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Overview of stainless steel welded pipe industry

Views:6     Author:Site Editor     Publish Time: 2019-06-03      Origin:Site

Our country stainless steel welded pipe production after more than 50 years of development, stainless steel welded pipe production in our country has experienced more than 30 years of development. At present, China has built about 400 production lines (2008 data). By 2005, China has built nearly 10 stainless steel welded pipe factories with an annual capacity of more than 5,000 tons, including 4~5 factories specializing in the production of automobile exhaust pipe welded pipe (2008 data).


Since the 21st century, China's stainless steel welded pipe industry has had a greater development, China's stainless steel welded pipe manufacturing industry has taken initial shape. Domestic stainless steel welded pipe has been preliminarily used in corrosion resistant environment of petrochemical, nuclear power, shipbuilding, Marine engineering, paper making, automobile and other industries, and some products have been exported. However, most of these production lines can only produce civil decorative pipes and low-grade industrial pipes with a diameter of 114 (76) mm or less.


With the reform and development of China's stainless steel industry during the "13th five-year plan" period, the production of high quality plate and strip has increased, and the welding pipe blank conditions have been greatly improved. Therefore, we should rely on foreign advanced stainless steel welding technology construction process integrity, advanced equipment, post-treatment process equipment, increase the development of chemical, fertilizer, chemical fiber, petrochemical, energy and aerospace and other fields used in the high-grade, high value-added products and large specifications of products, to replace a part of seamless tube.


More than 30 years, China's stainless steel tube welding technology and equipment levels had certain enhancement, is mainly to adopt new technology and new equipment to improve production and expand the varieties, to adopt automatic control and nondestructive flaw detection to improve and guarantee the quality of our products and a few product quality has reached the international advanced level, but the international advanced level, compared to Chinese stainless steel HanGuanChang in technology and equipment level, product quality has a larger gap, need to undertake technical reformation and improve, to adapt to the demands of the development of national economy in our country.


Industry development direction


(1) the extension of stainless steel grade is the most important. There are only 17 types of steel in the current standard of stainless steel welded pipes in China (data of 2008), which is far less than the number of steel types specified in the corresponding standards of the United States, Europe and Japan. The welding pipes of dual-phase stainless steel, nitrogenous austenitic stainless steel, high-manganese austenitic stainless steel and super ferritic stainless steel need to be developed urgently. Some welded pipe factories have used imported raw materials to produce welded pipes that have not been included in the standard of welded pipes in China, such as 2205 duplex stainless steel welded pipes. However, the expansion of production and improvement of efficiency both depend on the localization of raw materials.


(2) improve the wall thickness range of stainless steel welded pipe. First of all, it should be noted that the us and European standards for stainless steel tubes, ASME b36.19m and ENY10220, stipulate that the wall thickness can be entered into the corresponding range of welded and seamless rolled steel tube wall thickness.


(3) improve the product grade of thin-wall stainless steel welded pipe and develop large-specification stainless steel welded pipe. 1~2mm stainless steel thin-wall welded pipe is now in mass production, but the added value of the product is not high, more prominent in the situation of raw material price rise. The only way to change this dilemma is to manufacture high value-added stainless steel welded pipes for boiler condensers, heat exchangers, superheaters and water heaters.


(4) accelerate the development of cryogenic processing of welded pipes, that is, HCW welded pipes. To do more than 35% wall reduction diameter cryogenic processing of welded pipe can not only completely improve the microstructure of stainless steel welding seam casting, improve the mechanical and corrosion resistance of stainless steel welded pipe, but also help to expand the size and specification of welded pipe diversification. Should become stainless steel welded pipe production another extension direction.


(5) GTAW, PAW is still the main method of stainless steel welding pipe. Laser welding is still in the experimental research stage, SAW et al is the preferred method for thick wall stainless steel pipe welding.


(6) high frequency resistance welding is a high productivity, low cost method, but only applicable to ferritic stainless steel and some austenitic stainless steel welding requirements are not high. This method is not suitable for stainless steel welded pipes in corrosive industrial environments.


(7) the production process of stainless steel welded pipe shall be strictly distinguished from whether filler metal is added, whether cold processing is carried out after welding and whether the final solid melt heat treatment is conducted. Stainless steel welded pipe with filler metal is not suitable for post-welding cold processing, and the welded pipe after cold processing should be subject to final welding heat treatment. For the welded stainless steel welded pipe supplied in the welding state, it should also distinguish whether the plates used have undergone welding heat treatment and give marks on the products.


(8) stainless steel welded pipe users should choose the type of welded pipe steel and agree on the welding method according to the corrosion medium type (acid or alkali, oxidation or reduction, impurity composition and concentration, etc.), temperature, possible corrosion form and other conditions, whether to cold press and final heat treatment and other manufacturing conditions.


(9) pay attention to heat treatment and finishing facilities. Whether stainless steel seamless or welded pipe production, according to the variety and quality requirements of production, equipped with modern heat treatment and finishing facilities is very important, to overcome the main production line neglect of heat treatment and finishing facilities phenomenon. It is necessary to adopt the non-oxidation continuous heat treatment furnace with protective gas to realize bright heat treatment. Adopt nondestructive testing equipment and strengthen monitoring means; Adopting high precision straightener, cold push press and spin type shrink mouth machine, multi-head polishing machine, full-length marking and other finishing devices, the stainless steel tube finishing and high efficiency, ensure the quality of stainless steel tube.


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