Know better about API 5L

API 5L, or the American Petroleum Institute Specification 5L, is a standard for seamless and welded steel pipes used in conveying gas, water, and oil in the petroleum and natural gas industries. It specifies requirements for the manufacture of two product specification levels (PSL1 and PSL2) of seamless and welded steel pipes, detailing chemical composition, mechanical properties, dimensions, testing procedures, and other criteria to ensure quality and performance in pipeline applications.

API 5L COVERS DIFFERENT GRADES OF STEEL PIPES

Grade:

API 5L covers different grades of steel pipe, each of which is assigned a specific grade, such as API 5L Grade B, X42, X46, X52, X56, X60, X65, X70, X80, and others. These grades are defined by their mechanical properties, chemical composition and performance characteristics. The choice of grade depends on factors such as the type of hydrocarbon being transported, operating conditions and environmental considerations.

1. API 5L Grade B:

Application: Suitable for general purpose pipelines in the oil and gas industry.

Mechanical Properties: Minimum yield strength ≥ 245 MPa (35,500 psi) and minimum tensile strength ≥ 415 MPa (60,200 psi).

2. API 5L X42:

 Application: Used for transportation of low and medium pressure natural gas and oil and gas pipelines.

 Mechanical Properties: Minimum yield strength ≥ 290 MPa (42,100 psi), minimum tensile strength ≥ 415 MPa (60,200 psi).

3. API 5L X52:

Application: Suitable for natural gas and oil and gas pipelines carrying medium pressure.

Mechanical Properties: Minimum yield strength ≥360 MPa (52,200 psi), minimum tensile strength ≥460 MPa (66,700 psi).

4. API 5L X60:

Applications: Used for transportation of high pressure natural gas and oil and gas pipelines.

Mechanical Properties: Minimum yield strength ≥415MPa (60,200 psi), minimum tensile strength ≥520MPa (75,400 psi).

5. API 5L X65:

Applications: For high strength, high pressure natural gas and oil and gas pipelines.

Mechanical Properties: Minimum yield strength ≥ 450 MPa (65,300 psi), minimum tensile strength ≥ 535 MPa (77,600 psi).

6. API 5L X70:

Application: For high strength, large diameter natural gas and oil and gas pipelines.

Mechanical Properties: Minimum yield strength ≥ 485 MPa (70,300 psi) and minimum tensile strength ≥ 570 MPa (82,700 psi).

API 5L LINE PIPES INCLUDING TWO LEVES: PSL1 VS PSL2

PSL1 & PSL2

There are two different product specification levels defined in the API 5L standard, namely PSL1 (Product Specification Level 1) and PSL2 (Product Specification Level 2). These two levels have some differences mainly in the manufacturing, chemical composition, mechanical properties, testing and inspection of pipeline steel pipe.

The following are the main differences between API 5L PSL1 and PSL2:

1. Chemical composition:

– PSL1: PSL1 requires a more simplified chemical composition to ensure basic weldability and usability.

– PSL2: PSL2 has more stringent chemical composition requirements and can have higher requirements to improve pipeline properties such as low temperature toughness and corrosion resistance.

2. Mechanical properties:

– PSL1: PSL1 has relatively low requirements for mechanical properties and focuses on basic strength.

– PSL2: PSL2 has higher requirements for mechanical properties, including higher yield strength, tensile strength, impact toughness and hardness indicators.

3. Non-destructive testing:

– PSL1: PSL1 requires non-destructive testing to be limited to eddy current testing.

– PSL2: PSL2 requires more non-destructive testing methods such as ultrasonic testing, magnetic particle testing, X-ray testing, etc. to ensure a higher level of quality control.

4. Impact test:

– PSL1: PSL1 requires impact testing to be performed only at ambient temperature.

– PSL2: PSL2 requires impact testing to be performed at lower temperatures to ensure better low temperature toughness.

5. Welding:

– PSL1: PSL1 pipelines typically have simpler welding requirements.

– PSL2: PSL2 has more stringent welding requirements, including welding process control and weld testing.

The specification also outlines manufacturing processes, inspection procedures and testing requirements to ensure the quality and durability of the pipe. Seamless and welded methods of fabrication are permitted under API 5L, allowing flexibility to meet different project requirements.

API 5L addresses the conditions of use, taking into account factors such as temperature, pressure and environmental factors that the pipe may encounter during its service life. It sets stringent safety and performance standards that provide the foundation for developing pipelines that can withstand the challenges of the oil and gas transportation industry.

In short, API 5L plays a vital role in standardizing steel pipe production and improving pipeline reliability and safety, which is essential for the efficient distribution of hydrocarbons globally.

TEST AND INSPECTION OF API 5L

Hydrostatic Test

A hydrostatic test is a type of pressure test that is commonly used during the production of line pipes. The test is used to check for leaks in the weld seam or pipe body. To conduct the test, water is pumped into the pipe until it reaches a predetermined pressure. The pipe is then monitored for any leaks. If a leak is detected, the pipe will need to be repaired or replaced. The hydrostatic test is an important quality control measure that helps to ensure the safety and integrity of pipes.

Bending Test

A bending test is a type of quality control test that is performed during steel pipe production. The purpose of the test is to check for cracks in the welds, as well as to assess the strength of the steel. To perform the test, a sample piece of pipe is bent into a U-shape. The steel is then examined for cracks or other signs of weakness. If any are found, the entire batch of steel pipes will be scrapped and a new batch will be made. However, if the bending test proves successful, the steel pipes will be approved for use.

Flattening Test

A flattening test is a steel line pipe production test that assesses a steel tube’s resistance to deformation and cracking under stress. It is an important quality control measure that helps ensure the steel used in line pipe products is of the highest possible quality. The test involves applying pressure to a steel tube until it deforms or cracks. The flattening test will reveal the pipe’s resistance to longitudinal and circumferential cracking. The results of the test help determine the steel’s strength and ductility, two important properties for steel used in line pipe applications. Flattening tests are just one of many quality control measures that are used during steel line pipe production, but they play an important role in ensuring the safety and integrity of the final product.

CVN Impact Test

The CVN impact test is a temperature test that is conducted during pipe production in order to ensure the mechanical properties of the pipe. The test is conducted on three different positions on the pipe: the body, the welding seam, and the heat-affected zone. The results of the test are used to determine the Charpy V-notch impact strength of the pipe. The CVN impact test is an important quality control measure for pipe production, and it is required by the American Petroleum Institute (API) in order to meet its standards.

DWTT

The DWTT test, or drop-weight tear tests, are specified in the API 5L production specification. In this test, a large weight is dropped onto a pre-weakened point on a sample of pipe. The resulting fracture is examined to ensure that it meets the requirements for ductile fracture behavior. This test is important because it helps to ensure that pipes will be able to withstand the stress of being transported and installed without breaking. As a result, the DWTT test is an essential part of the quality control process for large diameter line pipes.