Everyone, take a look at this tricky issue regarding the welding of the take over to the cylinder
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Our factory has undertaken the production of a batch of stainless steel jacketed equipment, with a cylinder wall thickness of 12 mm and operation at atmospheric pressure. The client requested that sanitary-grade pipe fittings connected by clamps be used; the wall thickness of these pipes is around 2 mm. During welding, blackening of the inner surface of the pipes occurred, along with the formation of slag, as shown in the image below. Could anyone help analyze what might be the cause of this?
Could the original poster describe the situation in more detail?
That’s right; all our equipment is made of stainless steel with a wall thickness of 12. The customer required that sanitary-grade quick-connect fittings be used. After purchasing them, it was found that the holes in the end caps were a bit too large. There was nothing we could do other than use TIG welding. Due to the thin walls of the tubes, the inner surfaces turned black and slag formed on them. Some of the tubes were also deformed. Since these were holes in the end caps, it was difficult to apply argon protection during welding, so no argon protection was used
2mm is too thin. What is the diameter of the pipe opening?
Are all pipes from 25 to 100 mm thick at 2 mm? I really don’t understand welding. But I can remind the original poster to describe this issue in more detail. Cylinder diameter, material (ferritic stainless steel or austenitic stainless steel?) ) The electrodes used for welding, the welding current, and so on – this makes it easier for those who truly understand welding to assist you. As a side note, can a 2mm thick tube meet the requirements for reinforcement through drilling? Also, what is the standard for the sanitary-grade pipe fittings purchased? The original poster can provide more details
Welding sanitary-grade pipes is completely different from welding regular pipes, you know. . . Argon flushing inside the tube is the most fundamental step; how can welding be done without doing this? Here’s a website for you to take a look at: https://wenku.baidu.com/view/70e20cc9284ac850ad024288.html.
It seems like the current level is too high; it’s even causing penetration during welding.
OP! I’m going to say something; please don’t get angry! Given the condition of the solder joints in your photos, tell this welder to go home! Otherwise, it will ruin your factory’s business prospects!
Argon shielding must be provided on both the front and back sides during TIG welding. The blackening inside the tube is due to inappropriate parameter settings; the current was too high, causing breakdown. Use argon protection well (have someone on the back side use argon for protection), and try using a thinner welding wire. Additionally, the area around the weld joint should be cleaned to 25 mm.