Welding Fundamentals and AWS Terminology

In GTAW, the tungsten electrode is non-consumable — it creates the arc but is NOT intended to melt into the weld pool. Filler metal, when used, is added separately by manually feeding a filler rod (dabbing technique for manual GTAW). The tungsten electrode must be kept from contaminating the weld — touching the tungsten to the weld pool or filler rod is called "contaminating the tungsten," which introduces tungsten inclusions and requires the tungsten to be re-ground or replaced. GTAW can also be performed autogenously (without filler metal) on thin material by fusing the base metal edges together. This is in contrast to GMAW and SMAW, where the electrode IS the filler metal (consumable).

The AWS CWI (Certified Welding Inspector) credential, administered by the American Welding Society, is one of the most recognized welding quality certifications. Requirements include: education + work experience in welding inspection (with a points-based system), passing a three-part exam covering Fundamentals (Part A), Practical Application (Part B), and a Code Book (Part C — candidate chooses the code, e.g., AWS D1.1, API 1104, ASME IX). CWIs are required on structural, pressure vessel, pipeline, and aerospace fabrication projects. Senior CWIs (SCWIs) have additional experience and exam requirements. CWIs are also required for welder qualification testing oversight.

Flux in welding serves multiple functions: (1) Shielding — generates shielding gases (CO₂, CO) to protect the molten weld pool from atmospheric oxygen and nitrogen; (2) Slag formation — slag floats on the weld pool, physically protecting it from the atmosphere as it solidifies and controlling weld bead shape and cooling rate; (3) Deoxidation — flux contains deoxidizers (manganese, silicon) that react with oxygen; (4) Alloying — some flux systems add alloying elements (Cr, Ni, Mo) to the weld deposit; (5) Arc stabilization — flux components (potassium, sodium) improve arc stability. Slag MUST be thoroughly removed between passes to prevent slag inclusions — a common cause of weld rejections.

Welding positions:

- 1G/1F: Flat position — plate horizontal, welding from above. Easiest position; gravity helps control the weld pool.

- 2G/2F: Horizontal — groove is vertical, welding horizontally. Gravity pulls weld metal downward; requires technique adjustments.

- 3G/3F: Vertical — weld axis is vertical; welding up or down. Vertical-up (3G-up) is most common; requires weaving or stringer bead technique.

- 4G/4F: Overhead — welding from below; gravity pulls metal away from joint. Requires tight arc, fast travel, lower current.

- 5G: Pipe, horizontal fixed (axis horizontal) — requires all positions.

- 6G: Pipe at 45° fixed inclination — the most demanding test; qualifies the welder for all positions and all pipe work. Required by most pipeline and pressure vessel codes.

A welder qualified in 1G (flat) is NOT qualified for other positions. A 6G qualification qualifies for all positions.

WPS qualification process:

1. Weld the test coupon — using the proposed essential and nonessential variables as they will be used in production.

2. CWI witnesses the weld — the inspector verifies parameters during welding (current, voltage, travel speed, preheat, etc.).

3. Record variables on PQR — all parameters are documented on the Procedure Qualification Record.

4. Mechanical testing — bend test specimens, tensile specimens, and impact (Charpy V-notch) specimens are cut, prepared, and tested at a qualified test lab.

5. Write the WPS — the qualified PQR supports the production WPS; the WPS is then used by welders as their "recipe" for production welding. AWS D1.1 CWI or ASME AI (Authorized Inspector) acceptance may be required before the WPS is put into production.