Under the API Spec 5L standard, the dimensional accuracy requirements for steel pipe raw materials are as follows:

Outer diameter:

When the outer diameter of the steel pipe is ≥ 60.3mm and the wall thickness S is < 20mm, the allowable deviation is ± 0.75%. For example, for a steel pipe with an outer diameter of 100mm, the allowable deviation range for its outer diameter is 100 × (1 ± 0.75%), which is between 99.25mm and 100.75mm.

When the outer diameter of the steel pipe is ≥ 60.3mm and the wall thickness S is ≥ 20mm, the allowable deviation is ± 1.00%. For steel pipes with an outer diameter of 120mm and a wall thickness of 25mm, the allowable deviation range for the outer diameter is 120 × (1 ± 1.00%), which is between 118.8mm and 121.2mm.

When the outer diameter of the steel pipe is ≤ 73.0mm, the allowable deviation is+15% and -12.5%. Assuming the outer diameter of the steel pipe is 70mm, the maximum allowable outer diameter is 70 × (1+15%)=80.5mm, and the minimum value is 70 × (1-12.5%)=61.25mm.

When the outer diameter of the steel pipe is greater than 73.0mm and the wall thickness S is less than 20mm, the allowable deviation is+15% and -12.5%. For example, for a steel pipe with an outer diameter of 80mm and a wall thickness of 15mm, the maximum allowable outer diameter is 92mm (1+15%) and the minimum value is 70mm (1-12.5%).

When the outer diameter of the steel pipe is greater than 73.0mm and the wall thickness S is ≥ 20mm, the allowable deviation is+17.5% and -10%. If the outer diameter of the steel pipe is 90mm and the wall thickness is 20mm, the maximum allowable outer diameter is 90 × (1+17.5%)=105.75mm, and the minimum value is 90 × (1-10%)=81mm.

Wall thickness: The allowable deviation for wall thickness is usually -3% t~+6% t (t is the wall thickness of the steel pipe), and the average wall thickness is required to be no less than the nominal wall thickness. For example, for a steel pipe with a nominal wall thickness of 10mm, the minimum allowable wall thickness is 10 × (1-3%)=9.7mm, and the maximum value is 10 × (1+6%)=10.6mm. And the average wall thickness at each point on the entire circumference of the steel pipe cannot be less than 10mm.

Non roundness:

The roundness of the pipe end is generally required to be ≤ 1% D. For example, for a steel pipe with an outer diameter of 200mm, the out of roundness of the pipe end should not exceed 200 × 1%=2mm, that is, the difference between the maximum and minimum outer diameters of the pipe end section should not exceed 2mm.

The requirement for the roundness of the pipe body is ≤ 1.2% D. For steel pipes with an outer diameter of 300mm, the out of roundness of the pipe body should not exceed 300 × 1.2%=3.6mm, which means that the difference between the maximum and minimum outer diameters of any section of the pipe body should be less than or equal to 3.6mm.

Length: The standard does not specify a unified requirement for the accuracy of length dimensions, which is usually determined based on actual engineering needs and contract agreements. Common lengths include single random length (SRL), double random length (DRL), 20 feet (approximately 6 meters), 40 feet (approximately 12 meters), etc., and can also be customized according to customer requirements. For example, in some projects, it may be required to control the deviation of steel pipe length within ± 50mm; In other projects, the allowable length deviation may be stricter or looser depending on specific installation requirements.

It should be noted that in practical applications, the specific dimensional accuracy requirements may vary due to special engineering needs, customer specific requirements, as well as factors such as the steel grade of the steel pipe and the usage environment. For example, for steel pipes used in high-pressure and highly corrosive environments, stricter dimensional accuracy may be required to ensure the connection performance and corrosion resistance of the steel pipes.