Welder Qualifications Explained: 6G, 3G, TIG and MIG, and What to Specify
How welder qualifications work under ASME IX and AWS D1.1, what 6G, 3G, TIG and MIG mean, and which WPS details to put in a Saudi manpower request.
In Saudi industrial projects, welder qualifications depend on two separate variables: the welding position (such as 6G for fixed-inclined pipe or 3G for vertical plate) and the welding process (such as TIG/GTAW or MIG/GMAW). Specify both, with the material, thickness and welding procedure specification (WPS), so the supplier proposes welders qualified for the joints you will test them on.
Key takeaways
- 6G and 3G are test positions; TIG, MIG and SMAW are welding processes. A complete request names both.
- A 6G welder qualification (ASME Section IX) qualifies the craftsman for all plate and pipe positions (1G, 2G, 5G, 6G), which is why it is the widest position qualification.
- TIG (GTAW) is required for root passes and exotic alloys (stainless, duplex, Inconel), while MIG/FCAW or SMAW is used for rapid fill and cap passes.
- Industrial sites usually trade-test welders on arrival; sending the approved WPS with the request lets the supplier match welders to it.
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Positions and processes: why '10 welders' is not enough
On petrochemical, oil and gas, and major industrial projects across Jubail, Yanbu, Dammam, and Ras Al-Khair, a request that only says '10 welders' leads to failed trade tests and late mobilization.
Welder qualification is governed by codes such as ASME Section IX (Boiler and Pressure Vessel Code), AWS D1.1 (Structural Welding Code), and API 1104 (Pipelines). These codes qualify two separate things:
1. The Welding Position: Where the joint is located in physical space and whether the pipe or plate can be rotated (e.g., 1G, 2G, 3G, 4G, 5G, 6G). 2. The Welding Process: The technical method used to deposit weld metal (e.g., SMAW/Stick, GTAW/TIG, GMAW/MIG, FCAW/Flux-Cored).
When you engage welder supply services, matching the exact combination of position and process to your project's Welding Procedure Specification (WPS) is what decides whether the coupons pass.
The Welder Qualification Matrix: Positions, processes, and standards
The table sets out the four welder categories used on Saudi industrial sites, for piping engineers, QA/QC and procurement drafting a request.
| Qualification Code | Process / Method | Position & Geometry | Inspection Standard | Typical scope |
|---|---|---|---|---|
| 6G X-Ray Welder | GTAW (Root) + SMAW (Fill/Cap) or Full SMAW | Pipe fixed at 45° angle (no rotation allowed) | 100% Radiographic Testing (RT) / ASME IX | Refinery turnaround, cross-country pipelines, plant process piping, boiler tubes |
| TIG / Argon Welder | GTAW (100% Argon Gas Shield) | All positions (Pipe and Plate) | Visual + Dye Penetrant (PT) / RT | Stainless steel (304L/316L), duplex, alloy piping, instrumentation tubing |
| MIG / FCAW Welder | GMAW (Solid Wire) / FCAW (Flux-Cored) | 1G, 2G, 3G (Flat, Horizontal, Vertical) | Visual + Ultrasonic Testing (UT) / AWS D1.1 | Structural steel fabrication yards, tank pre-assembly, heavy skid frames |
| 3G Plate Welder | SMAW (E7018 / E6010) or FCAW | Vertical plate (uphill progression) | Visual + Guided Bend Test / AWS D1.1 | Structural building frames, industrial pipe racks, storage tank vertical seams |
What 6G qualifies under ASME Section IX
6G X-ray welders are priced above other welders because the test is harder and the qualification covers more.
In a 6G test, a pipe coupon is rigidly mounted at a 45-degree angle. The welder cannot rotate it, so each side is welded uphill, changing torch angle, body position and travel speed through the flat, vertical and overhead positions.
Under ASME Section IX, Table QW-461.9, successfully passing a 6G pipe qualification test qualifies the welder for: - All positions on pipe, within the diameter range the coupon size qualifies (ASME IX table QW-452.3). - All positions on plate (1G flat, 2G horizontal, 3G vertical, and 4G overhead). - Both groove and fillet welds across all joint geometries.
That breadth is why shutdown, turnaround and tie-in packages, where field joints come in every position, lean on 6G welders.
When TIG (argon) is required
6G describes the position. Gas tungsten arc welding (GTAW), called TIG or argon welding on Saudi sites, is about weld cleanliness and control of penetration.
Deploying a TIG / Argon welder is the normal choice in three cases:
1. Open-Root Passes on High-Pressure Pipe: When welding heavy-wall carbon steel or chrome-moly process piping, the root pass must be deposited using GTAW with an internal argon purge dam. TIG gives a clean internal bead with no slag, which is what radiography of the root is looking for. 2. Stainless Steel and High-Alloy Materials: Materials such as 304L, 316L, Duplex 2205, and Super Duplex will oxidize (sugar) on the backside if welded with stick electrodes without inert shielding. TIG with backing gas preserves the alloy's corrosion resistance. 3. Small-Bore Piping and Instrumentation: Hydraulic lines, turbine lubrication lines, and instrumentation tubing (under 2-inch diameter) cannot be welded with bulky stick electrodes; they require the precision arc control of TIG.
Request checklist for piping and QA/QC engineers
Put these six details in the request so the supplier can propose welders qualified for your joints:
1. Base Metal Specification: Specify material grade (e.g., Carbon Steel ASTM A106 Gr. B, Stainless Steel 316L, or P91 Alloy). 2. Diameter and Wall Thickness Range: State pipe outer diameter (e.g., 2" to 24") and schedule (e.g., Sch 40, Sch 80, Sch 160). 3. Welding Process Breakdown: State whether the joint requires GTAW root + SMAW fill/cap, full GTAW, or GMAW/FCAW. 4. Welder Position: Confirm whether 6G fixed pipe, 5G horizontal pipe, or 3G/4G structural plate is required. 5. Client Qualification Standard: Identify the applicable construction code (ASME B31.3 for process piping, ASME B31.1 for power piping, or AWS D1.1 for structural steel) and whether client pre-qualification coupon testing is mandatory. 6. Supporting Trades: Confirm whether welders will work with pipe fabricators for shop spooling or pipe fitters for site erection.
Send these details through the manpower request form to check availability of 6G and TIG welders for your site.
For welders on industrial sites, the city pages cover what local plants usually ask for: welder supply in Jubail and welder supply in Yanbu.
Frequently asked questions
Does a 6G welder qualification automatically qualify a welder for all pipe welding?
In terms of position, yes: under ASME Section IX, qualifying on a 6G pipe coupon qualifies the welder for all pipe and plate positions. However, the qualification is still restricted to the specific welding process (e.g., GTAW vs. SMAW), filler metal group (F-Number), and base metal thickness range specified on their Welder Performance Qualification (WPQ) record.
What is the difference between a 6G welder and a TIG welder?
6G refers to the welding position (pipe fixed at a 45-degree angle), whereas TIG (GTAW) refers to the welding process (using an inert argon gas shield and tungsten electrode). Many industrial pipe welders are qualified as 'TIG + Arc 6G' welders, meaning they use TIG for the critical root pass and SMAW (Stick) for the filler and capping passes.
Do client sites in Saudi Arabia require welders to be re-tested on arrival?
Usually, yes. On petrochemical, refinery and energy sites, third-party certificates get a welder to the test, not onto the job. Site QA/QC normally runs a trade test where the welder welds a coupon under the site's approved WPS, followed by visual inspection, bend testing, or radiographic (X-ray) examination before a site pass is issued.
What documents should accompany a welder's CV in a technical proposal?
Ask for their Welder Performance Qualification (WPQ) record, third-party test laboratory certificates (indicating process, position, P-Number, and F-Number), previous Aramco/SABIC approval cards if applicable, an active Iqama with a matching welder profession code, and a fit-to-work medical certificate.