What steels have a maximum interpass temperature under D1.1?

Under D1.1:2025 Table 5.11, only quenched and tempered steels in Group V and VI have specific maximum interpass limits. A514 and HPS100W require a maximum of 400°F (200°C) for material up to 1-1/2 in thick and 450°F (230°C) for material over 1-1/2 in thick. HPS70W carries the same limits. These steels are sensitive to excessive heat input because it can temper the base metal and reduce mechanical properties.

Is 600°F too hot for interpass temperature?

It depends on the steel. For A514, A517, HPS70W, and HPS100W, 600°F far exceeds the 400–450°F maximum and would violate D1.1 Table 5.11. For common structural steels like A36, A572, and A992, D1.1 sets no maximum interpass temperature, so 600°F is not a code violation. However, excessively high interpass temperatures on any steel can reduce mechanical properties and increase distortion. In practice, many fabricators limit interpass to 500–600°F on non-QT steels as a quality measure, but this is shop practice rather than a D1.1 requirement.

When does CVN testing require a maximum interpass temperature?

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. This is because excessive interpass temperature can degrade toughness properties in the heat-affected zone. The specific maximum value is not prescribed by D1.1 itself — it must be determined by the engineer based on the toughness requirements and the steel being welded.

How do you 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. 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. An infrared thermometer may be used but can read low on shiny or reflective surfaces.

How do you set interpass temperature on a 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 (A514, HPS70W, HPS100W). When no maximum is required by code, many fabricators still record a shop-standard maximum (typically 500–600°F for non-QT steels) as a quality control measure. The WPS must list both minimum and maximum when applicable per Table 5.5 essential variable requirements.

Maximum パス間温度 — D1.1:2025

Does D1.1 Specify a Maximum Interpass Temperature?

No. D1.1:2025 does not impose a blanket maximum interpass temperature across all steels. The 基準 only requires a maximum interpass temperature on the WPS in two situations: when CVN (Charpy V-notch) testing is specified by the 契約図書, or when the 母材仕様書 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 補助重要変数 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 限界値 only on quenched and tempered (QT) and high-performance steels in Groups V and VI. These steels achieve their 機械的性質 through controlled 熱処理, and excessive interpass heat can temper the base metal, reducing 強度 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 溶接 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 確認 — 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 熱影響部 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 溶接工程.

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 溶接 Passes?

For non-QT steels without CVN 要求事項, D1.1 sets no limit — but that does not mean temperature is irrelevant. Excessively high interpass temperatures cause wider heat-affected zones, increased 溶接ひずみ, reduced 溶接金属 yield strength, and coarser grain structure. Most 鉄骨製作 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 板厚.

Interpass temperature measurement location per D1.1:2025 §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 溶接止端. 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 最小 interpass temperature on the WPS equals the minimum 予熱温度 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-規格 maximum as a quality control measure.

Per Table 5.5 重要変数 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.