Stainless Steel Pipe Fabrication
To be able to make high quality joints that are to be installed in between cylindrical sections made of stainless steel which includes pipes, containers, and tubes, the atmospheric gas must be eliminated. If ever there is oxygen and some nitrogen present around the part being welded, a number of defects may arise in the future. These defects include discoloration which can be a horror to the eyes which can also lead to there being an imbalance in the metal composition that is common with stainless steel, gross oxidation which in turn reduces the mechanical properties of the joints which makes the corrosion resistance weaker and nitrogen contamination which will make the parts brittle. If there are any gases within the area while it is being welded, chances are the area may experience cracking when it starts to cool. This is particularly important to note especially in pipe bending fabrication.
To ensure that the weld root is of good quality when welding on tubular joints, there should be the proper safeguards that act to help remove any atmospheric air around the area that is being welded and promotes inert gas going onto the fusion zone. The process needed to do this is known as gas purging.
The purging gas that is commonly used in Europe is argon that has a commercial quality. The United States settles for the cheaper helium gas. There are special cases in which the purging gas being used are mixtures of argon and hydrogen, helium and argon and other developed gas mixtures. Industrial construction companies use those mixtures.
There will be a number of considerations when choosing a gas or gas mixture for a certain weld. Some of these considerations include the welding process that is being done and the materials that are being attached together. The flow rate of the purging gas and the pressure has to be set and after selection must be integrated into the whole procedure of welding.
When one is welding the parts, there is a chance that the quality of the purging gas will experience variations. Because of this, it is recommended that the purging gas should be monitored not only to keep an eye on the quality but to control the amount of moisture and oxygen gas that seeps in as well which would otherwise affect the quality of the purging gas.
When attempting to do a gas purge, there should be points where the gas can enter and exit. The gas goes through one seal while at the other end is an exit hole. This serves to prevent pressure from building up too much while purging. If the purging gas being used is argon, then the exit end should be lower due to the gas being denser than air.
Since the internal volume inside small tubing, the cost of doing a continuous purge all throughout may not be a big a deal. If one were to be in these circumstances, you may opt to tape the ends with discs made of wood or plastic. Plastic caps may be used so that the ends of the pipe will be protected after the pipe fabrication.