CWB Welding Inspector Level 2 cheat sheet

Arc voltage controls arc length: raising voltage lengthens the arc and widens the bead; raising current increases penetration and deposition rate.

Heat input (kJ/mm) = voltage × current × 60 / (travel speed in mm/min × 1000); arc efficiency is roughly 0.8 for SMAW and GMAW, about 1.0 for SAW.

Carbon equivalent (IIW) = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15; values above about 0.40 raise cold-cracking risk and call for preheat or hydrogen control.

SMAW electrodes: E7018 is low-hydrogen, all-position, DCEP only; E6010 is cellulosic, deep-penetrating, usable on DC only; E7024 is high-deposition, flat position only.

GMAW transfer modes: short-circuit (low current, thin plate), globular (medium), spray (above transition current, argon-rich gas, DCEP); pulsed spray stabilises spray at lower average current.

GTAW uses a non-consumable tungsten electrode with separate filler; DCEN concentrates heat in the work for steel, DCEP is avoided on thick work because it overheats the electrode.

SAW uses granular flux and bare wire at high current (up to ~1000 A) with high deposition, but is limited to flat or horizontal positions and needs flux handling.

FCAW self-shielded wires rely on core ingredients for shielding and tolerate wind; gas-shielded FCAW gives smoother beads and lower fume but needs shielding gas.

CSA W47.1 covers certification of welding companies and W47.2 covers aluminium; CSA W59 governs steel welded construction and pairs with W47.1 certification.

AWS D1.1 governs structural steel welding; it classifies steels by matching filler strength groups and defines prequalified joint details.

ASME BPVC Section IX governs procedure and performance qualification; Section V covers NDE methods; Section VIII covers pressure vessels.

API 1104 covers pipeline welding; acceptance is based on radiographic or other NDE evaluation of girth welds.

A specification states requirements (what), a code is a body of rules adopted into law or contract (mandatory), and a standard is a consensus document (may be referenced by code).

Code acceptance limits often differ from workmanship limits: D1.1 has static and cyclic (CVN-toughness) applications with different undersized/porosity allowances.

Essential variables are those whose change requires requalification; non-essential variables must be recorded in the WPS but may be changed without requalification.

Referenced documents in a code become mandatory to the extent cited; edition/year of the code governs unless the contract names another edition.

The reference line is horizontal; the arrow line meets it at one end; the tail (if used) carries process/spec references.

The arrow side is the side the arrow touches; the other side is the other side. Groove symbols sit on the arrow side of the reference line for arrow-side welds and on the other side for other-side welds.

Fillet weld: triangle symbol with leg size to the left of the symbol; length and pitch follow to the right (e.g., 6-50 means 6 mm leg, 50 mm length).

Supplementary symbols: concave (moon), convex, flush (straight line), and the all-around circle at the reference-line/arrow junction.

A WPS is a written qualified procedure; a PQR is the record of the test that qualified it; a WPQ (welder performance qualification) records the individual welder's test.

A welding symbol may have multiple reference lines (multi-pass/sequence) with the sequence number above or below each line.

Dimension units: drawings must state mm or inches; mixed-unit drawings use dual dimensions with one in parentheses.

Typical documentation set: drawing, WPS, PQR, welder qualification records, inspection reports, NDE reports, and material test certificates (MTRs).

Visual inspection (VT) is the primary method: it verifies fit-up, bead profile, spatter, undercut, and dimensional conformance before and after welding.

Penetrant testing (PT) detects surface-breaking discontinuities in non-porous materials; it is not suitable for rough or porous surfaces.

Magnetic particle testing (MT) detects surface and near-surface discontinuities in ferromagnetic materials only; it cannot inspect austenitic stainless or aluminium.

Ultrasonic testing (UT) uses high-frequency sound (typically 1-10 MHz) and detects internal planar defects well; it requires trained operators and reference blocks.

Radiographic testing (RT) detects volumetric internal defects; planar defects oriented parallel to the beam may be missed; it requires radiation safety controls.

Acceptance criteria for RT/UT are density/amplitude based: porosity is judged by size and distribution, while cracks and lack of fusion are generally rejectable regardless of size.

Leak testing (LT) methods include bubble, pressure-change, and tracer-gas techniques; they detect through-wall defects only.

Inspection points are commonly hold points (work cannot proceed without inspection), witness points (inspection may be waived if not attended), and review points (records only).

The heat-affected zone (HAZ) is the base metal not melted but thermally altered; it is often the weakest region because of grain growth or hardening.

Hydrogen-induced cold cracking occurs below about 200 °C, typically hours after welding; prevention uses low-hydrogen consumables, preheat, and controlled cooling.

Preheat slows cooling, lowers hardness in the HAZ, and helps hydrogen escape; interpass temperature limits prevent loss of toughness in some steels.

Austenitic stainless steels are susceptible to sensitisation (chromium carbide precipitation at grain boundaries) between roughly 425 and 870 °C, causing intergranular corrosion.

Ferrite content in austenitic stainless welds is controlled (often 3-10 FN) to resist solidification cracking while limiting sigma-phase formation.

Aluminium forms a tenacious oxide film (melting near 2050 °C vs. aluminium near 660 °C) that must be removed mechanically or by AC cleaning action in GTAW.

Carbon steel strength and hardenability increase with carbon and alloy content; CE calculation predicts hardenability and cracking risk.

Post-weld heat treatment (PWHT) relieves residual stress and tempers hard microstructures; it must be applied within a controlled temperature range to avoid degrading properties.

A WPS is qualified by a PQR; the PQR records essential variables, test results, and mechanical test outcomes that demonstrate the procedure produces acceptable properties.

Welder performance qualification (WPQ) tests the individual's ability; it is separate from procedure qualification and must be renewed after defined periods or after a change in process.

Essential variables for procedure qualification typically include process, base metal group, filler classification, thickness range, position, preheat, and PWHT.

Thickness qualification ranges: a test coupon qualifies a range; for example, a 10 mm coupon in many codes qualifies roughly 5-20 mm (verify against the governing code).

A welder qualified in a given position and thickness range may weld only within that range; position qualification is often expressed as 1G/2G/3G/4G for plate and 1G-6G for pipe.

Quality control records include material traceability, consumable control (storage and baking of low-hydrogen electrodes), and calibration records for inspection equipment.

Nonconformance handling uses a defined path: identify, document, disposition (rework, repair, or scrap), re-inspect, and close out.

Audit and surveillance verify that the approved WPS is being followed; deviation from the WPS is a nonconformance regardless of weld appearance.