The Grading of API Steel Pipe

The time of issue:2014-3-21 10:51:59       Author:

In general, API steel pipe can be graded on the basis of ASTM (American Society for Testing Materials) standards and ASME standards. ASTM is a prestigious global organization that has been devoted to the development of industry standards. ASME standards roughly cover a wide range of materials that are manufactured and used in construction projects or various industries. ASTM is a voluntary standards development company is wholly independent of any manufacturers. As a matter of fact, ASTM International is the company that issues the industry standards for most of the steel pipe manufacturers. ASME standards of API steel pipe can be either downloaded or purchased from ASTM website and several other websites that host the documentation of ASME standards.

There are a vast number of steel pipes produced in the piping industry. For example, some of the commonly seen steel pipes are API steel pipe, seamless steel pipe, welded steel pipe, and black steel pipe. What is more, there are a lot of subcategories for each type of steel pipe. For instance under the category of welded steel pipe, there are ERW welded steel pipe, single welded pipe, continuously welded pipes, etc. And while some low carbon steel pipes can be used in the oil and gas industries some other pipes cannot. Therefore, ASME standards of each steel pipe are based on its specific manufacturing process, raw materials and production techniques. The manufacture and installation of API steel pipe is tightly regulated by the ASME standards. In fact, ASME standards have the force of law in such countries as Canada and the USA and are also recognized in many European countries and African nations. To ensure the high quality of the piping products, the manufacture, storage, testing, etc. of API steel pipe must meet stringent quality ASME standards. What is more, manufacturing standards for API steel pipe commonly require a test of chemical composition and a series of mechanical strength tests.

Pressure and wall thickness are among the major criteria in grading API steel pipe. In general, API steel pipe is graded is strength in terms of pressure and there are many grades of API steel pipe for each standard ASTM Code. The code refers to a minimum yield strength and minimum tensile strength of API steel pipe and there are grades ranging from grade 1, grade 2, grade A, grade B, to grade X. Each grade of API steel pipe has a minimum and maximum pressure rating. For example, with grade 1 ASTM 658 API steel pipe, the minimum yield strength is 400000 PSI and minimum tensile strength is 60,000 PSI. In addition, the wall thickness of API steel pipe is especially important because API steel pipe with too thin a wall may burst under pressure.

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