Application and analysis of stainless steel welded pipes in different industries

Date:2023-06-19View:268Tags:stainless steel welded pipes,stainless steel plate,stainless steel coil
Stainless steel welded pipe is an important field of stainless steel plate/coil deep processing, and it is also the main material for laying corrosion-resistant pipes in petroleum, chemical industry, medicine, food, and laying corrosion-resistant pipes. It is the main component of power generation equipment, shipbuilding industry, refrigeration equipment, and seawater desalination equipment. Therefore, stainless steel welded pipes have attracted more and more attention from users and attention from relevant departments.
stainless steel welded pipesApplication of stainless steel welded pipes
The main characteristics of stainless steel welded pipe production are: light production equipment, less investment, fast construction speed, simple welding method, wide range of product specifications, high dimensional accuracy, small wall thickness deviation, smooth surface, and high yield. In the case of high-volume production, welded pipes cost more than 20% less than seamless pipes. In recent years, China has adopted the "welding-cold rolling" and "welding-cold drawing" process to produce stainless steel pipes. After slitting and forming cold-rolled coils according to specifications, they are welded into pipes by multi-gun argon arc welding machines, and then cold-rolled coils are used to form pipes. Rolling (pulling), so that the performance indicators of the weld can be basically consistent with the base metal, and the product quality is obviously improved. From this point of view, the advantages of replacing stainless steel seamless pipes with stainless steel welded pipes are becoming more and more obvious.

2. The overall situation of the stainless steel welded pipe industry

With the rapid development of global economic construction, the consumption of stainless steel continues to increase, and the demand for stainless steel pipes is also expanding day by day, and the market prospect is promising. The market demand for stainless steel seamless pipes is manifested in basic industries, such as petroleum, chemical industry, power generation, etc., whose demand accounts for two-thirds of the total consumption of stainless steel seamless pipes, as well as automobile, shipbuilding, construction and environmental protection industries. Greater demand. Stainless steel welded pipes are currently mainly used in urban landscape and architectural decoration industries. From the perspective of domestic stainless steel pipe products, the steel grades have developed from a single austenitic steel to martensitic and ferritic steel, dual-phase steel, and high-alloy steel; product varieties include: seamless steel pipes, including cold-drawn pipes, cold-rolled pipes Tubes, hot extrusion tubes, centrifugal casting tubes, spinning tubes; welded tubes include: plasma welding, argon arc welding, submerged arc welding, light speed welding and high frequency welding and other welded tubes. The stainless steel tubes that can be produced basically cover the world There are more than 100 kinds of specifications and varieties of stainless steel special-shaped pipes according to the standards of various countries, and the products are used in many fields of industry and civil use. But in general, there is a certain gap between domestic stainless steel pipes and market demand in terms of variety, specification, quantity and quality:

In terms of the product and quantity of stainless steel pipes: the output of ordinary stainless steel pipes for general purposes has been balanced with the overall market demand. The production capacity of seamless pipes is greater than the market demand, resulting in excess production; the market supply of medium and low-grade standard stainless steel decorative welded pipes exceeds demand; the production capacity of higher-standard industrial welded pipes is insufficient, especially for high-demand industrial pipes, such as power stations. High-pressure stainless steel boiler tubes are basically blank.

In terms of the specifications of stainless steel pipe products: the production capacity of small and medium-diameter stainless steel pipes for general purposes will meet the market demand; the market demand for large-diameter and high-demand stainless steel pipes is in short supply, and the gap is relatively large. Imports made up the shortfall. Another example is super-long (greater than 15m) ultra-long pipes, which are rarely produced in China and basically rely on imports.

In terms of varieties of stainless steel pipes: 304L, 316L and other ultra-low carbon stainless steels are widely used abroad. The quality of domestic urea grade and high-precision stainless steel is still difficult to guarantee; some special stainless steel tubes with high technical difficulty and high quality requirements, such as heat exchanger tubes for power plant boilers, urea tubes for fertilizer plants, oil well tubes, etc. Mainly rely on imports; some duplex stainless steel pipes with good corrosion resistance are rarely produced in China, which cannot meet market demand.

From the perspective of the production of stainless steel pipes: In the past ten years, with the rapid expansion of application fields and the attraction of high added value of stainless steel pipes, the number of enterprises producing stainless steel pipes has grown from a dozen in the 1980s to more than 400 at present. , the comprehensive production and processing capacity exceeds 1 million tons, and there are nearly 300 stainless steel seamless steel pipe production enterprises, with a production capacity of 500,000 or more in 2007, and nearly 600 stainless steel welded pipe production lines, with an annual production capacity of more than 800,000 tons, which is greater than the demand. There are very few enterprises with an output of 5,000 tons, and most of them are small factories with an annual output of less than 2,000 tons. The production capacity of my country's industrial stainless steel welded pipes does not match the domestic market demand. Most of the existing stainless steel welded pipe units are not equipped with complete equipment, such as the lack of heat treatment and online testing equipment, so that the production capacity of the unit cannot be fully utilized. Generally, only It can produce general decorative tubes, but only a few manufacturers can produce high-demand chemical machinery tubes and heat exchanger tubes.

3. Super ferritic stainless steel welded pipe

Under the condition of brackish water and polluted seawater as the cooling medium, the corrosion resistance of copper and copper alloy pipes as condenser pipes can no longer meet the requirements for use. With the advancement and development of metallurgical technology, high-performance stainless steel welded pipes and titanium welded pipes are effective ways to replace copper alloy condenser tubes. At present, the selection of condenser tubes for domestic power stations is carried out in accordance with the requirements of DL/T712-2000 "Guidelines for Selection of Condenser Tubes in Thermal Power Plants". Under the condition of seawater as the cooling medium, HAl77-2 and BFe can be used 30-1-1, TA1 welded pipe. In the world, various brands of high-performance stainless steel tubes have been widely used in the condenser heat exchange tubes of coastal power stations. In addition to titanium, there are also high-performance austenitic stainless steel (such as AL-6XN, 254SMO) and high-performance ferritic stainless steel (such as AL29-4C, SEA-CURE). These materials are able to operate in seawater from the perspective of corrosion resistance.

In the United States, high-performance austenitic stainless steel welded pipes were first used in power station condensers in 1973, and high-performance austenitic stainless steel welded pipes were basically used before 1979. High-performance ferritic stainless steel welded pipes have been used in power station condensers since 1979. Although the share in the next few years is not large, the growth rate is relatively fast. After 2000, high-performance austenitic stainless steel welded pipes are basically no longer used, and high-performance ferritic stainless steel welded pipes are used. Since 2003, in terms of actual cumulative total use, high-performance ferritic stainless steel welded pipes have also exceeded high-performance austenitic stainless steel welded pipes. Tensitic stainless steel welded pipe.

The performance comparison between ferritic stainless steel and austenitic stainless steel is as follows:

Elastic modulus: High-performance ferritic stainless steel is slightly larger than high-performance austenitic stainless steel, so the shock resistance of high-performance ferritic stainless steel is slightly stronger than that of high-performance austenitic stainless steel, and thinner pipe walls can be used instead of Vibration is generated, and thin walls are also more conducive to heat transfer.

Thermal conductivity: High-performance ferritic stainless steel is larger than high-performance austenitic stainless steel, so the heat transfer performance of high-performance ferritic stainless steel is better than that of high-performance austenitic stainless steel.

Linear expansion coefficient: High-performance ferritic stainless steel is closer to the linear expansion coefficient of carbon steel than high-performance austenitic stainless steel, so the internal stress of high-performance ferritic stainless steel due to thermal expansion is small, and the surface oxide film is due to the difference in thermal expansion coefficient. And the tendency of spalling or cracking is small, and it is more suitable for the environment of high temperature cycle oxidation.


Density: High-performance ferritic stainless steel is smaller than high-performance austenitic stainless steel. Under the same volume condition, high-performance ferritic stainless steel is lighter than high-performance austenitic stainless steel.


These two types of high-performance stainless steel welded pipes have excellent corrosion resistance to various types of corrosion, such as chlorine pitting, steam erosion, stress corrosion, and marine corrosion. Therefore, both types of high-performance stainless steel welded pipes can be used in condensers of coastal power stations (including polluted seawater).

The specific corrosion resistance tests show that compared with high-performance austenitic stainless steel (AL-6XN), high-performance ferritic stainless steel (SEA-CUER.) has better resistance to chloride corrosion and sediment erosion. performance.

Super ferritic stainless steel has excellent comprehensive performance, and has been widely used in the United States and other countries, and has a good prospect in China.

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