ASTM A350 Gr. LF3 Flanges

Pipe flanges made from ASTM A350 Grade LF3 are generally used in low temperature services with notch toughness testing requirements. The ASTM A350 Grade LF3 refers to a low-alloy steel designated as “3.5% nickel steel” or “3.5-Ni steel”. The deliberately controlled addition of nickel content can reduce the brittle-ductile transition temperature, whereupon improve its low temperature notch toughness significantly. The flanges may be manufactured in accordance with ASME B16.5 or ASME B16.47, or custom-designed.

Pressure-Temperature Ratings

The pressure-temperature ratings of ASTM A350 Gr. LF3 flanges are the same as that of ASTM A105 flanges. The pressure-temperature ratings of 3.5Ni-steel flanges are provided in Tables 1-1 & 1-2 in bar and °C units, while those in Tables 2-1 & 2-2 are provided in psi and °F units.

Chemical Composition Requirements

Tensile Properties at Room Temperature

Charpy V-Notch Impact Test

Flanges made from ASTM A350 LF3 Class 1 or Class 2 shall take the Charpy V-notch impact test at a standard testing temperature of -150°F [-101°C]. The specimens shall be prepared in three pieces in size of 10 by 10 mm with the same heat number of the flange. The minimum impact energy required for average of each set of three specimens shall be 15 ft*lbf [20 J] for Class 1 and 20 ft*lbf [27 J] for Class 2; The minimum impact energy required for each one specimen only is 12 ft*lbf [16J] for Class 1 and 15 ft*lbf [20 J] for Class 2.