3G & 6G welder certification for shipbuilding, what the trade test actually checks

A 3G is a plate welder in the vertical-up position. A 6G is a pipe welder in the fixed-45-degree position, all-around. Shipyards screen on both before the worker reaches the rate-floor. The certification standard (EN ISO 9606-1 in Europe, ASME Section IX on cross-Atlantic work, AWS D1.1 on the structural side) decides what the test looks like and how the coupon gets read.

The position codes, and what shipyards mean when they ask

The position numbers come from the welding standards and they are not interchangeable. 1G is flat plate, 2G is horizontal plate, 3G is vertical plate, 4G is overhead plate. The pipe codes run 1G (rotated horizontal pipe), 2G (vertical pipe rotated), 5G (horizontal pipe fixed), 6G (45-degree pipe fixed). 6GR is 6G with a restriction ring, the hardest test.

When a Croatian shipyard production manager says "we need 3Gs", the trade is: MAG or MIG welding on plate, vertical-up, on hull blocks or structural sections. The pay rate sits at the entry-band for the welder pool. The test coupon is 10mm plate, 3.2mm wire, a single-V or double-V groove, and the inspection runs visual and bend, sometimes radiographic if the production manager wants a higher confidence on the panel.

When the same manager says "we need 6Gs", the trade is: TIG-root with MAG or MIG fill on process piping, sea-water cooling lines, ballast systems, anything pressurised. The pay rate sits 25-45% above the 3G band. The test coupon is a fixed pipe, 6 inches or 4 inches schedule 80, a single-V groove. The inspection runs visual, bend and radiographic. The pass rate on a fresh-source 6G in Croatia runs around 60-65% in a yard's own re-test booth. On a candidate we have screened in Kathmandu or Mumbai with origin-side X-ray, the pass rate rises to 85-90%.

The standards, EN ISO 9606-1, ASME IX, AWS D1.1

Three standards govern welder qualification for shipbuilding work, and Croatian yards run against all three depending on the client.

EN ISO 9606-1 is the European standard for fusion welding qualification on metallic materials. Most Croatian-flag work, most Adriatic shipbuilding for European owners, and most refit work runs against EN ISO 9606-1. The certification is valid for two years if the welder works the process continuously; it lapses if the welder steps off the process for six months without a re-test.

ASME Section IX is the American Society of Mechanical Engineers code for welding and brazing qualification. Cross-Atlantic work, yachts built for American owners, offshore-sector pipe work, anything contracted under ASME B31 piping codes runs the ASME qualification track. ASME IX is procedure-tighter. The PQR (Procedure Qualification Record) and the WPS (Welding Procedure Specification) are the documents the welder works against.

AWS D1.1 is the American Welding Society structural code. AWS D1.1 governs structural steel, hull blocks, deck plates, the heavy-section work that does not see pressurised media. AWS D1.1 has its own position codes and its own test coupons. A welder qualified to AWS D1.1 in the 3G position is not automatically qualified to EN ISO 9606-1 in the same nominal position. Cross-recognition between standards is a documented procedure, not an automatic conversion.

A welder out of a Filipino TESDA programme typically holds AWS D1.1. A welder out of an Indian ITI carries EN ISO 9606-1 or the Indian equivalent. A Nepali welder out of CTEVT runs on EN ISO 9606-1 or AWS D1.1 depending on the training centre. The standard the welder holds and the standard the yard works against do not always match on day one. We resolve that in the screening phase, before the visa stamp.

What the trade test actually checks

Inside the test booth, the welder gets:

A welding machine set to the procedure-defined parameters. A test coupon prepared to the standard's groove geometry. Filler material specified by the WPS. The destination yard's safety briefing.

The welder runs the joint. The coupon goes to inspection: visual first (porosity, undercut, weld profile, slag), bend test second (face bend and root bend on plate, four-bend on pipe), radiographic third on critical-service welds. Cracks, lack of fusion or incomplete penetration above the standard's threshold and the coupon fails. Most failure points sit at the start and stop of the bead, not the middle.

For 6G, add the X-ray reading. The radiographer is qualified to ASNT Level II or PCN equivalent. A senior welder cannot self-certify the coupon. This is where the day-count gets eaten: X-ray booking, film development (or digital plate read), the radiographer's report, the yard NDT lead's sign-off. A two-week buffer on a 6G panel of 30 welders is the realistic timeline.

MAG, MIG, TIG, what each acronym buys you

MAG (Metal Active Gas) is the high-volume process for hull-block work. The shielding gas is CO₂ or a CO₂-argon mix. Deposition rates are high, the welder moves fast, the joint is forgiving on plate. Most shipyard 3G work is MAG.

MIG (Metal Inert Gas) uses pure argon or argon-helium. Lower deposition than MAG but cleaner on non-ferrous and stainless. Yacht-finish work and aluminium runs more MIG than MAG.

TIG (Tungsten Inert Gas) uses a non-consumable tungsten electrode and a separate filler rod. Slower than MAG or MIG but produces the highest-quality root pass. Almost every pressurised pipe weld starts with a TIG root and finishes with MAG or MIG fill. That combination is what a 6G welder typically runs.

The trade test does not just check that the welder can run the process. It checks the welder can run the specific process the WPS calls for, on the specific material thickness, in the specific position. A 3G plate welder with vertical-up MAG technique is not automatically a 6G pipe welder. The corridor's strength on one band does not predict the other.

The certification chain in practice

A fresh-source welder from Nepal into a Croatian shipyard runs through this chain: in-country trade test at the Werklist screening centre (visual + bend, X-ray sample on 6G), document attestation through DOFE, embassy visa stamp, arrival in Croatia, yard re-test booth on day one. Croatia's yards run their own re-test booth because the production manager wants to see the coupon themselves before the worker reaches the rate-floor.

The re-test on day one fails roughly 10-15% of welders we have already screened in origin. The failure modes split: machine-parameter mismatch (the origin-test booth ran 220A, the yard runs 195A on the same WPS), groove preparation different from origin practice, coupon-start fatigue after a 14-hour transit. We re-coupon those welders on day two or day three. Most pass on the second run.

For more on the corridor-by-corridor mix and how the trade ratio shapes a 200-welder campaign, see the shipbuilding workforce master guide and the 3G/6G mix article.

What we screen for, before the visa stamp

The corridor screening runs against the yard's specific WPS and PQR, not a generic test. The shipyard sends us the procedure pack. We run the coupon under those parameters in Kathmandu, Mumbai, Cebu or Manila. We send the coupon photographs, the bend results and on 6G the X-ray plate to the yard NDT lead by email. The yard signs off on the panel before we book the visa appointment.

This eliminates the production-manager call where 40 of 200 welders fail the day-one re-test. It also reduces the re-coupon overhead at the yard from a five-day buffer to a one-day buffer.

If you are scoping a shipbuilding campaign (welder bands, standard, re-test confidence), start with a corridor-fit conversation. The number sits on the Zagreb branch page.