Specification ASTM A234 WPB / ASME B16.9 Connections

ASTM A234 WPB fitting is the standard specification for carbon steel pipe fittings and forged steel alloys for moderate and high temperature service.

This specification covers seamless and welded construction carbon steel and forged steel fittings. These fittings are for use in pressure piping and in the manufacture of pressure vessels for moderate to high temperature service.

The material for fittings shall consist of forged steel, bars, plates, seamless tubing or fusion welded with the addition of filler metal. Forging or shaping operations can be performed by hammering, pressing, drilling, extruding, twisting, rolling, bending, melting welding, machining, or by combining two or more of these operations.

The shaping procedure must be applied in such a way that it does not produce harmful imperfections in the fittings. Accessories, after formation at a high temperature, should be cooled to a temperature below the critical range under appropriate conditions to avoid harmful defects caused by very rapid cooling, but in no case faster than the cooling rate in still air.

Accessories must be subjected to stress testing, hardness testing and hydrostatic testing.

Chemical Composition (%) ASTM A234 WPB Connections

WPB0,30,29 - 1,060,050,0580,1 min0,40,40,40,40,080,02
WPC0,350,29 - 1,060,050,0580,1 min0,40,40,40,40,080,02
WP11 CL10,05 - 0,150,30 - 0,600,030,030,50 - 1,000,44 - 0,65-----
WP 11 CL2 / 30,05 - 0,200,30 - 0,800,040,040,50 - 1,000,44 - 0,65-----


  1. For each 0.01% reduction below the specified maximum C, an increase of 0.06% Mn above the specified maximum will be allowed, up to a maximum of 1.35%.
  2. The sum of Cu, Ni, Cr and Mo should not exceed 1.00%.
  3. The sum of Cr and Mo should not exceed 0.32%.
  4. Maximum carbon equivalent (EC) should be 0.50 based on heat analysis and formula CE = C + Mn / 6 + (Cr + Mo + V) / 5 + (Ni + Cu) / 15

Mechanical Properties of ASTM A234 WPB Connection

Traction RequirementsWPBWPC, WP11CL2WP11CL11WP11CL3
Tensile strength, min, ksi [M Pa]60-8570-9560-8575 a 100
(0.2% offset or 0.5% extension under load)[415-585][485-655][415-585][520-690]
Yield strength, min, ksi [M Pa]32403045

What is the manufacturing process for ASTM A234 WPB pipe fittings?

It is simply an identifier developed by ASTM.

The fittings in question are manufactured in the same manner as the auxiliary hose for this specification.

In very large sizes, accessories can be manufactured in pieces and welded together, as is the case with many large accessories.

Is the term used for manufacturing called? forged? which means it is worked as opposed to being molded or forged.

As for standing W for weldable, I am not sure that it is correct as there are many, many pipe fittings that are weldable but have different designations of W. Note the reference below.

Forging is the process of manufacturing ASTM A234 WPB pipe fittings.

  • W = WELDÁVEL / wrought
  • The most recent default is: ASTM A234 / A234M-07

Standard Specification for Forged Carbon Steel and Alloy Steel Pipe Fittings for Moderate and High Temperature Service.

This standard covers seamless and welded forged carbon steel fittings that are fabricated to ASME B16.9 and B16.28 dimensional specifications.

These fittings are primarily for use in pressure piping and in the manufacture of pressure vessels for moderate and high temperature service.

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