11 Years Factory wholesale Stainless Steel for Madrid Importers

Carbon Steel Pipe Production.

Carbon Steel Pipe

The term carbon steel pipe is quite broad in scope and can be used to describe a wide range of metal tubular goods whose main alloying element is carbon. Although many of the same manufacturing principles apply to both carbon steel pipe and various similar alloy tubular goods, the focus of this narrative will be on the manufacturing process of mild carbon steel pipe goods commonly used for oil and gas as well as water transmission, structural applications, general purpose casing, piling, and mechanical components.

Carbon steel pipe starts out by arriving at the pipe mill in the form of either a billet (basically a large solid steel bar) or a coil (imagine a roll of toilet paper made out of steel). Depending on the manufacturing method used by the mill, these billets or coils will be processed to yield the finished end product. We will examine the various manufacturing methods used to make carbon steel pipe, but first let’s look at how the carbon steel got here in the first place.

SEAMLESS CARBON STEEL PIPE

Seamless carbon steel pipe has, as its name implies, no longitudinal weld seam. It is, in essence, one solid homogeneous piece of steel. A solid billet is simply heated and then stretched over a series of mandrels until the pipe has achieved its desired diameter and wall thickness. Typically seamless carbon steel pipe fourteen inches and greater in diameter are rolled from shells which expand the diameter and reduce the wall until the desired dimensions are achieved. Sizes smaller than fourteen inches in diameter are typically stretch reduced whereby the diameter is gradually reduced and the wall relatively increased via a series of rolls. There is also a cold forming process for seamless pipe production, but such manufacturing processes are typically reserved for different alloys. Being that there is no seam, seamless carbon steel pipe is typically used in high pressure applications. Common seamless specs include; API5LB, A106, A333

DOUBLE SUBMERGED ARC WELD (DSAW)

The double submerged arc weld (DSAW) process is similar to that of the ERW process in that coils of carbon steel are unrolled in a continuous ribbon. As the DSAW method of manufacturing is typically used for larger diameter pipe, the method of roll forming the skelp is similar to but not exactly like that of ERW. DSAW pipe is typically either pyramid rolled (three angled OD rolls in the shape of a pyramid form the pipe) or rolled using the U-O-E process (skelp is first subject to a “U” shaped press, followed by a “O” shaped press). The most prominent difference between ERW and DSAW carbon steel pipe is the longitudinal weld. The DSAW arc weld is submerged in a flux media to keep the weld from being exposed to ambient contaminants. Also, both the OD and the ID of the pipe is welded, typically at separate times creating a situation where one weld consumes the other creating a higher quality weld. DSAW carbon steel pipe is easily distinguishable due to its prominent and consistent ID and OD weld seam. Common DSAW specs include; API5l, A252, and A139.

SPIRAL WELD

The most easily distinguishable manufacturing method for carbon steel pipe is spiral weld. In this process the weld is created in the exact same manner as that of DSAW, only the weld seam takes on a helical or spiral appearance due to the way the skelp is rolled to form. Just as in the case with the ERW and DSAW process, a continuous ribbon of skelp is leveled and sent through a series of rolls to form. In the case of the spiral weld process a simple three roll bend is typical and thus makes for faster, more efficient, and less costly manufacturing process. The spiral weld process also allows the mill to roll a much wider range of sizes than DSAW or ERW mills. Also, due to its axial symmetry, spiral weld carbon steel pipe has an inherent ability to maintain straightness. Common spiral weld specs include; API5LB and A252.