Ded at the option of the manufacturer. Main steel tube grade: a53-a, a53-b etc. Other grade can also be provided after consulting with acustomers. Permissible variations in weight and dimensions: Weight -- the weight of the pipe as calculated from the relevant equation in asme b36.10m shall not vary by more than 10%. Diameter -- for pipe nps 1 1/2(dn40) and under, the outside diameter at any point shall not vary more than 1/64 in.(0.4mm) from the standard specified. For pipe nps 2 (dn 50) and over, the outside diamter shall not vary more than 1% from the standard specified. Thickness -- the minimum wall thickness at any point shall not more than 12.5% under the nominal wall thickness specified. The minimum wall thickness on inspection shall comform to the requirement. - According to astm a700