With the sustainable development of economy in our country, the country to vigorously develop the energy industry, long distance oil and gas pipeline is an important means of energy security, in the process of oil (gas) pipeline anticorrosion construction, steel tube surface treatment is one of the key factors determine the service life of the pipeline corrosion, it is a solid combination of anti-corrosion layer and steel tube can be provided. Verified by research institutions and the life of the coating depends on the quality of coating types, coating and environmental factors such as construction, steel tube surface treatment effects on coating life accounted for about 50%, therefore, should be in strict accordance with the specification on the coating on the surface of steel pipe requirements, continuously explore and summary, continuously improve steel pipe surface treatment.
High pressure boiler tube knowledge - high pressure boiler tube: 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, the boiler tube by the party under high temperature and high pressure pipe and works 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 20 g, 20 MNG, 25 MNG; 15 mog, alloy structural steel steel grade 20 crmog mog, 12, 15 crmog, 12 cr2mog, 12 crmovg, 12 cr3movsitib, etc; Heat resistant steel rust cr18ni9, 1 cr18ni11nb commonly used high pressure boiler tube, in addition to ensure that the chemical composition and mechanical properties to do hydrostatic test by the root, flaring, flattening test. Steel tube to heat treatment state delivery. In addition, the microstructure and grain size of finished steel pipe, the decarburization layer also has certain requirements. Geological drilling and oil drilling with seamless steel tube; Proven underground strata structure and groundwater, oil, gas and mineral resources, make use of the rig drilling Wells. Mining more from drilling, oil and gas geological drilling in oil drilling in seamless steel pipe is the main drilling equipment, mainly including core tube, core tube, casing, drill pipe, etc. 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 common steel grade dz45 MNB 45, 50 mn; Dz50 40 mn2, 40 mn2si; Dz55 40 mn2mo, 40 MNVB; 40 mnmob dz60, dz65 27 mnmovb. Steel pipe is a heat treatment state delivery. Petroleum cracking tube: used in oil refinery furnace tube, seamless tube heat exchanger tube and pipe. Commonly used high quality carbon steel (10, 20), alloy steel (12 crmo, 15 crmo), heat resistant steel (12 cr2mo, 15 cr5mo), stainless steel cr18ni9 (1, 1 cr18ni9ti) manufacturing. Steel pipe except to the chemical composition and various mechanical properties, and ensure that the water pressure, flattening, flaring test, and the surface quality and nondestructive inspection. Steel pipe in heat treatment state delivery. Stainless steel pipe: with all kinds of stainless steel hot rolling and cold rolling stainless steel tube, pipe is widely used in petroleum, chemical industry equipment and various USES of the stainless steel structural parts, in addition to ensure that the chemical composition and mechanical properties, all steel pipe is used as the fluid under pressure to keep the water pressure test. All kinds of special steel pipe to guarantee conditions by the regulation.
Straight seam steel pipe and spiral steel pipe is a kind of welded steel pipe, they are widely used in the construction of national product, straight seam steel pipe and spiral steel pipe due to the different production process has many differences, therefore, the following specific issues about the difference between straight seam steel pipe and spiral steel pipe. Straight seam welded pipe production technology is relatively simple, the main production process with high frequency straight seam welded steel tubes and submerged arc welding and straight seam steel pipe, straight seam pipe production with high efficiency, low cost, rapid development. The strength of the spiral welded pipe is generally higher than straight seam welded pipe, the main production process is submerged arc welding, spiral steel pipe can use the same width of different diameter welded pipe billet production, can also use a narrower billet production of larger diameter welded pipe. But compared with the same length of straight seam pipe, weld length by 30 ~ 100%, and the production speed is low. As a result, a small diameter welded pipe are mostly with straight seam welding, large diameter welded pipe for the most part adopts spiral welded. They have been used in the industry production of straight steel tube located at a t-shaped welding technology, the short sections of straight seam steel pipe for docking, the length of the connect accords with the need of engineering, t the probability straight seam welded steel defect is greatly improved, and the t-shaped seam welding residual stress is larger, the stress state of the weld metal are often in a three to increase the possibility of a crack.
At present, China's domestic market share of oil well pipe has been more than 80%, and 2 years in a row as net export products. In regard to the development of varieties, many domestic enterprises innovation, not only produced according to the requirement of API standard K, N, C and P steel casing, also according to user requirements developed with independent intellectual property rights of the series of casing, such as tianjin steel tube company developed a TP series the collapse resistance of casing, casing corrosion resistance, resistance to high temperature thermal recovery Wells with casing, ultra deep well with button and special gas tightness casing pipe, including TPl30TT high collapse casing its collapsing strength reached more than 167 mpa. TPll0TSS high collapse casing corrosion resistance in 5% sodium chloride, acetic acid, 5% of oxidation corrosion in the solution, 720 hours not broken; TP140V casing under the well depth of 6936 meters (the recent record will be broken). A NC 3 cr co2 corrosion resistance casing has batch sent to tarim oilfield well use. Baosteel, chengdu seamless also have developed their own products. Although Chinese seamless steel tube industry in the oil well pipe has made remarkable achievements, but in some high-end product development there is no pass, such as 13 cr, super 13 cr steel inclusion and control the content of S and P (S less than 10 PPM, P is less than 15 parts per million (PPM), the performance of the heat treatment control, and thread processing of quality control still exist a series of problems, such as flexible tubing, the development of the expansion casing is still blank.
With the development of the pipeline steel plate technology and the progress of welded pipe forming, welding technology, the application range of the pipe with welded pipe in gradually expanding, especially in the large diameter welded pipe class scope advantages more apparent, and cost factor, welded pipe has been dominant in the field of line pipe, which limits the development of the seamless line pipe. In 2007 domestic seamless line pipe, mainly including X42-70 in steel grade, varieties have a land line pipe and seabed pipeline. Production of high grade pipeline pipe currently USES micro alloying heat treatment process, the cost of production of seamless tube was obviously higher than that of welded pipe, and with the improvement of steel grade, such as the above X80 grade pipeline steel tube limits on carbon equivalent, seamless steel tube of conventional technology is difficult to meet user requirements; Currently all seamless steel tube plant in order to improve the line pipe corrosion resistance, the use of stable performance and low temperature, high temperature environment to carry out the scientific research work.