Pressure withstandable for 219*40 seamless steel pipe: P=(2*_/S*delta)/D = (2*410/4*40)/219 = 37.5 MPa. The tensile strength of the material is_, the pressure is P, the outer diameter of the tube is D, and the wall thickness of the tube is delta. S is safety factor; pressure P is less than 7 MPa, S = 8; P is 7 to 17.5 MPa, S = 6; P is more than 17.5 MPa, S = 4. So 20     

1.1 The nominal outer diameter and wall thickness of steel pipe are 88.9 mm and 6.45 mm respectively. 1.2 The allowable deviation of the outer diameter and wall thickness of the steel tube shall be in accordance with Table 1. The allowable deviation of outer diameter + 0.50mm-0.20mm wall thickness + 0.97mm-0.77mm 2 steel pipe is 9400mm-9750mm in length. 3. The bending degree of the 3.1 shape steel tube shall not be greater than 1.0 m m/m. 3.2 The ends of the steel tube should be perpendicular to the axis of the steel tube, and the burrs in the incisions should be removed. 4. Heavy steel pipes can be delivered by actual weight or theoretical weight. The theoretical weight of steel pipe per meter is 13.115 kg/m. 5. The allowable deviation of the chemical composition of the finished steel tube shall comply with the relevant regulations of GB/T 222. 6. Delivery of steel pipes in hot-rolled condition. 7. After proper heat treatment, the mechanical properties of steel pipes should meet the requirements of N80 grade in API SPEC 5CT. 8. Eddy current testing should be carried out one by one to test the compactness of the steel tube. The diameter of the through hole of the artificial defect of the contrast sample by eddy current testing is 2.2 mm (+0.01 mm). As an important part of iron and steel products, steel pipes can be divided into seamless steel pipes (round billets) and welded steel pipes (slabs, strips) because of their different manufacturing processes and shapes.