Seamless pipe size and allowable deviation:
Deviation grade D1: Standardized outer diameter tolerance ±1.5%, minimum ±0.75 mm
Deviation grade D2: Standardized outer diameter tolerance ±1.0%, minimum ±0.50 mm
Deviation grade D3: Standardized outer diameter tolerance ±0.75%, minimum ±0.30 mm
Deviation grade D4: Standardized outer diameter tolerance ±0.50%, minimum ±0.10 mm
The seamless pipe is made of steel ingot or solid tube blank through perforation to make capillary, and then it is made by hot rolling, cold rolling or cold drawing. Seamless pipe has an important position in my country's steel pipe industry, mainly used as petroleum geological drilling pipe, cracking pipe for petrochemical industry, boiler pipe, bearing pipe and high-precision structural steel pipe for automobiles, tractors and aviation.
Seamless pipes are divided into two categories: hot-rolled and cold-rolled (dial) seamless pipes.
1) Hot-rolled seamless pipes are divided into general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, geological steel pipes and other steel pipes.
2) In addition to general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, and other steel pipes, cold-rolled (dial) seamless pipes also include carbon thin-walled steel pipes, alloy thin-walled steel pipes, etc. Wall steel pipe, stainless thin-walled steel pipe, special-shaped steel pipe. The outer diameter of the hot-rolled seamless pipe is generally greater than 32mm, and the wall thickness is 2.5-75mm. The diameter of the cold-rolled seamless pipe can reach 6mm, and the wall thickness can reach 0.25mm. Cold rolling has higher dimensional accuracy than hot rolling.
The formula for calculating the pressure of seamless pipe:
1) The calculation method of the outer diameter, specification and wall thickness of the cs seamless pipe can withstand the pressure (the tensile strength of different materials of the steel pipe is different) Pressure = (wall thickness * 2 * tensile strength of the steel pipe material) / (outer diameter * coefficient)
2) Calculation method of wall thickness for known cs seamless pipe outer diameter and pressure: Wall thickness = (pressure * outer diameter * coefficient) / (2 * tensile strength of steel pipe material)
3) Representation method of pressure coefficient of cs seamless pipe: steel pipe pressure P17.5 coefficient S=4