The process of A234 WPB pipe fittings manufacturing is called “wrought” which means it could be casted or forged. Usually the ASTM A234 WPB elbows , tees, reducers are made from steel pipes,the caps are made from plates. But the large sizes pipe fittings are commonly manufactured in pieces and welded together . ASTM A234 is standard of the pipe fitting material. However, this is indicating the properties of the material of various kinds of alloy steel and carbon steel. WPB is a steel grade in which W stands for weldable, B is grading B and P stands for pressure. Thus it is referring  minimum yield strength . What is ASTM A234 WPB ASTM A234 is Standard Specification for steel pipe fittings includes carbon and alloy steel material for moderate and high temperature services. It covers steel fittings of seamless and welded types. Steel Pipe fittings are applied in pressure pipelines and in pressure vessel fabrications. These fittings material consist of killed steel, forgings,...

ASTM A420/A420M-07 Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Low-Temperature Service. ASTM A420 WPL6 Grade is associated with ASTM A420 for pipe fittings manufactured of Wrought Carbon Steel. WPL6 is a normalized grade of carbon steel that has been Charpy Impact tested at -50 degree F for use in low temperature service. See Also ASTM A333 Grades 1 and 6 (for pipe) and A350 LF2 for flanges. ASTM A420 WPL6 Elbow after complete quality and performance measure inspection. These are widely appreciated for excellent quality, corrosion abrasion and high tensile strength with long life service. ASTM A420 WPL6 Elbow after complete quality and performance measure inspection. These are widely appreciated for excellent quality, corrosion abrasion and high tensile strength with long life service. Materials shall consist of forgings, bars, plates, seamless or fusion welded tubular products with filler metal added, and shall be produced...

The WPB is not short hand for any process. It is simply an identifier developed by ASTM. The fittings in question are manufactured in the same manner as the companion pipe for this specification. ASTM A234 WPB pipe fittings In very large sizes, the fittings may be manufactured in pieces and welded together as is the case for many large fittings. The term used for the manufacturing is called “wrought” which means it is worked as opposed to being cast or forged. As to the W standing for weldable, I’m not sure that is correct since that are many, many pipe fittings that are weldable but carry designations other than a W. Note the reference below. Forging is the manufacturing process of ASTM A234 WPB pipe fittings. W = WELDABLE / wrought P = RELATED TO P NUMBER OF ALLOY MATERIAL B = REFER TO MINIMUM YIELD OF MATERIAL LATEST STANDARD IS: ASTM A234/A234M-07 Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature...