PWHT route and record guide · AWS D1.1
Does a PWHT change need a revised WPS or PQR requalification?
The answer depends on the current WPS basis, whether PWHT is added or removed, whether its temperature or time range changes, and whether CVN qualification applies. The WPS, PQR and production heat-treatment record answer different questions.
Decision matrix by procedure route
| Current basis | Proposed PWHT change | Code review | Decision boundary |
|---|---|---|---|
| New or revised Clause 5 prequalified WPS | Add PWHT or establish PWHT conditions. | Clause 5.9 permits this route only when its full conditions are met, including Engineer approval, strength/material restrictions, no notch-toughness testing requirement, adequate weld-metal strength and ductility evidence after PWHT, and compliance with 7.8. | If any 5.9 condition is not met, do not label it prequalified under 5.9. Identify the applicable tested qualification route and project approval basis. |
| Existing PQR-supported WPS | Add or delete PWHT. | Table 6.6(35) lists an increase or deletion of PWHT as a requalification variable for the covered processes. | Assess against the applicable process and complete qualification path. Do not infer that an existing PQR covers a different PWHT status. |
| CVN-qualified PQR-supported WPS | Change PWHT temperature and/or time range. | Table 6.8(9) is supplementary to the normal essential-variable review. The PQR test must experience 80% of total hold time; that total may be applied in one or more heat cycles. | Check the original PQR and PWHT record against the full proposed range. No generic cycle can be assumed from the percentage rule. |
| Any route | Production cycle parameters or measured cycle depart from the applicable written procedure. | Review the approved WPS and written PWHT procedure against Clause 7.8, contract requirements, and actual time-temperature records. | A conforming WPS/PQR does not prove that a particular production heat-treatment cycle complied. |
Clause 5: prequalification has specific PWHT gates
Clause 5.9 is conditional. PWHT is prequalified only with Engineer approval and when every listed condition is met: specified minimum yield strength is at or below 50 ksi [345 MPa]; the base metal is not Q&T, Q&ST or TMCP and has not gained higher properties through cold work; base metal, HAZ and weld metal have no notch-toughness testing requirement; information supports sufficient weld-metal strength and ductility in the PWHT condition; and the treatment meets Clause 7.8.
That is a route decision, not a general statement that PWHT is prohibited whenever one condition fails. It means the Clause 5.9 prequalified basis is unavailable; determine the applicable Clause 6 qualification and approval requirements from the actual materials and project. Q&T, Q&ST, PH and TMCP materials also have a specific caution in 7.8.1; where PWHT is required, use the material producer's recommendation and obtain Engineer approval.
For a prequalified WPS, Table 5.5 requires PWHT status and conditions to be stated. If production moves outside the written WPS conditions, revise the WPS and reassess the entire Clause 5 basis. A Table 5.5 operating tolerance does not replace the 5.9 eligibility conditions or 7.8 procedure requirements.
Existing PQR: separate PWHT status from PWHT cycle range
Table 6.6(35) and Table 6.8(9) answer different questions. Under Table 6.6, adding or deleting PWHT from a PQR-supported procedure is a requalification trigger. Where CVN requirements apply, Table 6.8 adds a supplementary variable for a change in PWHT temperature and/or time range. A review limited to one of these entries is incomplete when both apply.
Table 6.8(9) states that the PQR test must be subjected to 80% of the total holding time. The combined time may be imposed in a single cycle or multiple cycles. This does not mean any arbitrary production cycle is covered: compare the proposed PWHT temperature/time range to what the PQR actually experienced, alongside Table 6.6 and the other applicable variables.
For preparation from existing records, capture the actual PQR PWHT temperature, hold duration and cycle count from the controlled record. If those records are missing, illegible, or do not establish the tested condition, leave the PWHT scope unresolved. Do not backfill assumed temperatures, soak times or cycles.
Three records, three different jobs
| Record | What it must establish | Useful fields to preserve |
|---|---|---|
| WPS | The production welding and PWHT conditions authorized for use. | PWHT yes/no; specified temperature and time range; applicable procedure limitations and contract requirements. |
| PQR and qualification report | The actual variables and test evidence supporting the qualified WPS. | Actual coupon PWHT state, temperature/time/cycle record, CVN applicability and reports, tested materials and process; compare against Tables 6.6 and 6.8. |
| Written production PWHT procedure and cycle record | How a particular component is heated, monitored, held, cooled and documented. | Heating method; furnace/load placement temperature when applicable; heating rate; hold temperature/time; cooling rate and controlled-cooling stop temperature; thermocouple number/locations; recorded time-temperature cycle. |
Clause 7.8 requires a written PWHT procedure with the applicable details and requires the time-temperature cycle to be recorded. The PQR's qualification evidence is not a substitute for the production component's actual cycle chart or record.
A practical review sequence
- Identify the contract edition, whether CVN applies, whether PWHT is required or permitted, and the approval authority.
- Classify the procedure as Clause 5 prequalified or PQR-supported. Locate the controlling WPS, PQR and heat-treatment records.
- For Clause 5, test every Clause 5.9 gate and confirm the stated WPS PWHT conditions satisfy 7.8. If the basis is unavailable, do not assign prequalified status.
- For an existing PQR, check whether PWHT is added or removed under Table 6.6(35). If CVN applies, also compare the temperature and time range under Table 6.8(9), using the recorded PQR cycle evidence.
- Review the production PWHT procedure and the actual cycle against Clause 7.8 and project requirements. Record any missing input as unresolved instead of supplying a generic cycle.
Code basis and sources
This guide follows AWS D1.1/D1.1M:2025 base edition plus the registered base-edition errata dated July 28, 2026. AMD1 is excluded. The contract's specified edition governs the project; a different edition needs its own check.
Primary provisions: Clauses 5.8–5.9 (printed page 67; PDF page 94); Table 5.5 (printed page 72; PDF page 99); Table 6.6(35) (printed pages 149–151; PDF pages 176–178); Clause 6.8.1 and Table 6.8(9) (printed pages 149 and 154; PDF pages 176 and 181); Clauses 7.8.1–7.8.3.3 (printed pages 197–198; PDF pages 224–225); Tables 7.2–7.3 (printed page 212; PDF page 239). Check all process-specific marks, notes and project restrictions in the governing code.
Read the edition and errata basis. See WPS change and requalification decisions and CVN requirements and procedure qualification.
Public source links last checked October 7, 2026.
Keep tested PWHT conditions traceable to the PQR and production cycle evidence.