Stainless welded tube used for heat exchanger

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Seamless and Welded Stainless Tube for Heat Exchanger

Developement of stainless welded tube

In recent years, the development trend of stainless steel welded pipes has been relatively good. Regardless of the scale, quality, and production technology, there have been relatively large advances, and in particular its demand areas have also gradually expanded. In addition, as the stainless steel welded pipe process becomes more and more mature, it can gradually replace the stainless steel seamless pipe in many applications, such as: heat exchanger equipment, medium and low pressure boiler tubes and so on.

Stainless Steel Welded Pipe Production Features:

light production equipment, low investment, construction speed, welding method is simple, a wide range of product specifications, high dimensional accuracy, small wall thickness deviation, smooth surface, high rate of finished products. In the case of mass production, the cost of the welded pipe is 20% lower than that of the seamless pipe. In recent years, the “welding-cold rolling” process of producing stainless steel tubes used in the country has been cold-rolled (pulled out) after cold-rolled coils have been slit and shaped according to specifications, and then welded into tubes by multiple gun argon arc welders. The performance indicators of the weld can be basically the same as the parent metal, and the product quality is obviously improved. Therefore, the advantages of using stainless steel welded tubes instead of stainless steel seamless tubes have become increasingly apparent.

Stainless Steel Welded Pipe Production Advantages:

Stainless Heat Exchanger

First, in the production process of stainless steel welded pipe, the pipe body will be uniformly extruded, and then after online bright solid annealing, the surface becomes very smooth, and the smooth surface is not easy to scale, with anti-fouling Features. This is both beneficial to heat dissipation and does not require frequent cleaning, saving time and effort. Secondly, the welded pipe is a deep-processed product of the plate. Its advantage of uniform wall thickness is unparalleled, and it can also be arbitrarily fixed in length with high accuracy. Again, the stainless steel material is resistant to corrosion and has a long life in use.

Status of Stainless Steel Welded Pipe Products:

The production capacity of stainless steel welded pipes for industrial use in China is not compatible with the domestic market demand. Most of the existing stainless steel welded pipe sets are not equipped with the necessary equipment, such as the lack of heat treatment and on-line testing equipment, which will not allow the production capacity of the units to be obtained. To give full play, generally only general decorative tubes can be produced, but the supply of medium-to-low-grade stainless steel decorative welded tubes exceeds demand; higher-standard industrial welded tubes, such as chemical machinery tubes and heat exchanger tubes, have only a few manufacturers. Can produce, a serious shortage of production capacity.

Welded Stainles Steel Tube

Stainless Steel Tube Chemical Composition:

Chemical composition           Element 201 202 304 316 S31803 S32750  
C ≤0.15 ≤0.15 ≤0.08 ≤0.08 ≤0.030 ≤0.030  
Si ≤1.00 ≤1.00 ≤1.00 ≤1.00 ≤1.00 ≤0.80  
Mn 5.5-7.5 7.5-10.0 ≤2.00 ≤2.00 ≤2.00 ≤1.20  
P ≤0.060 ≤0.060 ≤0.045 ≤0.045 ≤0.030 ≤0.035  
S ≤0.030 ≤0.030 ≤0.030 ≤0.030 ≤0.020 ≤0.020  
Cr 16-18 17-19 18-20 16-18 21-23 21-23  
Ni 3.5-5.5 4.0-6.0 42958 43022 4.5-6.5 6.0-8.0  
Mo       2.0-3.0 2.5-3.5 3.0-5.0  
N ≤0.25 ≤0.25     0.08-0.2 0.24-0.32  
Cu           ≤0.50  
Mechanical properties     Material Item 201 202 304 316 S31803 S32750
Tensile Strength (MPa) ≥655 ≥620 ≥515 ≥515 ≥620 ≥800
Yield Strength (MPa) ≥260 ≥310 ≥205 ≥205 ≥450 ≥550
Elongation (%) ≥35 ≥35 ≥35 ≥35 ≥25 ≥15
Hardness (HV) ≤230 ≤230 ≤200 ≤200 ≤303 ≤323

Stainless Steel Tube Product Dimension:

Name Stainless Steel tube
Standard ASTM A213,ASTM A312,ASTM A789,ASTM A790
Material Grade 201/202/304/316/S31803/S32750
Outer Diameter 0.1mm--219.1mm
Thickness 0.05mm - 20mm
Length ≤12000mm or as per customer request
Tolerance   a) Outer Diameter:  +/- 0.2mm
b) Thickness: +/- 10% OR   as customer request 
c) Length: +/- 10mm
Surface   Satin / Hairline :180#, 320#
Polish   : 400# ,600# ,800# or  Mirror surface
Application Decoration ,( Processed into  railings, handrails, doors and Windows ),medical,industry,etc
Packaing  Plastic bag/woven packing(please send details packing to us if you have other requirements)

Can Welded Pipe Work on Heat Exchange Equipment?

304 Welded Stainless Steel Tube

Higher standard product tube is possible, the heat exchanger tube is an indispensable part of the tubular heat exchanger equipment. Generally, the heat exchanger tube is selected according to the pressure and the fluid medium. One of the mistakes in the selection of heat exchanger tubes on the market today is that stainless steel welded tubes cannot be used as heat exchanger tubes, but GB/151-1999 clearly specifies that stainless steel welded tubes can be selected when the tube pressure is ≤ 6.4 MPa. In particular, now that the stainless steel welded pipe production process is very mature, it can fully meet the needs of the general heat exchanger tubes and shows its unique advantages.

Mature production process, austenitic stainless steel welded pipe will be the first choice

Because the heat exchanger tube constitutes the heat transfer surface of the heat exchanger, the size of the heat exchanger tube has a great influence on the heat transfer. When a small diameter pipe is used, the heat exchange unit has a large heat exchange area per unit volume, the equipment is relatively compact, the metal consumption of the unit heat transfer area is small, and the heat transfer coefficient is also high. Although manufacturing troubles, the use of austenitic stainless steel welded pipe as a heat exchanger tube can avoid the above problems, because the austenitic stainless steel pipe has both good corrosion resistance and a smooth surface, while the production process is mature, so the austenitic Stainless steel welded pipe is the first choice for heat exchanger tubes.

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