How to identify high quality GB/T9948 seamless carbon steel pipe

Classification of 3087 seamless carbon steel pipes: seamless steel pipes are divided into hot-rolled seamless steel pipes and cold-rolled seamless steel pipes.

Hot-rolled seamless steel pipes are divided into ordinary steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, geological steel pipes and other steel pipes.

Cold-rolled seamless steel pipes are divided into ordinary steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, oil cracking pipes, other steel pipes, carbon thin-walled steel pipes and alloy thin-walled steel pipes. Stainless steel thin-walled steel pipe and special-shaped steel pipe. The outer diameter of the hot-rolled seamless steel pipe is generally greater than 32mm, the wall thickness is 2.5-75mm, the outer diameter of the cold-rolled seamless steel pipe can be 6mm, the wall thickness can be 0.25mm, the outer diameter of the thin-walled pipe can reach 5mm, and the wall thickness can be 5mm. less than 0.25mm. Cold rolling has higher dimensional accuracy than hot rolling.
Generally, seamless steel pipes are used: 10, 20, 30, 35, 45 and other high-quality carbon steels such as 16Mn, 5MnV and other low-alloy structural steels or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other alloy steels are hot-rolled and rolled or cold-rolled. Seamless pipes made of low carbon steel such as 10 and 20 are mainly used for fluid transportation pipelines. 45, 40Cr and other medium carbon steel seamless pipes are used to manufacture mechanical parts, such as the stressed parts of automobiles and tractors. Generally, seamless steel pipes need to ensure strength and flattening tests. Hot-rolled steel pipes are delivered in hot-rolled or heat-treated state; cold-rolled steel pipes are delivered in heat-treated state.
Seamless steel pipes for low and medium pressure boilers: used to manufacture various low and medium pressure boilers, superheated steam pipes, boiling water pipes, water wall pipes and locomotive boiler superheated steam pipes, large smoke pipes, small smoke pipes and arch brick pipes. Hot-rolled or cold-rolled seamless steel pipes are made of high-quality carbon structural steel. Mainly made of No. 10 and No. 20 steel, in addition to ensuring chemical composition and mechanical properties, hydrostatic testing, hemming, flaring and flattening are also required. Hot-rolled is delivered in hot-rolled state, and cold-rolled is delivered in heat-treated state.
High-pressure boiler steel pipe: It is mainly used to manufacture high-quality carbon structural steel, alloy structural steel and stainless heat-resistant steel seamless steel pipe for steam boiler pipes with high pressure and above. These boiler tubes often operate at high temperatures and pressures. The pipeline will also be oxidized and corroded under the action of high temperature flue gas and water vapor. Therefore, steel pipes are required to have high durability, high oxidation resistance and good structural stability. The steel grade is: high quality carbon structure. Steels include 20G, 20MnG, 25MnG; alloy structural steels No.15MoG, 20MoG, 12CrMoG, 15CrMoG, 12Cr2MoG, 12CrMoVG, 12Cr3MoVSiTiB, etc.; rust-proof and heat-resistant steels commonly used 1Cr18Ni9, 1Cr18Ni11Nb high-pressure boiler tubes, in order to ensure chemical composition and mechanical properties, It is necessary to do the hydraulic test one by one, and do the flaring and flattening test. Steel pipes are delivered in heat-treated condition. In addition, there are certain requirements for the microstructure, grain size and decarburization layer of the finished steel pipe.
Seamless steel pipes for geological drilling and oil drilling: for drilling underground structures, groundwater, oil, gas and mineral resources. Oil and gas extraction is inseparable from drilling. Seamless steel pipe for oil drilling is the main equipment for drilling, mainly including core outer pipe, core inner pipe, casing and drill pipe. Because the depth of the drill pipe is enough to work at a depth of several kilometers, the working conditions are extremely complex, and the drill pipe has to bear the stresses such as tension, compression, bending, torsion and unbalanced impact loads, and also bears mud and stone wear. Therefore, pipes are required. It must have sufficient strength, hardness, wear resistance and impact toughness. The steel used for steel pipes is represented by "DZ" (geological Chinese Pinyin prefix) plus numbers to indicate the yield point of the steel. The commonly used steel grades are DZ45 45MnB, 50Mn; DZ50 40Mn2, 40Mn2Si ; 40Mn2Mo, 40MnVB of DZ55; 40MnMoB of DZ60, 27MnMoVB of DZ65. Steel pipes are delivered in heat-treated condition.
Petroleum Cracking Tubes: Seamless tubes for furnace tubes, heat exchanger tubes and pipes used in refineries. Commonly used high-quality carbon steel (10, 20), alloy steel (12CrMo, 15CrMo), heat-resistant steel (12Cr2Mo, 15Cr5Mo), stainless steel (1Cr18Ni9, 1Cr18Ni9Ti). In addition to the chemical composition and various mechanical properties, the steel pipe must also ensure water pressure, flattening, flaring and other tests, as well as surface quality and non-destructive testing. Steel pipes are delivered in heat-treated condition. Stainless steel pipe: Stainless steel pipe has various hot-rolled and cold-rolled stainless steel, which is widely used in petroleum and chemical equipment pipelines and stainless steel structural parts for various purposes. In addition to chemical composition and mechanical properties, it is used as a steel pipe to withstand fluid pressure. Make sure that the hydrostatic test is qualified. All kinds of special steel pipes must be guaranteed according to regulations.

Read more ： seamless black steel pipe 

Article source: https://article-realm.com/article/Finance/29724-How-to-identify-high-quality-GB-T9948-seamless-carbon-steel-pipe.html