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Reference Table Details

Stainless Steel Buttweld Fitting

ASTM A774, ASTM A403



  • Specification covers five grades of stainless
  • Specification covers 3 in. through 48 in.
  • Specification covers wall thickness from .062 - .500
  • Does not require annealing
  • Specification is for low pressure piping and is intended for low and moderate temperatures and general corrosive service.

ASTM A-403

  • Specification covers wrought stainless steel fittings and pressure applications.
  • Specification covers many grades of stainless
  • Two major categories of A-403 fittings:
    • A-403 CR
    • A-403 WP


  • Normally a fabricated fitting rather than formed.
  • Does not require non-destructive testing.
  • Does require annealing.
  • Shall meet requirements of MSS-SP-43


  • Class WP-S: Shall be seamless construction and meet requirements on ANSI B16.9, B16.28.
  • Class WP-W: Any welding done with the addition of filler metal requires X-ray.
  • Class WPW-X: ALL welds must be X-rayed.
  • Class WPW-P: ALL welds must be ultra-sonically examined.


  • WPWBU: Cold formed stub-ends that have weld metal added for dimensional reasons.
  • Stubends with entire lap from from weld metal testing required if marked:
  1. WPW - radiographic inspection of lap is required.
  2. WPWX - Radiographic inspection of all welds is required.
  3. WPWU - Ultrasonic inspection of all welds is required.
  4. CR - Non-destructive examination is not required.

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