AWS standard · reference card
AWS D1.6: scope, alloy grade and what it qualifies
Does AWS D1.6 govern your welded stainless structure, and does the alloy grade match the code's qualification and sensitization considerations? Scope decision flow and the records that evidence a qualified weld.
- Designation
- AWS D1.6
- Issued by
- AWS
- Title
- Structural Welding Code — Stainless Steel
- Edition
- Confirm the edition your contract cites.
AWS D1.6 is the stainless-steel member of the AWS D1 structural-code family, and its most consequential scope decision happens before the first arc is struck: which stainless grade is actually being welded. Austenitic, duplex, ferritic and martensitic grades do not share one qualification logic or one heat-input response, and a procedure record proven on one says nothing reliable about another.
The concern that separates stainless structural work from the carbon-steel route is heat-affected-zone sensitization — a grade-dependent response to welding heat that can leave a corrosive-service joint more susceptible to intergranular attack than the parent plate. That grade dependence is why identifying the grade comes before deciding how tightly interpass temperature needs to be controlled.
Therness’s stainless welding monitoring guide covers the same mechanism from a thermal-monitoring angle. Therness equipment measures interpass temperature and heat input continuously through a multi-pass stainless joint, tied to the welding process record for the grade and joint in question rather than a single spot check.
Scope: does it apply to your job?
Applies to
- Welded stainless steel structural work built under the AWS D1.6 route, where at least one material joined is stainless
- Welder and welding procedure qualification for stainless structural welding, prequalified joints, and acceptance inspection
- Statically and cyclically loaded stainless structural connections
Does not apply to
- Carbon and low-alloy structural steel, covered by AWS D1.1
- Aluminium structures, covered by AWS D1.2
- Piping and pressure-retaining stainless components, governed by the applicable piping or vessel code instead
- Stainless sheet below the code's minimum base-metal thickness for structural design stress
Applicability decision flow
| Question | If yes | If no |
|---|---|---|
| Is the structure a welded stainless weldment within this code's route, subject to design stress? | AWS D1.6 is the governing structural welding code. | Carbon and low-alloy steel go to AWS D1.1; aluminium goes to AWS D1.2. |
| Has the stainless grade — austenitic, duplex, ferritic or martensitic — been matched to the code's qualification requirements? | Continue; the grades do not share one qualification or heat-input logic. | Identify it first — a procedure on an austenitic grade says nothing about a duplex or ferritic one. |
| Does the joint sit in a corrosive-service environment where heat-affected-zone sensitization is a design concern? | Interpass temperature and heat input control become part of the acceptance argument, not just weld geometry. | Proceed under the code's standard qualification and acceptance route. |
| Is the joint and procedure drawn from AWS D1.6's prequalified list? | It may be used without a separate qualification test, subject to meeting every prequalification condition. | Qualify the procedure by test, or directly to AWS B2.1 where the edition in force permits it. |
What proves conformity, and what only supports it
Conformity is decided by inspection and testing against the criteria the standard and the contract set. The records below are evidence that the process was held where it was qualified; they support an inspection result, they never replace one.
| Requirement | Record produced | Source |
|---|---|---|
| Evidencing interpass temperature stayed inside the qualified band on a corrosive-service connection | Non-contact interpass measurement recorded on every pass, not spot-checked | HeatCam IR-C |
| Evidencing heat input per pass stayed inside the qualified range | Arc energy computed per pass from measured current, voltage and travel speed | WeldTrace |
| A per-weld, grade-tagged record available for qualification and continuity evidence | Timestamped process export tied to welder, procedure and material identifier | HeatCore AI |
Questions engineers ask about AWS D1.6
Does AWS D1.6 cover stainless steel piping under pressure?
No. Piping and pressure-retaining stainless components are excluded; the applicable piping or vessel code governs those instead.
Can one procedure qualification cover both austenitic and duplex stainless grades?
No. AWS D1.6 does not share one qualification logic across grades; a procedure proven on one says nothing about a grade in a different group.
Is there an alternative to qualifying under AWS D1.6's own clause?
Some editions allow qualifying directly to AWS B2.1 — confirm which route the edition in force permits.
Evidence the process, not just the paperwork
Therness records what the machine actually delivered on every weld — parameters, thermal signature and a per-weld trail — so a conformity argument rests on measurements instead of recollection.
