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 by open-