AWS D1.1:2025 Update: What Changed in Postweld Heat Treatment Requirements

AWS D1.1/D1.1M — the Structural Welding Code for Steel — got its latest revision in the 2025 edition, and one of the more consequential changes for shops that specify postweld heat treatment (PWHT) is easy to miss if you're still working from an older copy of the code.

What changed. Clause 7.8 now requires PWHT to be specified in contract documents or approved by the engineer, performed in conformance with a Welding Procedure Specification (WPS) that was itself qualified with PWHT, and documented through a written procedure covering heating rate, holding temperature, holding time, cooling rate, and heating method. The code also raised the initial maximum furnace temperature from 600°F to 800°F.

Why the documentation change matters more than the temperature change. The furnace temperature adjustment is a technical detail. The documentation requirement is the part worth paying attention to: PWHT that was previously handled as shop practice now needs a written procedure with specific parameters, tied to a WPS that was qualified with PWHT in the first place. A weld that was heat-treated correctly but documented loosely is now a nonconformance waiting to be found in an audit — even if the weld itself is sound.

What to check. If your shop performs structural steel welding under D1.1 and PWHT is part of your process, it's worth confirming three things: your WPS was qualified with PWHT (not added as an afterthought), your written PWHT procedure actually specifies heating rate, holding temperature, holding time, cooling rate, and heating method, and your furnace equipment and monitoring can substantiate the parameters you're documenting.

This is exactly the kind of code-detail gap that surfaces during a CWI weld inspection rather than before one. Lion NDT's Welding Inspection services include verifying that your documentation — not just your welds — actually matches what the current edition of the governing code requires.