Seamless steel pipe: seamless steel tube is made of ingot or solid tube blank by perforation, then by hot rolling, cold rolling or cold drawing. The specification of seamless steel tube is expressed by outer diameter * wall thickness mm. Seamless steel tubes are divided into hot rolling and cold rolling (pull) seamless steel tubes.
Hot-rolled seamless steel pipe is divided into general steel pipe, low and medium pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, petroleum cracking pipe, geological steel pipe and other steel pipes.
Cold-rolled (dial) seamless steel tube in addition to the general steel tube, low medium pressure boiler pipe, high pressure boiler tube, alloy steel pipe, steel pipe, stainless steel tube, petroleum cracking, other steel pipe outside, also include carbon thin wall steel tube, alloy thin wall steel pipes, thin-walled stainless steel pipe, steel pipe.
The outer diameter of hot-rolled seamless tube is generally greater than 32mm, and the wall thickness is 2.5-75mm. The outer diameter of cold-rolled seamless steel tube can reach 6mm, the wall thickness can reach 0.25mm, the outer diameter of thin-walled tube can reach 5mm, the wall thickness is less than 0.25mm, and the precision of cold-rolled steel tube is higher than that of hot-rolled steel tube.
Generally, seamless steel pipe is made of (10, 20, 35, 45) and other high quality carbon bonded steel such as 16Mn, 5MnV or (40Cr, 30CrMnSi, 45Mn2, 40MnB). (10, 20) and other low-carbon steel seamless pipe is mainly used for fluid transportation pipeline. (45, 40Cr) seamless pipe made of medium carbon steel is used to make mechanical parts, such as mechanical parts of automobiles and tractors.
In general, seamless steel tube to ensure the strength and flat test. Hot rolled steel pipe delivered in hot rolled or heat treated state; Cold rolling is delivered in heat treatment condition.
Low medium pressure boiler seamless steel pipe: used in the manufacture of all kinds of low intermediate pressure boiler superheated steam pipe, water pipe, water wall tube and locomotive boiler superheated steam pipe, pipes, small pipe and tube arch brick, etc. Low medium pressure boiler with high quality carbon structural steel hot rolled or cold rolled (dial) seamless steel tube, mainly use (10, 20) steel manufacturing, in addition to guarantee the chemical composition and mechanical properties to do water pressure test, edge, flaring, flattening test, etc. Hot rolling shall be delivered in hot rolling and cold rolling shall be delivered in heat treatment.
High-pressure boiler tubes: mainly used in the manufacture of high pressure and over pressure steam boiler pipes, etc. With high quality carbon structural steel, alloy steel and stainless heat resistant steel seamless steel tube, these often under high temperature and high pressure boiler tube, tube in high temperature flue gas and steam will happen under the action of oxidation and corrosion, so the steel pipe with high rupture strength, high oxidation resistance, and have good organizational stability, using steel grade are: high quality carbon structural steel grade have (20 g, 20 MNG, 25 MNG); Alloy structural steel Numbers (15MoG, 20MoG, 12CrMoG, 15CrMoG, 12Cr2MoG, 12CrMoVG, 12Cr3MoVSiTiB); Rust-resistant steel is commonly used (1Cr18Ni9, 1Cr18Ni11Nb). In addition to ensuring chemical composition and mechanical properties, water pressure test should be carried out for high pressure boiler tubes one by one, and expansion and flattening test should be conducted. Steel pipes are delivered in heat treatment condition. In addition, there are some requirements for the microstructure, grain size and decarbonization of finished steel pipes.
Seamless steel pipes for geological drilling and oil drilling: drilling RIGS to explore underground rock formations, groundwater, petroleum, natural gas and mineral resources. Drilling is more indispensable for oil and natural gas exploitation. Seamless steel pipe used for drilling in geological drilling is the main equipment for drilling, mainly including outer core pipe, inner core pipe, casing pipe and drill pipe. Due to the drilling pipe to go deep into the thousands of meters formation depth work, working conditions is very complex, drill pipe under pull, pressure, bending, torsion and uneven impact load stress, but also by mud, rocks and wear, therefore, requires tubing must have sufficient strength, hardness, wear resistance and impact toughness, steel pipe steel with “DZ” pinyin “(geology) plus number one on behalf of the steel yield point, said commonly used steel grade have DZ45 (45 MNB, 50 mn); DZ50’s (40Mn2, 40Mn2Si); DZ55’s (40Mn2Mo, 40MnVB); DZ60’s (40MnMoB); DZ65’s (27MnMoVB). Steel pipes are delivered in heat treatment.
Oil cracking pipe: seamless tube for furnace tube, heat exchanger tube and pipeline in petroleum refinery. High quality carbon steel (10, 20), alloy steel (12CrMo, 15CrMo), heat resistant steel (12Cr2Mo, 15Cr5Mo), stainless steel (1Cr18Ni9, 1Cr18Ni9Ti) are commonly used. In addition to the chemical composition and various mechanical properties, the steel pipe must be tested for water pressure, flattening and expanding, as well as surface quality and non-destructive testing. Steel pipes are delivered under heat treatment.