criteria.

'Have the CWI sign off the ITP hold point'; 'The CWI rejected the fillet for undercut'; 'CWI verified the welder’s continuity'.

Change Order

A formal modification to the contract scope, time, or price. Requires documented cause, pricing, and approval.

'Submit a CO for added 6G welds'; 'Owner approved the CO after RFI response'; 'Track COs to protect margin'.

DCEP/DCEN (Polarity)

Direct Current Electrode Positive (DCEP) vs Electrode Negative (DCEN). Affects penetration, bead profile, and electrode usability.

'Run E7018 on DCEP'; 'Switch to DCEN for CAC-A per spec'; 'Wrong polarity caused arc instability'.

Distortion Control

Techniques to minimize weld shrinkage and bending, such as balanced welding, back-step sequence, clamps/fixtures, and heat input control.

'Use a staggered sequence on the long seam'; 'Tack more frequently to hold alignment'; 'Reduce heat input to limit camber'.

Electrode/Filler Metal Classification (E7018, ER70S-6)

Standardized nomenclature that indicates strength, usability, composition, and position (e.g., E7018, ER70S-6, E71T-1). Drives matching of filler to base metal and service.

'Use ER70S-6 for GMAW on A36'; 'Low-hydrogen E7018 for critical joints'; 'Switch to E71T-8 for windy field conditions'.

FCAW (Flux-Cored Arc Welding)

Wire-fed process with a flux core; can be self-shielded (FCAW-S) or gas-shielded (FCAW-G). High deposition and good outdoors performance.

'Use FCAW-S for the structural erection'; 'Specify 75/25 gas for FCAW-G'; 'Adjust parameters to prevent worm tracks'.

Fillet Weld

A triangular weld joining two surfaces at approximately right angles. Size is typically the leg length; throat governs strength.

'Detail shows 6 mm fillet both sides'; 'Unequal leg fillet per symbol'; 'Measure effective throat for design check'.

Fit-Up

The alignment, gap, and bevel of parts before welding; critical to quality and productivity. Uses clamps, strong-backs, and wedges to achieve tolerance.

'Gap is 1/8 inch per WPS'; 'Poor fit-up drove excessive weld volume'; 'CWI rejected fit-up for hi-lo'.

GMAW (MIG)

Gas Metal Arc Welding; wire-fed with shielding gas. Modes include short-circuit, globular, spray, and pulsed spray.

'Switch to spray transfer for thicker plate'; 'Short-arc is spattering—check parameters'; 'Use 90/10 Ar/CO2 for pulsed GMAW'.

GTAW (TIG)

Gas Tungsten Arc Welding; uses a non-consumable tungsten electrode and separate filler. Offers high-quality, precise welds; sensitive to cleanliness.

'Purge the stainless root for GTAW'; 'Use 2% thoriated or ceriated tungsten'; 'Torch angle is causing lack of shielding'.

Groove Weld

A weld in a groove between members (butt joints), such as V, U, J, or square groove. Root opening, land, and bevel control fusion and volume.

'Single-V groove with 60° included angle'; 'Back-gouge and weld the second side'; 'Full-pen groove per detail 5/S3'.

HAZ (Heat-Affected Zone)

The portion of base metal not melted but whose microstructure/properties changed by welding. Size and hardness depend on heat input and material chemistry.

'Hard HAZ caused hydrogen cracking'; 'Reduce heat input to limit HAZ width'; 'Measure HAZ hardness per ITP'.

Hot Work Permit

Authorization required for welding, cutting, or grinding in areas with fire/explosion risk. Specifies precautions like fire watch, gas testing, and isolations.

'Obtain a hot work permit before welding on the mezzanine'; 'Fire watch for 60 minutes after completion'; 'No hot work until LEL is zero'.

Hydrogen-Assisted Cracking (HAC)

Delayed cracking mechanism driven by diffusible hydrogen, stress, and susceptible microstructure. Mitigated by low-hydrogen consumables, preheat/interpass control, and PWHT when required.

'Bake E7018 to reduce hydrogen'; 'Increase preheat to 200°C to mitigate HAC'; 'HIC observed 24 hours after welding'.

Inspection and Test Plan (ITP)

Document that sequences inspections, tests, and hold/witness points by activity. Aligns code, client, and contractor expectations.

'Add a hold point for fit-up'; 'CWI and owner to witness the leak test'; 'ITP references D1.1 visual acceptance'.

Interpass Temperature

The temperature of the weld area between passes; limits grain growth and affects hydrogen control. Managed with thermometers/pyrometers per WPS.

'Keep interpass below 300°F'; 'Record interpass on the weld map'; 'Interpass exceeded—NCR required'.

Joint Design

Specification of groove/fillet geometry including bevel angle, root face, and opening. Impacts access, distortion, and weld volume.

'Use a J-groove to reduce volume'; 'Root face 1.6 mm per drawing'; 'Joint design per AWS D1.1 Fig 3.3'.

JSA/JHA (Job Safety Analysis)

Structured review of job steps to identify hazards and define controls. Often required daily before welding tasks.

'Complete the JSA before hot work'; 'Add controls for fume extraction'; 'Supervisor reviewed and signed the JHA'.

Lack of Fusion

Discontinuity where weld metal fails to fuse to base metal or previous welds. Typically caused by low heat input, poor technique, or incorrect angles.

'UT flagged LOF at the toe'; 'Increase voltage and reduce travel speed'; 'Grind out LOF and re-weld per repair WPS'.

Lockout/Tagout (LOTO)

Safety process for isolating energy sources before work. Includes lock, tag, verification, and zero-energy confirmation.

'LOTO the pump before tie-in welding'; 'Perform try-start to verify isolation'; 'Remove locks only after sign-off'.

Magnetic Particle Testing (MT)

NDE method for detecting surface and near-surface flaws in ferromagnetic materials using magnetic fields and iron particles.

'Perform yoke MT after the root pass'; 'Indications verified as relevant cracks'; 'Demagnetize after MT to avoid debris'.

Mill Test Report (MTR) and Heat Number

Manufacturer’s certificate listing chemical and mechanical properties of a heat of steel. Heat numbers on parts enable traceability to the MTR.

'Verify the heat stamp matches the MTR'; 'Record MTRs in the turnover package'; 'Material fails spec—quarantine that heat'.

NCR (Nonconformance Report)

Formal record of work or material not meeting requirements, with disposition (use-as-is, repair, rework, scrap). Drives corrective actions.

'Issue an NCR for interpass exceedance'; 'Repair per approved WPS and close NCR'; 'Trend NCRs to target training'.

NDE/NDT (Nondestructive Examination)

Umbrella term for inspection methods that don’t damage the part (VT, PT, MT, UT, RT, PAUT). Acceptance criteria come from codes/specs.

'Select UT instead of RT for schedule'; 'NDE per ITP and client spec'; 'Record NDT reports in turnover'.

PQR (Procedure Qualification Record)

Test record proving a WPS can produce acceptable welds under specified variables. Includes test coupon results (tension, bend, impact, hardness).

'Run a new PQR for 9% Ni plate'; 'Change in essential variable requires PQR requalification'; 'Attach PQRs to the WPS package'.

PPE (Personal Protective Equipment)

Equipment to protect workers: auto-darkening hoods, FR clothing, gloves, safety glasses, respirators, hearing protection.

'Use P100 when welding galvanized'; 'FR sleeves required for overhead work'; 'Helmet shade 10–12 for arc brightness'.

Preheat Temperature

Minimum base-metal temperature before welding to reduce cooling rate and hydrogen cracking risk. Determined by code, thickness, and chemistry.

'Preheat to 150°C for this P-No. 5 steel'; 'Use temp sticks to verify preheat'; 'Preheat maintained between passes'.

PWHT (Post Weld Heat Treatment)

Controlled heating after welding to reduce residual stress, temper the HAZ, or meet toughness requirements. Strictly specified by code/material.

'PWHT at 620°C for 2 hours'; 'Attach PWHT charts to the dossier'; 'Local PWHT with ceramic pads approved'.

QA/QC (Quality Assurance/Quality Control)

QA is the system and planning; QC is the execution and verification. Together they ensure compliance and continuous improvement.

'QA developed the welding quality plan'; 'QC inspected fit-up and root pass'; 'Audit found gaps in filler control'.

Radiographic Testing (RT)

Volumetric NDE using X-rays or gamma rays to detect internal flaws (porosity, slag, LOF). Film or digital.

'RT 10% of production welds'; 'Interpret per code acceptance'; 'Switch to UT where access is limited'.

RFI (Request for Information)

Formal question to clarify drawings/specs; used to avoid assumptions and document decisions.

'Issue an RFI for the missing weld detail'; 'RFI #27 changed the joint design'; 'CO stemmed from RFI response'.

Root Pass

The first weld pass that establishes penetration and root fusion. Often requires controlled heat and technique to avoid burn-through.

'Feather the tacks before the root'; 'Keyhole technique for open-root SMAW'; 'RT failed due to lack of root fusion'.

SAW (Submerged Arc Welding)

High-productivity process where the arc is submerged under granular flux. Excellent for thick sections, long seams, and shop fabrication.

'Run SAW on the tank seam'; 'Flux recycling procedure required'; 'Parameter window per WPS for SAW tandem'.

SMAW (Shielded Metal Arc Welding)

Manual 'stick' welding using flux-coated electrodes. Versatile, portable, and tolerant of wind/dirty conditions.

'7018 for structural fillets'; '6010 open-root then 7018 fill/cap'; 'Keep rods in the oven at 250°F'.

Ultrasonic Testing (UT)

Volumetric NDE using high-frequency sound to detect and size internal flaws. Techniques include straight-beam and angle-beam; PAUT is an advanced variant.

'Angle-beam UT 60° for weld volume'; 'Calibrate on a V1 block'; 'UT found lack of sidewall fusion'.

Visual Testing (VT)

Primary NDE method; checks weld size, profile, cleanliness, and defects using gauges and lights. Most cost-effective and first line of quality.

'VT acceptance per AWS D1.1 Table 6.1'; 'Measure fillet leg with a gauge'; 'VT prior to RT saved rework'.

Voltage

Electrical potential (V) across the arc; influences arc length, bead width, and spatter. Works with amperage and travel speed to set heat input.

'Lower voltage to tighten the arc'; 'Voltage drift—check the power source'; 'Log volts for procedure compliance'.

WPS (Welding Procedure Specification)

Authorized document specifying essential and supplementary variables (process, base/filler, preheat, PWHT, parameters). Demonstrated by a PQR unless prequalified.

'Follow the WPS for parameter range'; 'Client approved the WPS package'; 'Change in position is outside WPS—stop work'.

WPQ (Welder Performance Qualification)

Record showing a welder’s qualification test results and limits (process, position, thickness, diameter). Requires continuity to remain active.

'Welder 45 is qualified 6G to 24-inch'; 'Continuity log shows no lapse'; 'Requalify after essential variable change'.

Weld Symbols

Standardized graphical language on drawings (reference line, arrow, symbol, tail) per AWS A2.4/ISO 2553. Communicates type, size, length, and contour.

'Field weld symbol at the arrow'; 'All-around symbol on the perimeter'; '6 mm fillet both sides per symbol'.

Yield Strength

Stress at which material begins to plastically deform; critical for design, WPS selection, and matching filler strength.

'Use 80 ksi filler for high-yield pipe'; 'Heat input controlled to protect HAZ in 690 MPa steel'; 'Confirm yield on the MTR before welding'.