API 5L line pipe test methods

The API 5L standard outlines a variety of testing methods that are essential for ensuring the performance, quality, and integrity of line pipes. These tests help to confirm that the pipes meet specific requirements for safety and durability. Below is a summary of the key test methods used for API 5L line pipes.

Hydrostatic Test
a. Jointers do not need to undergo a separate hydrostatic test, provided the individual pipe sections used in the jointers have successfully passed hydrostatic testing prior to being joined.
b. In all other cases, the pipe must pass the hydrostatic test without any leakage through either the weld seam or the pipe body.

Bend Test
During the bend test, no cracks should occur in any part of the sample, and the weld should not open. It is important to note that for all bend tests, the weld should extend 6.4 mm (0.25 in) on each side of the fusion line.

Flattening Test
This test verifies the pipe’s deformation performance to a specified size while revealing any internal or surface defects. The test is designed to show the pipe’s resistance to longitudinal and circumferential cracking.

In addition to these three common tests, other required tests include:

- Guided-bend Test

- CVN Impact Test for PSL2 Pipe (covering pipe body, weld, and heat-affected zone)

- DWT Test for PSL2 Welded Pipe

Surface Conditions, Imperfections, and Defects
All API 5L pipes must be free from defects such as cracks, sweats, and leaks. Common surface defects include:

Undercuts in SAW and COW pipes

Arc burns

Laminations

Geometric deviations

Hard spots

For surface imperfections where the defect depth exceeds 0.125 of the wall thickness or is less than or equal to 0.125 of the wall thickness, API 5L Clause C provides additional guidance.