Does D1.1 Specify a Maximum Interpass Temperature?
No. D1.1:2025 does not impose a blanket maximum interpass temperature across all steels. The code only requires a maximum interpass temperature on the WPS in two situations: when CVN (Charpy V-notch) testing is specified by the contract documents, or when the base metal specification itself carries a limit. For the vast majority of structural steels — A36, A572, A588, A992 — there is no code-mandated upper bound on interpass temperature.
This surprises many fabricators who assume a universal maximum applies. The confusion often stems from shop practices (many shops set a 500–600°F limit as internal policy) or from conflating D1.1 with other codes. ASME Section IX, for example, treats interpass temperature as a supplementary essential variable when impact testing is required — but that is a different code with different rules.
Steels With Specific Maximum Interpass Limits
D1.1:2025 Table 5.11 imposes maximum interpass temperature limits only on quenched and tempered (QT) and high-performance steels in Groups V and VI. These steels achieve their mechanical properties through controlled heat treatment, and excessive interpass heat can temper the base metal, reducing strength and toughness below specified minimums.
| Steel | Thickness | Max Interpass |
|---|---|---|
| A514, A517, HPS100W | ≤ 1-1/2 in [40 mm] | 400°F (200°C) |
| A514, A517, HPS100W | > 1-1/2 in [40 mm] | 450°F (230°C) |
| HPS70W | ≤ 1-1/2 in [40 mm] | 400°F (200°C) |
| HPS70W | > 1-1/2 in [40 mm] | 450°F (230°C) |
In practice, this means if you are welding A514 plate and the joint has cooled to 300°F between passes, you are within limits. If it is still at 420°F, you must wait before depositing the next pass. Use a contact pyrometer to verify — do not guess on QT steels.
When CVN Testing Requires a Maximum
When the contract documents specify CVN (Charpy V-notch) testing for the weldment, D1.1:2025 requires that the maximum interpass temperature be stated on the WPS. Excessive interpass temperature degrades toughness in the heat-affected zone by allowing grain coarsening. The specific maximum value is not prescribed by D1.1 — it must be determined by the engineer based on the required toughness properties, the steel grade, and the welding process.
For example, a bridge project requiring CVN testing at −20°F might specify a 450°F maximum interpass for A709-50W plate to ensure adequate HAZ toughness. A building project with no CVN requirement on the same steel has no code-mandated maximum.
How Hot Is Too Hot Between Weld Passes?
For non-QT steels without CVN requirements, D1.1 sets no limit — but that does not mean temperature is irrelevant. Excessively high interpass temperatures cause wider heat-affected zones, increased distortion, reduced weld metal yield strength, and coarser grain structure. Most structural fabrication shops set internal limits of 500–600°F even when not required by code.
Field tip: If you are welding A992 beams with no CVN requirement, D1.1 does not require a maximum interpass temperature. But if the steel is glowing red between passes (above about 800°F), you are causing metallurgical damage regardless of code requirements. Let the joint cool. In practice, 500°F is a reasonable shop limit for most non-QT structural steels.
Where to Measure Interpass Temperature
Per D1.1:2025 §5.7, interpass temperature is measured on the base metal adjacent to the weld joint — not on the weld metal itself. The measurement distance depends on material thickness.
§5.7. Measure on base metal, not weld metal.For material less than 1-1/2 in thick, measure at a distance equal to twice the base metal thickness from the weld toe. For material 1-1/2 in or thicker, measure at a distance equal to the base metal thickness, but not less than 3 in from the weld toe. Use a contact pyrometer or temperature-indicating crayon for reliable readings.
How to Set Interpass Temperature on Your WPS
The minimum interpass temperature on the WPS equals the minimum preheat temperature from D1.1 Table 5.11. The maximum interpass temperature is required only when CVN testing is specified or the steel has a code-mandated limit. When no maximum is required by code, many fabricators still record a shop-standard maximum as a quality control measure.
Per Table 5.5 essential variable requirements, both minimum and maximum interpass temperatures (when applicable) must appear on the WPS. A change in the maximum interpass temperature is an essential variable that requires requalification of the procedure.
CWI Exam Tip
CWI Part C question pattern: A question may describe a scenario with A514 steel and ask whether a specific interpass temperature is acceptable. The key fact to remember: A514 maximum interpass is 400°F for material ≤1-1/2 in and 450°F for material >1-1/2 in. If the scenario describes A36 or A992, the answer is that D1.1 has no general maximum interpass requirement — the common misconception of a universal 550°F or 600°F limit has no basis in the code.