30 กรกฎาคม 2026

วิธีการตรวจสอบ NDT สำหรับหน้าแปลนเหล็กโลหะผสมฟอร์จ

Technical guideReviewed: 30 กรกฎาคม 2026Prepared by SASA FLANGE Technical Content Team

Direct answer

Forged alloy steel flange inspection can combine visual testing (VT), magnetic-particle testing (มท), liquid-penetrant testing (ปตท) and ultrasonic testing (ยูทาห์). 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.

Key takeaways

  • 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
มท Surface and near-surface discontinuities in ferromagnetic steel Not applicable to austenitic stainless grades
ปตท Surface-breaking discontinuities on nonporous surfaces Does not find buried flaws
ยูทาห์ 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

คำถามที่พบบ่อย

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?

เลขที่. UT examines internal discontinuities; แรงดึง, 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.

Related alloy flange guides

Flange Pmi Testing Flange Hardness Testing F11 F22 F91

Primary standards referenced

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

Request an alloy steel flange quotation

Send the material grade, มาตรฐาน, กรมอุทยานฯ, ระดับความดัน, ประเภทหน้าแปลน, หันหน้าไปทาง, pipe schedule, ข้อกำหนดด้านปริมาณและการตรวจสอบ. SASA FLANGE will review the technical description before quotation.

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