Seamless steel pipes are a wide cross section and each sides of the expansion of a resistance to air, water, steam or other weak corrosive media and acid, alkali, salt or other chemical corrosion medium corrosion. They are also known as acid resistant stainless steels.
Seamless Pipes are formed by a forcing molten metal through a round die with a plug mill in the center to form the long tube of continuous metal which is cut into needed lengths; generally either 21 ft. or 40 ft. or other lengths. Seamless Pipes are more uniform in consistency unlike rolled or seamless pipes can also withstand higher operating temperatures and pressures unlike welded pipes like welded with high frequency electric resistance welding.
The seamless carbon steel pipes are formed by perforating steel ingots or solid tube blanks, then hot, cold rolled or drawn. From the caliber, < φ 76, accounting to 35 %, < φ 159 – 650, accounting for 25 %. In terms of varieties, general – purpose of pipes are 1.9 million tons, accounting to 54 %, oil gas pipes are 760,000 tons, accounting to 5.7 %, hydraulic props and precision pipes are 150,000 tons, accounting to 4.3 %, stainless steel pipes, bearing pipes and automobile pipes are 50,000 tons, accounting to 1.4 %.
Seamless carbon steel pipe’s specifications and classifications
Specifications of seamless steel pipes are according to the outer diameters or wall thicknesses in millimeters.
Classification of seamless carbon steel pipes are divided into hot and cold rolled seamless steel pipes.
Hot rolled seamless steel pipes are divided into the general, low and medium – high pressure boiler, alloy, stainless steel pipes, petroleum cracking, geological steel pipes and others.
Cold rolled seamless steel pipes in addition to the general type steel pipes, low, medium and high pressure boiler pipe, alloy and stainless steel pipe, petroleum cracking pipe, others, also includes carbon, alloy, stainless thin walled steel pipe and special shaped steel pipes without welding erw unlike welded pipe like welded seam with electric resistance welding. Even, the welding technology is very improved, pipe suppliers should answer to the users’ needs. Outer diameter of hot rolled seamless pipe is usually larger than 32 mm, the wall thickness is 2.5 mm – 75 mm, the diameter of cold rolled seamless steel pipe can reach to 6 mm, the wall thickness can reach to 0.25 mm, the outer diameter of thin walled pipe can reach to 5 mm, and the wall thickness is less than 0.25 mm.
General seamless carbon steel pipe is made of high alloy carbon steels such as 16Mn, 5MnV, 10, 20, 30, 35, 45, or hot or cold rolled alloy 40Cr, 30CrMnSi, 45Mn2, 40MnB etc. Low carbon seamless steel pipes such as 10 and 20 are mainly used for fluid conveying. 45, 40Cr and other medium carbon steel seamless pipe manufacturer makes them to be used to make mechanical parts.
Low and medium pressure boiler seamless steel pipes are used in the pipe manufacturer of various low and medium pressure boilers, boiling water erw pipes, superheated steam pipes, water wall pipes and superheated steam pipes, large smoke pipes, small smoke pipes and arch brick pipes. Hot or cold rolled manufacturing process seamless steel pipes tubes are made of high quality carbon structural steel. Manufacturers of seamless pipes use mainly made of mild steel No. 10 and 20.
High pressure steel pipes’ for boilers are high quality carbon structural steels, alloy structural steels and stainless heat resistant seamless steel pipes are mainly used as steam boiler pipes for high pressures and above. These boiler pipes are often operated with high temperatures and pressures. Therefore, the steel pipes are required to have high durability, high oxidation resistance and good structural applications stability. The steel grade is high quality carbon structure. Steel has 20G, 20MnG, 25MnG alloy structural steels No. 12CrMoG, 15CrMoG, 12Cr2MoG, 12CrMoVG, 12Cr3MoVSiTiB, 15MoG, 20MoG, etc. rust, heat resistant steels are commonly used 1Cr18Ni9, 1Cr18Ni11Nb high pressure boiler tube to ensure chemical composition and mechanical properties which is necessary to do a hydraulic test one, and to make the flaring and flattening test.
Seamless steel pipe for oil and geological drilling wells for drilling underground structures, oil, groundwater, natural gas and mineral resources. Seamless steel pipes for oil drilling and geological drilling are the main equipment for drilling, mainly including core outer, inner tubes, casings and drill pipes. Mandatory sufficient strength, hardness, wear resistance and impact toughness, steel for steel pipe with DZ plus number one for steel yield point, commonly used steel number DZ45 45MnB, 50Mn; 40Mn2, 40Mn2Si of DZ50; 40Mn2Mo, 40MnVB of DZ55; 40MnMoB of DZ60, 27MnMoVB of DZ65.
Petroleum cracking tubes are seamless tubes for furnace tubes, heat exchanger tubes and pipes used in petroleum refineries. It is made of high quality carbon steel pipe, alloy steel, heat resistant steel, stainless steel. In addition to the chemical compositions and various mechanical properties, the steel pipes must also ensure water pressure, flattening, flaring and other tests like surface quality and nondestructive testing.
Stainless steel pipes are stainless steel pipes with various stainless steel hot rolled and cold rolled steel. It is widely used in petroleum, chemical equipment pipelines and stainless steel structural parts for various purposes. In addition to ensuring chemical composition and mechanical properties, these are used as steel pipes subjected to fluid pressure.
ASTM / ASME A / SA – 106 Grades B & C are utilized for services ranging from structural supports to steam drum headers with high temperature ranges up to 800 Fahrenheit while API 51, API 5L X Grades 42 thru 70 are utilized for the water and petroleum industry to transport liquids or as platforms on off shore rigs.