SEAMLESS PIPE



ASTM pipe specifications

  • ASTM A53, A106, A333, and API 5L (types of carbon steel pipes for high and low-temperature carbon steel)
  • ASTM A335 Grades P5 to P91 (chrome-moly alloy steel pipes for high temperature and pressure, for refinery and power plants applications)
  • ASTM A312 Series 300 and 400 (stainless steel pipes in grades 304, 316, 321, 347)
  • ASTM A790/A928 (duplex and super duplex pipes with double ferritic and austenitic structure)
  • Various nickel alloys material specifications (Inconel, Hastelloy, Cupronickel, Monel, Nickel 200)
  • Specifications for non-ferrous pipes (aluminum, copper, brass, cupro-nickel)


SEAMLESS PIPE SIZES

The ASME B36.10 and B36.19 specifications cover the dimensions and weights of seamless pipes for the petrochemical industry (the specs apply to welded pipes too):

  • The ASME B36.10 specification covers carbon and low-alloy seamless pipes sizes (dimensions and weights) between 1/8 and 24 inches
  • The ASME B36.19 specification, instead, covers the dimensions and weights of stainless steel, duplex, nickel-alloy seamless pipes

Commercial seamless pipes are designated with a nominal pipe size (representing the approximate fluid conveyance capacity of the pipe) and with a “schedule”, which refers to the thickness of the pipe (the most common are schedule 40, STD, XS, XXS for carbon/alloy pipes, and 10S, 40S and 80S for stainless and nickel alloy pipes).

 

ERW PIPE (ELECTRIC RESISTANCE WELDING)


ERW pipes are manufactured using steel coils: the coil is first uncoiled, then smoothed, cut and, finally formed into a pipe shape by joining its two extremities electrically.

ERW pipes are available in sizes between 1/2 and 20 inches, in carbon steel (ASTM A53 is the most common specification) and stainless steel (ASTM A312). In terms of dimensions, the ASME B36.10 and ASME B36.19 are the key reference specifications (API 5L for welded ERW line pipes).

The ASME and API dimensional charts show typical combinations of pipe nominal size and wall thickness (designated as “schedule”), and show ERW pipe weight in kg (or pounds).

In the last few years, ERW pipes are have become an efficient alternative to seamless pipes, both in terms of price and performance, due to the modern welding technologies adopted by ERW pipe manufacturers (example HFI and HFW, high-frequency welding). These advancements in welding technologies have reduced, over time, the technical superiority of seamless pipes vs ERW pipes, making them interchangeable at least in some applications (low/medium pressure and temperature). Of course, seamless pipes will always benefit from the intrinsic superior mechanical strength of steel billets vs. coils and plates.



LSAW PIPE (LONGITUDINAL SUBMERGED ARC WELDING)


An LSAW pipe (“submerged arc welding”) is manufactured by cutting, bending and welding steel plates (JCOE process).

LSAW pipes compete with seamless and ERW pipes in the size range between 16 and 24 inches but are “must-go” option for pipelines above 24 inches (as 24 inches is the maximum size for commercial seamless pipes).

The two main types of LSAW pipes are the longitudinal (with a single or double straight seam weld, DSAW) and the spiral type (called, HSAW, SSAW or SAWL pipe). Therefore, the difference between DSAW vs. LSAW is that DSAW pipes have a seam weld in the inside and outside of the pipe, whereas LSAW pipes have a single seam weld on the outer surface.

The difference between LSAW and ERW pipes is that LSAW pipes are produced using steel plates, ERW pipes are manufactured starting from steel coils.

In the oil and gas industry, large diameter API 5L LSAW pipes are used to transport hydrocarbons over long distances efficiently.

HSAW/SSAW spiral weld pipes are used for non-critical applications, as water transmission and distribution (not for oil & gas).