What is the usual tolerance for wall thickness in seamless steel pipes?

In accordance with the National Standard: GB/T8162-2008, the rules for the National Standard on Seamless Steel Tubes for Structural Use are as follows:

Defects with a wall thickness of less than 3 millimeters are within ±15%S/±10%S or ±0.15, whichever is greater.

Wall thickness error of ±12.5%S to -10%S for 3~10mm thickness

Wall thicknesses exceeding 10 millimeters are allowed to have a tolerance of ±10%S.

Nominal wall thickness for steel pipes is S, other specifications are subject to negotiation between both parties and must be noted in the contract. Steel pipes with dimensions outside the specified rules may have allowable tolerance errors.

Based on the above Seamless Steel Pipe Wall Thickness Allowable Deviation National Standard, for example:

Wall thickness tolerance for 25*5 seamless steel pipes is 0.5-0.625mm.

What are the impacts of uneven wall thickness in eccentric seamless steel tubes?

Inconsistent thickness can impact production costs. In the application fields of precision machinery and hydraulic pipes, wall thickness deviation is a crucial target. As the eccentricity of seamless steel pipes involves processing volume, the size of processing volume directly affects production costs. Excessive eccentricity makes it impossible to achieve the finished product size required by the customer, leading to the entire batch of seamless steel pipes becoming scrap. This not only increases the customer's production costs but also causes delays in delivery. Therefore, customers with wall thickness requirements should pay special attention to the detection of wall thickness deviation when purchasing seamless steel pipes.