Short answer: Welding positions are coded 1 through 6 by joint orientation — flat is fastest and cleanest, vertical and overhead slow the work and raise defect risk, and the 6G pipe position at a 45° incline is the hardest certification because it combines every angle.
At a Glance
The Position Codes
The number sets the joint attitude and the letter the weld type: G for groove, F for fillet. 1 is flat (work beneath the torch, gravity helps), 2 horizontal, 3 vertical, 4 overhead, and 5/6 for pipe — 5G is a fixed horizontal pipe (roller-restricted) and 6G is a fixed pipe at a 45° incline that forces the welder through every position. Practice for each family is in How To Weld Stainless Steel, How To Weld Carbon Steel 그리고 알루미늄 용접 방법, with consumables per Welding Consumables Guide.
Why Position Matters
Out of flat, molten pool control is harder, so porosity and lack of fusion rise unless technique adapts — the flaw catalogue in Weld Defects Guide and the inspection in Metal Ndt Guide reflect that. Heat input and preheat still follow the carbon equivalent in Steel Carbon Equivalent Guide, so position compounds the difficulty of hard-to-weld steels.
Pipe & Certification
Pipe welds dominate the 5G/6G tests because fixed pipe cannot be rotated to flat. We supply the pipe — Steel Pipe Supplier, Stainless Steel Pipe Supplier, Erw Vs Seamless Pipe — and the fittings used in those joints, and we handle dissimilar transitions per Dissimilar Metal Welding Guide. After welding, stress relief per Stress Relieving Vs Annealing stabilises the assembly.
Get a Quote
Tell HXSCO your requirements and we will respond with a competitive quote and lead time.
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1 flat, 2 horizontal, 3 vertical, 4 overhead, 5 pipe (fixed horizontal), 6 pipe at 45° incline. The letter G is groove weld, F is fillet.
6G — a fixed pipe welded at a 45° incline — is considered the hardest because the welder must work through flat, vertical, overhead and everything between in one joint.
Gravity holds the molten pool in place and slag floats clear, so penetration and bead shape are easier to control and defect rates are lowest.
A certification test where a pipe is fixed at a 45° angle and welded without rotation, proving the welder can make sound welds in all positions on pipe.
Yes. HXSCO supplies carbon, stainless and alloy pipe and the full fitting range, plus dissimilar-metal transition joints, with mill certificates.
Source Weld-Ready Pipe from HXSCO
HXSCO supplies carbon, stainless and alloy pipe and fittings for welded fabrication with mill certificates and bevel prep on request. Send your sizes and quantity for a quote.