API 5L Line Pipe


API 5L Line Pipe

API 5L is a standard specification for line pipe that which American Petroleum Institute (API) develops and it provides the requirements for the manufacture of two product levels (PSL1 and PSL2) of seamless and welded steel pipe for the use of the global petroleum industry, especially in the transport of crude oil, natural gas, and water. Licensees need not apply for a license to use this specification outside their direct control. The latest edition of API 5L line pipe standard is the 46th Edition. This standard was first published in the year 1965. The requirement of API 5L standard covers two product levels – PSL 1 and PSL 2, which both specify different technical requirements including chemical, mechanical, hydrostatic testing, etc. Quality requirements are specified at each level i.e. PSL 1 & PSL 2, along with repair methods if required. To get a license to use this standard, line pipe manufacturers or service providers have to meet certain requirements set by American Petroleum Institute (API). They need quality assurance programs and pass audits carried out by API. After that, they will be issued a license that allows them to put the API monogram on their products or services. Licensees are required to renew their license every three years to keep it valid.

Why choose tuspipe?


Since 1998, Tianjin United Steel Pipe Co., Ltd (TUSPIPE) has been committed to supplying high-quality line pipes.

With over 500,000 tons annual production capacity, the company serves various fields and industries, such as oil & gas exploitation and transmission, ship & auto-building, water & electricity, environmental protection, mechanical engineering, infrastructure construction and etc.

TUSPIPE places a premium on product quality and rigorous product quality control. In order to maintain good product quality,  the company has established a Test & Inspection Center since 2004. With a series of state-of-the-art tests and inspection equipment, the test & inspection center is able to perform the tensile tests, hydro tests, impact tests, DWTT, etc.

Play Video about Tianjin United Steel Pipe Co., Ltd office building

Dimensions and Size RANGE of API 5L Line Pipe

Before purchasing an API 5L line pipe, it is important to check the size and dimensions of the line pipe to ensure that it meets the required standards. The dimensions and masses of API 5L line pipes are specified in ISO 4200 and ASME B36.10M. These standards provide a guide for different size pipes and specify the wall thickness of each size. To check if a particular pipe meets the required standards, refer to these tables. Doing so will help to ensure that the pipe is the right size and has the correct wall thickness.

Nominal Pipe Size (NPS)Outside DiameterNominal Wall Thickness
321 1/4″42.21.652.773.564.856.353.584.859.7
401 1/2″48.31.652.773.685.057.143.685.0810.15
652 1/2″732.
903 1/2″

Production Tolerances of API 5L Line Pipe

- API 5L Outside Diameter and Out of Roundness Tolerance

API 5L Line Pipe Tolerance for Diameter and Out-of-roundness

- API 5L Wall Thickness Tolerances

API 5L Line Pipe Tolerances for Wall Thickness

- API 5L Length Tolerances

According to the requirements outlined in API 5L, random lengths of line pipe shall be delivered within the tolerances given below, and approximate lengths must be delivered within ± 500 mm (20 in.). Additionally, if the supply of jointers is agreed upon, jointers comprising two pieces welded together to make a length shorter than 15.0 m (49.2 ft) may be furnished to a maximum of 5 % of the order item, or as agreed. Jointers comprising three pieces welded together to make a length 15.0 m (49.2 ft) or longer may also be furnished for the entire order item or any portion thereof, though this is limited to a maximum of 5 % of the order item as well. These requirements ensure that line pipes are of the correct length and can be properly joined together when necessary.

Tolerances for Random Length API 5L Line Pipe

Steel Grades of API 5L Line Pipe

The American Petroleum Institute’s (API) steel grades for line pipe standardize the chemistry and mechanical properties of the material used to manufacture line pipe. All line pipe produced under an API specification must adhere to the requirements set forth by the standard. The most common grades of API 5L steel are Grades B, X42, X52, X60, and X65. The number that follows the “X” indicates the minimum yield strength of the pipe in thousands of pounds per square inch (PSI). For example, X42 line pipe must have a minimum yield strength of 42,000 PSI. Line pipe is most frequently used in oil and gas transportation applications. However, it can also be used for water transport, building construction, and other industrial applications. Steel grades are an important part of understanding line pipe performance and selecting the right material for a specific application.

There are multiple grades of API 5L steel available, each with different yield strength and tensile strength ratings. The most common grades for line pipes are:
* Grade X52 – has a minimum yield strength of 52 ksi (365 MPa) and a minimum ultimate tensile strength of 66 ksi (460 MPa)
* Grade X56 – has a minimum yield strength of 56 ksi (390 MPa) and a minimum ultimate tensile strength of 71 ksi (490 MPa)
* Grade X60 – has a minimum yield strength of 60 ksi (415 MPa) and a minimum ultimate tensile strength of 75 ksi (515 MPa)
* Grade X65 – has a minimum yield strength of 65 ksi (450 MPa) and a minimum ultimate tensile strength of 77 ksi (525 MPa).
Pipelines transporting categories A, B, or X fluids must be constructed from steel materials that have an area under the stress-strain curve that meets the requirements specified in the material standard. The specified minimum yield and tensile strengths “represent the point on the Stress

Test and inspection of API 5L Line pipes

- 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.


The DWTT test, or drop-weight tear tests, are specified in the API 5L pipeline 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.

Inspection Frequency for API 5L Line Pipes

- Inspection Frequency for API 5L PSL 1 Line Pipe

Inspection Frequency for API 5L PSL 1 Line Pipe

- Inspection Frequency for API 5L PSL 2 Line Pipe

Inspection Frequency for API 5L PSL 2 Line Pipe

How to Select an API 5L Certified Line Pipe Supplier in China?

When selecting an API 5L certified supplier in China, it is important to be aware of the fake certificates that some companies use. These fake certificates are often created using photoshop and can be very difficult to identify. However, they can often trick buyers into thinking they are getting a high-quality product when in reality the product is of low quality and may even be dangerous. This damages the projects that use these pipes because they are not up to code and they can cause safety issues. If something goes wrong, the company that chose the line pipe supplier with a fake certificate can be sued and lose a lot of money in compensation payments. Don’t let this happen to your company! As such, it is always best to select a reputable and trustworthy supplier who can provide you quality pipes with a genuine API 5L certificate. This will help to ensure the safety of your business and avoid any potential legal problems. Next, I’ll show you how to spot fake certificates.

1. Check the API Composite List


The Composite List is a directory of all the companies that are certified by the American Petroleum Institute (API). This list can be used to check if a line pipe manufacturer is authorized to use the API logo on its products. To search the Composite List, 

1) Go to the API official website and find the “API Composite List” tab;

2) You will see the screenshot above, type in the company name or certification number, and click “Search”;

3) Finally, you will see the company detail about the certification types and the certification status. 

If the certification type is what you are looking for, and the certificate status also shows “Active”, then you are safe at this stage. While you may also interested in checking the company details to see if you are dealing with the right person, you can click on the company name shown in red.

2. Check the Non-Licensee / Registrant List


The American Petroleum Institute (API) also released a list showing all the cheater companies that API has found in the past, and these companies are still in the market. The API Non-Licensee/Registrant List is a great resource for finding unqualified suppliers who are holding fake certificates. Here is how to check the list:

1) Go to the API official website and find the “Non-Licensee/Registrant List” tab;

2) Scroll down to find all the cheater companies who may want to fool you with a fake license.

You can use this information to help you narrow down your search for a qualified line pipe supplier. If you are looking for a specific company, you can type the company name in the “Search” box.

3. Check the MTC from the Supplier


Even if you don’t find anything unusual in the above steps, it doesn’t mean your supplier is qualified. I suggest you check its MTC in the next step. I know an MTC is easy to be “cloned”, but you may still find some weak points in it.

1) The company name – as you can see in the above picture, the name is very similar to our company name, but they are absolutely different. On a real certificate, the “Co.” would never be written as “Company”, and the “Ltd” would never be written as “Limited”.

2) The CNAS certification – CNAS is an organization that evaluates whether a lab can be accredited to National Accredited Testing Laboratory in China. It has bilateral or multi-lateral accreditation cooperation agreements with relevant accreditation organizations around the world. So we can check this certificate also to eliminate our doubts. First, go to the CNAS official website; Second, click on “Find an Accredited Body“; Then, choose “Testing & Calibration Laboratories“, and type in the registration number or the company name; Finally, you can check if the registration number and company name are matched to the MTC you have;

3) The API certification number – Usually, a line pipe mill that is holding the API certification would show the certification numbers on the MTC. While there is none of it on the sample MTC above.

Slotted Liner
Steel Fabrication
Pipe Fittings
Scroll to Top

Get A Quote Now

Fill in the form below and our team will be happy to assist you