Stainless steel welded pipe is also called the welded stainless steel pipe, usually with unit and mould will be stainless steel sheet or strip coiling molding made of stainless steel welded pipe again, after the production process of this product is simple, so the production efficiency is also good, more varieties of specifications, traditionally the use strength than seamless steel tube. But along with the progress of the technological level and production equipment, the welded pipe weld quality enhances unceasingly, has in many areas, especially in heat exchange equipment with pipe, decorative and low pressure fluid in the tube to replace the stainless steel seamless tube.
Now the main production process of the mainstream stainless steel pipe is argon arc welding, high frequency welding, composite welding and so on.The advantages and disadvantages of these stainless steel processing techniques are described in detail below.
Welding technology of stainless steel – argon arc welding
Due to the penetration depth of molten stainless steel welded pipe requirements, do not contain oxide inclusions, heat affected zone as small as possible, and argon arc welding technology of tungsten inert gas protection good applicability, high welding quality and penetration performance is good, the process of stainless steel welded pipe is multi-purpose in chemical industry, nuclear industry and food industries.
However, the shortage of argon arc welding is not high.In order to improve the welding speed, the welding method of multi-electrode multiple welding torch was developed by single electrode welding torch.In the 1970s Germany first adopted the multi-welding torch line in a straight line in the direction of the weld line, forming a long heat flow distribution, which obviously improved the welding speed.It is generally used for argon arc welding of three electrode welding torch, welding steel tube wall thickness S > 2mm, welding speed is 3-4 times higher than single welding torch, and welding quality can be improved.Argon arc welding and plasma welding can weld a larger steel tube, in addition, 5-10% of the hydrogen in argon, then high frequency pulse welding power, can also improve the welding speed.Argon arc welding is suitable for welding of austenitic and iron – rope stainless steel pipes.
Stainless steel welding technology – high frequency welding
High frequency welding is used in the production of carbon steel welded pipe for nearly half a century, but it is a new technology in welding stainless steel tube.Because of its better economy, it is often used in architectural decoration, household appliances and mechanical structure.
High frequency welding efficiency is very good. Different materials and stainless steel tubes with thick outer walls have high welding speed.The maximum welding speed is more than 10 times of argon arc welding.Therefore, it is cost-effective to produce ordinary stainless steel welded pipes.
However, because of high frequency welding speed, it is difficult to remove burr.Therefore, the high frequency welding stainless steel tube cannot be used in the industries of chemical industry and nuclear industry.
In addition, high frequency welding can weld various types of austenitic stainless steel tubes.And the existing new technology can be successfully welded iron – solid stainless steel AISI409 and other steel types.
Welding technology of stainless steel – combined welding technology
Because of various welding methods have advantages and disadvantages, so in order to foster strengths and circumvent weaknesses, the many kinds of welding methods are combined to form a new welding technology, can achieve the requirement of stainless steel welded pipe quality and production efficiency, and this is now and the future of stainless steel welded pipe technology and its development direction.
The combined welding method is: argon arc welding, plasma welding, high frequency welding and plasma welding, high frequency preheating + 3 welding torch argon arc welding, high frequency preheating + plasma + argon arc welding.Combined welding speed is very obvious.To adopt the combination of high frequency preheating welded steel pipe weld quality and conventional argon arc welding, plasma welding, the welding operation is simple, easy to implement the whole welding system automation, this combination is easy to interface with the existing high frequency welding equipment, low investment cost, profit is very good.
Stainless steel tubes are also increasingly used in people’s lives as demand for stainless steel continues to grow.Even in other traditional applications of the materials, stainless steel pipe is being replaced, especially stainless steel welded pipe used in industry demand is higher, automobile, shipbuilding, construction, environmental protection, the pressure piping, mechanical components, etc., have in-depth every aspect.
Source: China Stainless Welded Pipe Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)