①For product (steel pipe) level PSL1：For each reduction of 0.01 % below the specified maximum concentration for carbon, an increase of 0.05 % above the specified maximum concentration for Mn is permissible, up to a maximum of 1 .65 % for grades ≥ L245 or B, but ≤ L360 or X52; up to a maximum of 1.75 % for grades > L360 or X52, but < L485 or X70; and up to a maximum of 2.00 % for Grade L485 or X70.
②For product (steel pipe) level PSL2：For each reduction of 0.01 % below the specified maximum for C, an increase of 0.05 % above the specified maximum for Mn is permissible, up to a maximum of 1.65 % for grades ≥ L245 or B, but ≤ L360 or X52; up to a maximum of 1.75 % for grades > L360 or X52, but < L485 or X70; up to a maximum of 2.00 % for grades ≥ L485 or X70, but ≤ L555 or X80; and up to a maximum of 2.20 % for grades > L555 or X80.

*The calculation formula of minimum elongation：δ=C×(A^0.2 / U^0.9)
where
C is 1940 for calculations using SI units and 625,000 for calculations using USC units;
A is the applicable tensile test piece cross-sectional area, expressed in square millimeters (square inches), as follows:
ⓐ for circular cross-section test pieces, 130 mm² (0.20 in. ² ) for 12.7 mm (0.500 in.) and 8.9 mm (0.350 in.) diameter test pieces; 65 mm² (0.1 0 in. ² ) for 6.4 mm (0.250 in.) diameter test pieces;
ⓑ for full-section test pieces, the lesser of a) 485 mm² (0.75 in.² ) and b) the cross-sectional area of the test piece, derived using the specified outside diameter and the specified wall thickness of the pipe, rounded to the nearest 10 mm² (0.01 in. ² );
ⓒ for strip test pieces, the lesser of a) 485 mm² (0.75 in. 2 ) and b) the cross-sectional area of the test piece, derived using the specified width of the test piece and the specified wall thickness of the pipe, rounded to the nearest 10 mm² (0.01 in.² );
ⓓ U is the specified minimum tensile strength, expressed in megapascals (pounds per square inch).