鍛造合金鋼フランジのNDT検査

鍛造合金鋼フランジのNDT検査方法

Technical guideレビュー済み: 30 7月 2026Prepared by SASA FLANGE 技術コンテンツチーム

直接の答え

Forged alloy steel flange inspection can combine visual testing (VT), magnetic-particle testing (MT), liquid-penetrant testing (PT) and ultrasonic testing (ユタ州). Each method finds different discontinuity types. The correct method, extent, timing and acceptance criteria must be specified by the governing standard, code and purchase order.

重要なポイント

No single NDT method proves total flange integrity.
MT suits ferromagnetic alloy steel surfaces; PT is useful for surface-breaking flaws on many nonporous materials.
UT technique and calibration must account for flange geometry and the required examination volume.

What each NDT method contributes

Method	Best suited to	Key limitation
VT	Surface condition, laps, cracks, damage, workmanship and marking	Only visible conditions
MT	Surface and near-surface discontinuities in ferromagnetic steel	Not applicable to austenitic stainless grades
PT	Surface-breaking discontinuities on nonporous surfaces	Does not find buried flaws
ユタ州	Internal discontinuities within an examinable forging volume	Geometry, grain structure and scan access affect coverage

Inspection stage matters

Examination before final machining may provide access to the forging volume, while final-surface examination can detect machining or finishing damage. Heat treatment should occur before the specified final NDT stage when the procedure requires examination of the delivered condition.

Repairs, re-heat treatment or weld build-up can trigger re-examination. The purchase order should state hold and witness points.

Acceptance criteria must be written

A report that says “UT OK” is weak evidence unless it identifies the procedure, calibration, coverage, sensitivity, acceptance standard, operator qualification and item traceability. Different projects can apply different allowable indications.

Define the code paragraph, ASTM practice, owner specification or approved procedure that governs acceptance.

What a useful NDT report includes

Flange description, heat number and item identification
Method, written procedure and acceptance criteria
Equipment, probe or consumable details and calibration
Examination surfaces, coverage and stage
Indication records and disposition
Operator name, certification level, date and authorization

よくある質問

Is MT better than PT for F22 flanges?

MT is often efficient for ferromagnetic F22 surfaces and can detect near-surface indications, but the project procedure determines the required method and sensitivity.

Does UT replace mechanical testing?

いいえ. UT examines internal discontinuities; tensile, impact and hardness tests address material properties.

Should finished sealing faces receive NDT?

Final visual inspection is essential, and surface NDT may be specified. The method must avoid damaging or contaminating the finished face.

参照される主な規格

Always verify the edition specified by the purchase order and obtain the complete controlled standard for design and acceptance.

合金鋼フランジの見積もりをリクエストする

材料グレードを送信します, 標準, NPS, 圧力クラス, フランジタイプ, 直面している, パイプスケジュール, 数量と検査要件. SASA FLANGE will review the technical description before quotation.

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