Seamless pipe refers to a steel pipe made of a single piece of metal without seams on the surface, called seamless steel pipe. According to the production method, seamless pipes are divided into hot-rolled pipes, cold-rolled pipes, cold-drawn pipes, extruded pipes, and pipe jacking. According to the cross-sectional shape, the seamless steel pipe is divided into two types: round and special-shaped. The maximum diameter is 650mm and the minimum diameter is 0.3mm.
Seamless pipe according to GB/T8162-87
1) Seamless pipe specifications: the outer diameter of the hot-rolled tube is 32-630mm, and the wall thickness is 2.5-75mm; the outer diameter of the cold-rolled (cold-drawn) tube is 5-200mm, and the wall thickness is 2.5-12mm.
2) Appearance quality: There should be no cracks, folds, folds, delaminations, hair lines and scarring defects on the inner and outer surfaces of the steel pipe. These defects should be completely removed, and the wall thickness and outer diameter should not exceed negative deviations after removal.
3) Both ends of the steel pipe should be cut at right angles, and the burrs should be removed; the steel pipe with a wall thickness greater than 20mm is allowed to be cut by gas cutting and thermal sawing. After the agreement between the supply and demand sides, the head may not be cut.
4) "Surface Quality" of cold-drawn or cold-rolled precision seamless steel pipe refers to GB3639-83.
1) The domestic seamless pipe supplied according to the performance of the mechanism, the ordinary carbon steel is manufactured according to the class A steel of GB/T700-88 (but it must be ensured that the sulfur content does not exceed 0.050% and the phosphorus content does not exceed 0.045%), and its mechanical The performance should conform to the values specified in the GB8162-87 table.
2) The domestic seamless pipe supplied according to the hydrostatic test must guarantee the hydrostatic test specified in the standard.
3) The physical property inspection of imported seamless pipes shall be carried out according to the relevant standards stipulated in the contract.
China's current seamless pipe standard:
1) Current seamless steel pipe standards: a total of 47 items including: GB/T25 items HB3 items 19 items for special purposes; 2 basic items 45 items
2) Commonly used standards:
① GB/T2102-2018 Acceptance, packaging, marking and quality certificate of steel pipes.
② GB/T17395-2008 Size, shape, weight and allowable deviation of seamless steel pipe.
③ GB/T5310-2018 Seamless steel tubes for high pressure boilers.
④ GB/T9948-2018 Seamless steel pipes for petroleum cracking.
⑤ GB/T6479-2018 Seamless steel pipes for high-pressure fertilizer equipment.
⑥GB/T18248-2018 Seamless steel pipes for gas cylinders.