What Is API Steel
API line pipe is steel pipe used for the transmission of oil, gas, and petroleum distillates. Line pipe makes up the pipeline and is different from casing and tubing: casing lines the wellbore, tubing carries produced fluids to the surface, and line pipe transports fluids between facilities over long distances. Line pipes are manufactured according to specifications established by the American Petroleum Institute, principally API 5L.
What Is Line Pipe in the Oil and Gas Industry
Line pipe is used for oil and gas conveyance applications. Manufactured from carbon steel, it transports crude oil, natural gas, production fluids, and water from one point or process to the next. This steel pipe type is durable enough to withstand high pressures, corrosive fluids, and extreme temperatures, and is supplied in seamless and welded forms with grades from low-strength to high-strength microalloyed steels.
The Three Types of Tubing
There are three classes of manufactured tubing: seamless, as-welded or electric resistance welded, and drawn-over-mandrel. Seamless tubing is produced by piercing a solid billet; ERW tubing is formed from strip and welded by resistance heating; and DOM tubing is ERW tube further drawn over a mandrel for improved dimensional accuracy and mechanical properties, used for precision hydraulic and mechanical applications.
What API Means in Piping
API standards are developed for the oil and gas industry and govern the design, manufacture, transportation, and operation of pipes and other equipment used in the production, transportation, and processing of oil and gas. API 5L covers line pipe, API 5CT covers casing and tubing, and API 5DP covers drill pipe, each defining grades, dimensions, testing, and inspection.
Line Pipe Specifications
The pipes are commonly made of steel grades from L245 and L360 to X70, with outer diameters ranging from 60 to 630 mm and wall thicknesses from 1.53 to 40 mm. Production employs microalloying and controlled heat treatment, and high-grade steel products have their performance enhanced by adjusting the carbon equivalent and optimizing heat treatment parameters.
Frequently Asked Questions
Q: What is API steel?
A: Steel pipe manufactured to American Petroleum Institute specifications for oil and gas service, mainly API 5L line pipe.
Q: What is the difference between line pipe and casing?
A: Line pipe transports fluids in pipelines; casing lines and supports the wellbore.
Q: What are the three types of tubing?
A: Seamless, as-welded or ERW, and drawn-over-mandrel.
Q: What grades are common in line pipe?
A: L245, L360, X42 through X70 by strength.
Q: What does API 5L cover?
A: Line pipe grades, dimensions, testing, and inspection for pipeline service.
Q: What is the typical size range?
A: Outer diameters from 60 to 630 mm with wall thicknesses from 1.53 to 40 mm.
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