API represents American Petroleum Institute.
API 5l steel pipe means that the pipe must be made according to the standards of this institute. API steel pipe is a kind of line pipe conforming to American oil standard. Line pipe is the process which can transfer the oil, steam, water from the ground to the oil and gas industry enterprises through the pipeline. Line pipe includes seamless pipe and welded steel pipe, and its pipe end incorporates flat end, threaded end and socket end; besides, its connection way is classified into welding tip, coupling connection, socket connection, etc. With the progress of welded pipe forming, the application scope of welded pipe gradually expands. It is in dominance in the line pipe industry, which restricts the development of stainless steel seamless line pipe.
Before presenting the definition of API seamless steel, it is definitely necessary to popularize the knowledge and history of API (American Petroleum Institute). It is the biggest trade association for natural gas and petroleum in America.The main function of API is that it represents this institute to negotiate and propaganda with the government and it can also makes great influence on the issues including the economy and environment and so forth. It will draw up the uniform standards to the oil industry and its main activity is closely linked with the oil and natural gas industry.
API seamless steel tube is strip steel with a hollow section and there are no surrounding joints. The manufacturing process of API seamless steel tube incorporates two types. One is hot rolled (extrusion seamless steel tube). It includes: the circular tube billet - heating - punching - three-roll skew rolling- extrusion- tube off- fixed diameter pipe (or reducing) -cooling tube straightening- hydrostatic test (or inspection) to tags- put in storage. The other type is seamless steel pipe cold drawing (rolling). The process is a round tube billet-heating –punching-heading- annealing-pickling and oil (copper) -multi-channel time cold drawing (cold)- billet tube - heat treatment - straightening to hydrostatic test –marking-storage. What's more, the API seamless steel pipe has many unique features. Firstly, the pipe can be manufactured according to the customer's specific requirement. It means that the tube can be produced with any magnitude and size depending on the demands.
