P91 パイプと F91 フランジを適合させる方法

技術ニュースレビュー済み: 3 8月 2026による SASA FLANGE 技術コンテンツチーム

直接の答え

Match ASTM A335 P91 pipe with an ASTM A182 F91 flange by confirming that both belong to the approved Grade 91 line class, sizing the flange bore and weld end for the actual pipe wall, and using a qualified Grade 91 welding and PWHT procedure. Verify heat treatment, hardness and heat-number traceability for the flange; chemistry alone is not enough.

重要なポイント

P91 describes pipe, while F91 describes a forged piping component.
The bore and weld-end transition must match the ordered pipe wall.
学年 91 reliability depends on thermal history, 溶接と硬度の制御.

P91 and F91: related grades, different product forms

ASTM A335 P91 applies to seamless ferritic alloy-steel pipe for high-temperature service. ASTM A182 F91 applies to forged or rolled piping components such as flanges. The design intent is a compatible Grade 91 material system, but each product must meet its own specification, 熱処理, testing and marking requirements.

Do not treat an F91 flange as a generic high-alloy replacement. The connected valve body, 継手, branch components, weld metal and fabrication plan should all be reviewed within the same line class.

Dimensional matching at the butt weld

Nominal pipe size alone does not define the weld preparation. State the P91 pipe schedule or actual wall, any minimum-wall purchasing basis, corrosion allowance and required transition. The flange manufacturer can then machine the bore and weld end to the approved detail.

Check	Required input	Desired result
Outside diameter	NPS and pipe dimensional standard	Correct alignment
肉厚	Schedule or specified minimum wall	Approved bore and taper
Weld preparation	Project detail and WPS	Qualified joint geometry
Flange rating	設計条件, material group and ASME class	Adequate pressure-temperature rating

Control the Grade 91 thermal cycle

学年 91 performance depends on a properly produced and preserved microstructure. The flange should be supplied in the required normalized-and-tempered condition with documented mechanical and hardness results. During welding, control preheat, パス間温度, consumables, interruption rules and PWHT under an approved procedure.

PMI is important for preventing alloy mix-ups, but it does not confirm microstructure, tempering or internal quality. Hardness mapping and any specified surface or volumetric NDE complete different parts of the verification plan.

学年 91 joint dossier

P91 pipe and F91 flange material certificates linked by item and heat number
Approved flange drawing showing bore and weld-end transition
Heat-treatment records and mechanical test results
PMI and hardness reports with locations and acceptance limits
Qualified WPS/PQR and welder qualification
予熱, interpass and PWHT charts for the production weld
Required MT/PT, UT/RT and final visual or dimensional reports

Retain these records as a connected turnover package. Isolated certificates are less useful when they cannot be linked to the installed joint.

よくある質問

Are P91 and F91 the same material?

They are related Grade 91 alloy designations for different product forms: P91 for pipe and F91 for forged or rolled piping components.

Can PMI prove an F91 flange is correctly heat treated?

いいえ. PMI checks chemistry. Heat-treatment records, mechanical results, hardness and applicable metallurgical controls are also required.

What pipe detail is needed to order an F91 weld neck flange?

Provide the pipe specification, NPS, schedule or actual wall basis, and the approved weld-end transition detail.

参照される主な規格

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