Seamless steel pipe
Seamless steel pipes are produced starting from steel billets, that are heated and perforated to create the tubular section. The word "seamless" means the absence of seam welds.
upstream operations (OCTG pipes)
midstream (transmission and distribution of fluids, as oil, gas, steam, acids, slurries)
downstream (process piping to refine oil and gas in derivative products)
general plumbing applications for utility services
The most common types of pipes used in the oil&gas industry are (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)
Some specifications cover Seamless steel pipes only (example ASTM A106), others apply both to seamless and welded pipes (example ASTM A53).
Carbon steel pipes (A53, A333, A106 and API 5L) have the largest market share, as they can be used for most high and low-temperature applications; the main application of stainless steel pipes is for corrosive services (and higher grades are used as the temperature and the pressure increase, or when the conveyed fluid is more and more aggressive).
In the upstream oil & gas industry, API 5CT is the key specification covering OCTG pipes (oil country tubular goods).
Seamless steel pipe
Seamless steel pipes
shall not be confused with seamless tubes. Indeed, there are a few important differences between pipes and tubes, which are not only semantic. In general, the word "pipe" applies to any tubular used to convey fluids, whereas the word "tube" applies to tubular sections (of various shapes, round, oval, squared) used for structural/mechanical applications, instrumentation systems, and the construction of pressure equipment like boilers, heat exchangers, and superheaters.
Seamless steel pipe price
Seamless steel pipes have a higher price per ton than ERW pipes, generally 20 to 30% higher, due to their fairly complex production process (more articulated than the manufacturing process of ERW and LSAW pipes) and to due to the fact that the number of Seamless steel pipe manufacturers is rather limited (the market has an oligopolistic nature).
For specific sizes and specifications (for example a 20-inch pipe or a high wall thickness pipe in special or exotic materials, for example, ASTM A335 P91 pipes), there are few global pipe suppliers and prices per ton (or per meter) are, as a consequence, impacted.
Due to this fact, it is a wrong practice to estimate pipe prices using a standard price per ton for all "carbon steel" or "stainless steel" pipes, regardless the actual diameter, wall thickness, and specific grade: all these factors shall be taken into consideration to prevent cost overruns during the execution of the project at a later stage. Moreover, prices fluctuate daily (especially for alloyed pipes, which contain chemical elements like Molybdenum, Nickel, Copper, Chromium traded daily on the London Metal Exchange or the Ferro-Alloy markets).
Seamless steel pipe SIZES
The ASME B36.10 and B36.19 specifications cover the dimensions and weights of Seamless steel pipes for the petrochemical industry (the specs apply to welded pipes too):
The ASME B36.10 specification covers carbon and low-alloy Seamless steel 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 and welded pipes
Commercial Seamless steel 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).
The ASME pipe size specifications can be purchased online from the ASME website or from the IHS online store.
Seamless steel pipes manufacturing process
Mild steel Seamless steel pipes from 1/8 to 6 inch. are manufactured with the so-called "plug mill process" or the "extrusion process" (used for smaller diameters), whereas the "mandrel mill process" is used for larger diameters.