Now the production technology of stainless steel welded pipe is relatively perfect. It has replaced seamless steel pipes in many aspects, such as petroleum, automobile, paper making, air conditioning and so on, and its price is less than 1/5 of seamless pipe. The market demand of stainless steel seamless pipe is mainly manifested in basic industries, including oil, chemical, power generation and so on, which account for 1/3 of the total consumption of stainless steel seamless pipes.
But more producers choose stainless steel welded steel pipe in addition to its cheaper price, but also mainly its own characteristics and advantages. First, look at the manufacturing process of small caliber stainless steel welded pipe, the sequence is stainless steel plate, strip, forming, melting, bright solution treatment, internal and external weld treatment, eddy current testing, laser diameter measurement, straightening and storage.
Through the production process, it can be seen that the stainless steel welded pipe is continuous online production. The thicker the wall thickness is, the higher the investment of the unit and the melting equipment will be. The lower the economy and practicability of the stainless steel welded pipe is. The wall thickness of the thinner, the input-output ratio will decrease, and the product process also affects its advantages and disadvantages, usually welded pipe with higher precision and more uniform wall thickness, stainless steel pipe fittings inner surface of high brightness (steel plate surface surface brightness level decision), can be arbitrarily set foot. So it shows its economy and beauty in the use of high – precision, medium and low – pressure fluid.
Let’s take a look at the manufacturing process of seamless steel pipe. The sequence is smelting, ingot, rolling, sawing, peeling, perforating, annealing, pickling, up ash, cold drawing, cutting, pickling and final storage. In addition to that of thick wall and high strength mechanical timber structure advantages, low common seamless steel pipe precision, uneven thickness, the appearance of low brightness pipe length high cost, and the appearance of pitting and black spots is not easy to remove.
The following is the contrast between the two more clearly, first look at the coverage, stainless steel seamless pipe can do small diameter thick wall and large diameter thick wall, but generally they are affected by the length limit; but the stainless steel pipe wall thickness is thinner can do, can do with large diameter and small wall thickness and small diameter and small wall thick, theoretically, stainless steel coil pipe with long, how long can do. In other words, the thicker the more suitable for the use of seamless pipe, the thinner the more suitable for the use of welded pipe.
The second is the average and concentricity of the pipe wall thickness. In this respect, the stainless steel welded pipe is better than the stainless steel seamless pipe. Because the plate thickness tolerance of the cold rolled plate is more average, the deformation is average during the molding process. The seamless pipe rolling process is influenced by the equipment precision and other factors, and there is a problem of uneven thickness and concentricity, but the roundness is better than that of the welded pipe.
The other is the performance, the average quality of stainless steel welded pipe, appearance quality, expansion pipe performance, bending, pier head performance are better. Because the average performance of the cold rolled plate is better than that of the pipe, and the welded pipe is generally on line solution, and the heat treatment is more average, and the performance is more stable. The stainless steel seamless pipe is sampled at different positions on the same pipe, and the performance will be different.
In addition, the price is the price, the price of stainless steel welded pipe is cheaper.
In the end, the bearing capacity of the stainless steel seamless pipe is slightly higher than that of the welded pipe under the same specification. But the stainless steel welded pipe is formed because of the stainless steel sheet which is used, the processing is relatively simple, so the delivery time is shorter. Stainless steel seamless pipe should start from round steel, perforated and then draw cold drawn and cold rolled many times, and then produce products after solid solution annealing and acid washing. The production cycle is longer.
To sum up, the application of stainless steel welded pipe is more obvious than that of stainless steel seamless pipe, of course it is under the premise of selecting high quality and qualified stainless steel welded pipe.
Source: China Stainless Steel Pipe Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)