EN 10253-2 Type B P5 · X12CrMo5 · 5Cr-0.5Mo PWHT Mandatory

1.7362 (P5) Pipe Fittings

EN 10253-2 Type B buttweld pipe fittings in 1.7362 — P5 CrMo alloy steel (X12CrMo5, 5Cr-0.5Mo). The 5% chromium content places P5 on a favourable position on the API 941 Nelson curve, providing resistance to high-temperature hydrogen attack (HTHA) and sulfidation in oil refinery service. Used in hydrotreater, hydrocracker, and atmospheric distillation unit (ADU) process piping at elevated temperatures.

Cr Content

ASTM Equivalent

WP5 / ASTM A335 P5

Key Standard

API 941 (Nelson)

PWHT Mandatory

1.7362 (P5) requires post-weld heat treatment. PWHT temperature: 720–760°C. As-welded hardness exceeds limits and the HAZ is susceptible to hydrogen cracking without PWHT. All fittings supplied with PWHT documented on EN 10204 3.1 certificate.

Refinery CrMo Grade by Cr Content

Grade	W.Nr.	Cr %	API 941 Advantage	Typical Refinery Use
P11	1.7335	1.25%	Limited	Low-temp steam, secondary piping
P22	1.7380	2.25%	Moderate	Hydrotreater, hydrocracker HP piping
P5 (this grade)	1.7362	5%	Good — Nelson curve margin	ADU hot section, crude transfer
P9	1.7386	9%	Excellent	Highest-temp refinery, FCCU

Cross-References

W.Nr.	1.7362
EN Name	X12CrMo5
ASTM Grade	WP5 / P5
Composition	5Cr-0.5Mo

Welding

Filler: ER80S-B6 (AWS A5.28). Preheat 200°C minimum. PWHT 720–760°C. No high-Mn or high-Si fillers.

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