API 5L pipe size tolerances

The API 5L standard establishes precise size tolerances to ensure that line pipes meet dimensional accuracy for consistent performance. These tolerances are applied to various dimensions of the pipe, including outside diameter, wall thickness, and length. This article will briefly introduce API 5L pipe size tolerances.

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1. Outside Diameter Tolerance

For pipe diameters ≤ 12 ¾ inches (323.9 mm):
The outside diameter should not deviate by more than ± 0.5% of the specified outside diameter.

For pipe diameters > 12 ¾ inches (323.9 mm):
The deviation should not exceed ± 0.75% of the specified outside diameter.

2. Wall Thickness Tolerance

For pipes of all sizes, the wall thickness shall not be less than 87.5% of the specified nominal thickness, and it shall not exceed 112.5% of the nominal thickness.

3. Pipe Length Tolerance

For single random lengths:
The length of the pipe should be between 16 ft (4.88 m) and 25 ft (7.62 m).

For double random lengths:
The pipe length should be between 35 ft (10.67 m) and 45 ft (13.72 m).

For specific length requirements:
The permissible deviation in length shall not exceed +0.50 inch (+12.7 mm) or -0.25 inch (-6.35 mm) unless otherwise agreed upon.

4. Straightness Tolerance

Pipes must be straight to avoid excessive deviations. The maximum permissible variation is 0.2% of the total length of the pipe.

5. End Squareness

The pipe ends must be cut square to the axis of the pipe, with a maximum deviation of 1/16 inch (1.6 mm) from true square at any point around the circumference.