How to Maintain the Quality of the Stainless Steel Pipe

The time of issue:2014-5-22 10:10:56       Author:

Firstly, in order to enhance the properties of the weld and satisfy the demands of the application, we should select filler metal for stainless steel pipe. The maximum carbon content which is supplied by the filler metals designed with an “L” is lower compared to the welded steel pipe. Therefore, this kind of stainless steel pipe is more useful for corrosion resistance in low carbon stainless alloys. To maintain corrosion resistance, controlling the carbon content low is vital in high purity applications, for example, food, and beverage and pharmaceutical. On the contrary, the filler metal which is designed with “H” supplies higher carbon content for applications that need higher temperatures. The puddle fluidity can be increased by the stainless steel pipe with filler metals of higher silicon levels, and then contributes to the increasing of the travel speeds and the greater productivity.

One of the causes to control the corrosion resistance of the stainless steel pipe is sensitization which can be influenced by the filler metal and the weld cooling-temperature. The stainless steel pipe has a stainless layer because of the chromium oxide. When the carbon levels in the weld and the other zone that affected by heat are raised, the chromium carbides may form, and then in turn can prevent the formation of chromium oxide. Therefore, it is useful for corrosion resistance.

The methods to combat sensitization of the stainless steel pipe are as follows. Firstly, reducing the carbon level in the welding application with a low carbon base and filler metal. However, this method is not always useful for the stainless steel pipe and black steel pipe, because the carbon may be an essential ingredient in some applications. The second method is to control and minimize the time spend at temperatures which is conductive to sensitization as possible as you can. In addition, the maximum interpass temperatures should be adhered in welding procedures. The third, prevent the formation of chromium carbides with filler metals which includes special alloying ingredients.

Usually a back purge of argon is required by welding stainless steel pipe. In some applications, we can nitrogen which can be considered as a back purge to form some nitride compounds in the weld root to decrease the corrosion resistance. This is usually useful for stainless steel pipe to compress air systems and hydraulic fluid systems, and then the risk of corrosion can be lowed.

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