ASTM A403/A403M

Standard specification covers the standard for wrought for pressure piping applications. ASTM A403 / Standard Specification for Wrought Austenitic Stainless Steel Piping Fittings.

Steel No. Type Chemical composition
C Si S P Mn Cr Ni Mo Other ób ós δ5
WP304 0.08 1 0.03 0.045 2 18-20 8-11 515 205 28
WP304H 0.04-0.1 1 0.03 0.045 2 18-20 8-11 515 205 28
WP304L 0.035 1 0.03 0.045 2 18-20 8-13 485 170 28
WP304LN 0.03 0.75 0.03 0.045 2 18-20 8-10.5 N2:0.1-0.16 515 205 28
WP304N 0.08 0.75 0.03 0.045 2 18-20 8-11 N2:0.1-0.16 550 240 28
WP309 0.15 1 0.03 0.045 2 22-24 12-15 515 205 28
WP310 0.15 1.5 0.03 0.045 2 24-26 19-22 515 205 28
WP316 0.08 1 0.03 0.045 2 16-18 10-14 2-3 515 205 28
WP316H 0.04-0.1 1 0.03 0.045 2 16-18 10-14 2-3 515 205 28
WP316LN 0.03 0.75 0.03 0.045 2 16-18 11-14 2-3 N2:0.1-0.16 515 205 28
WP316L 0.035 1 0.03 0.045 2 16-18 10-16 2-3 485 170 28
WP316N 0.08 0.75 0.03 0.045 2 16-18 11-14 2-3 N2:0.1-0.16 550 240 28
WP317 0.08 1 0.03 0.045 2 18-20 11-15 3-4 515 205 28
WP317L 0.03 1 0.03 0.045 2 18-20 11-15 3-4 515 205 28
WP321 0.08 1 0.03 0.045 2 17-20 9-13 Ti:5C-0.7 515 205 28
WP321H 0.04-0.1 1 0.03 0.045 2 17-20 9-13 Ti:4C-0.7 515 205 28
WP347 0.08 1 0.03 0.045 2 17-20 9-13 Nb+Ta:10C-1.1 515 205 28
WP347H 0.04-0.1 1 0.03 0.045 2 17-20 9-13 Nb+Ta:8C-1 515 205 28
WP348 0.08 1 0.03 0.045 2 17-20 9-13 Ta:0.1 515 205 28
WP348H 0.04-0.1 1 0.03 0.045 2 17-20 9-13 Ta:0.1 515 205 28
Mechanical properties
Tensile and Elongation Requirements WP304, WP316 WP304L, WP316L
Yield Strength, min, ksi [MPa] 30[205] 25[170]
Tensile Strength, min, ksi [MPa] 75[515] 70[485]
Elongation (1) Longitudinal 28 28
Transverse 20 20
General Scope

1.1 This specification covers wrought stainless steel fittings for pressure piping applications.

1.2 Several grades of austenitic stainless steel alloys are included in this specification Grades are designated with a prefix, WP or CR, based on the applicable ASME or MSS dimensional and rating standards, respectively.

1.3 For each of the WP stainless grades, several classes of fittings are covered, to indicate whether seamless or welded construction was utilized. Class designations are also utilized to indicate the nondestructive test method and extent of nondestructive examination (NDE). Table 1 is a general summary of the classes applicable to all WP grades of stainless steel covered by this specification. There are no classes for the CR grades. Specific requirements are covered elsewhere.

1.4 This specification is expressed in both inch-pound units and in SI units. However, unless the order specifies the applicable “M” specification designation (SI units), the material shall be furnished to inch-pound units.

1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.6 This specification does not apply to cast steel fittings. Austenitic stainless steel castings are covered in Specifications A351/A351M, A743/A743M, and A744/A744M.

TABLE 1 Fitting Classes for WP Grades
Class Construction Nondestructive Examination

  • S Seamless None
  • W Welded Radiography or Ultrasonic
  • WX Welded Radiography
  • WU Welded Ultrasonic
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