Why and how to gas purge stainless pipes. TIG welding
Why and how to gas purge stainless pipes. Hello, everyone. Today we are talking about stainless pipe “Gas Purge.” When welding stainless pipes, it is common to create a gap between them and weld them. The outside of the pipe is protected by “Shield Gas” from the nozzle. However, the inside of the pipe is not protected by “Shield Gas.” This is carbon steel. Welding through gaps will not protect the back of the steel plate from shielding the shield. I’m going to weld this. Carbon steel does not oxidize even the back of an iron plate that is not directly protected by “Shield Gas.” However, if the stainless steel plate is welded in the same circumstances as before, the welds protected by shielding gas from the nozzle are normally welded. But the back of the steel plate without shield gas is exposed to the air. And the flowers that are oxidized bloom In the same situation, we will weld stainless steel plates. Welding area protected by shielded gas is normal. However, the back of the iron plate blooms with oxidized flowers. The same is true of stainless pipes. The inside of the pipe is not protected by shielding shielded gas from the nozzle. We will also try to weld the outside of the pipe. As you can see, the outside of the pipe is not oxidized. The inside of the pipe is a oxidized flower. However, there are some exceptions. Storage containers without pressure, structural pipes, vacuum lines with low pressure, sink, refrigerator, etc. In some cases, it may not be fully penetrated and welded. In such cases, welding is often done without “gas purge.” This depends on the company’s regulations or on the customer’s request. Now let me show you how to gas-purge and weld the inside of the pipe so that it doesn’t oxidize. First, “Tack” did it this way. Please note that one of my videos is about how to “Tack” the stainless pipe. First, connect the gas canister to the hose. You can inject gas into the pipe using a hose. At the end of the hose, I cut off the finger of the glove and attached it. Failure to do this will result in a “Wandering phenomenon” inside the pipe, as the gas is sprayed directly from the hose. That’s why I cut off the fingers of the gloves and This gently injects the gas into the pipe. You can use paper tape to connect the hose to the pipe. You can use this sponge. The thicker the sponge, the better the airtightness. This is how you connect the hose to the pipe. And then you inject it with purgis. This is what the pipe looks like inside. The opposite side of the pipe must be blocked from leaking gas. You can use a sponge to block the pipes. You can use paper tape. And there is a way to use glass tape. It is also recommended that you block between the two pipes. You can use a glass tape. Paper tape has better adhesion than glass tape. If you have a lot of money, you can use it a lot. This injects the purge gas and pulls the air from inside the pipe out. I’ll show you two ways. Purgigas are commonly used for algon gas or nitrogen gas. Since argon gas is heavier than air, it is filled from the bottom of the pipe. In contrast, nitrogen gas is lighter than air, so it is filled from the top of the pipe. For example, argon gas is filled from the bottom of the pipe. The air inside the pipe is then pushed by the argon gas and removed from the top of the pipe. The argon gas must be injected and the oxygen inside the pipe must be removed There are two ways. Please open the 12 o’clock tape. This will remove lighter oxygen than argon gas from the top of the pipe. To remove oxygen, drill a “Vent” hole in the top of the pipe. This removes oxygen from the top of the pipe. When purging with nitrogen gas, you can do the opposite. Nitrogen gas is filled from the top, so you can drill the Vent hole at the bottom of the pipe. Here’s how to make sure the inside of the pipe is purged well. You can also use a thin stainless steel plate. Or you can use a stainless spoon. Lift the iron plate between the gaps and weld just a little. If “purging” is successful, the back of the iron plate will not oxidize. If it’s not Purge, this is what happens. The back of the steel plate is oxidized to a gray You can check the purge gas pressure with your fingernails. You can use your lips when it’s hard to check with your fingernails. Because lips are thin, you can feel weak wind easily. It’s enough to feel the wind coming out of the gap of 12 o’clock when you check the pressure of the purge gas pressure. I’m going to show you the difference between welding with a lot of tape open and welding with a little When welding with a large amount of tape open, oxygen may seep through the gaps. The back-bead will then show a color other than white. So this is a different color. If “acid treatment ” or “electrolytic polishing” is performed after welding is completed, it does not necessarily have to be white. If it’s not oxidized, it doesn’t matter if it’s gray. However, the pipeline that does not post-processing after welding is recommended to come in white. It’s just for reference. The reason for this gas purge is to remove harmful gases, oxygen, vapor, etc. from the weld area. And the “purge gas” used is a lot of argon gas, nitrogen gas. Depending on the situation, mixed gas or helium gas can also be used. And there are materials that are not allowed to use nitrogen gas depending on the material. However, nitrogen gas has the advantage of being cheap. As such, the “purge gas” used depends on the welding situation, material, and price. It’s just for reference. So today, there are people who are curious about how to “purge,” so I made a video. I hope this video was helpful. Today I’ll finish with this. I’ll be back with another story next time. Thanks for watching.