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Inside-corner welding is one of theose situations where the torch tip can overheat, and you get pops. Sometimes the flame then blows out, too. With a T-Joint there's lots of opportunity for popping, especially if it's a long joint (say a foot or more), because the bead being lengthy the torch tip gets plenty of time to heat up a lot.Higher gas pressures seem to reduce popping, but also seem to mean you can burn away the parent metal more readily - even if you avoid an oxidizing flame. Sometimes getting a hole or nearly so.Do you think that a solution may be to use a larger-than-recommended tip, so that you put more heat sooner into the joint? I'm thinkng you can keep the tip a bit further from the steel, and also that maybe you can move along quicker this way.(By "larger than recommended" I mean larger than the torch company tells you is needed for a given thickness of steel stock.)
Reply:The tip overheats and that is the cause of the popping. I find that if you duplicate the angle of the torch tip by holding the handle inline with the joint you will not get heat reflecting back at the torch tip. You don't always have to hold the torch in that awkward manner but just duplicate the angle. Yes increasing the size of tip or intensity of the flame will allow you to slightly move the torch back away from the puddle. If you find yourself wanting to put the tip in closer and closer possibly your flame is too small. I find that most people who have popping when using the correct tip are holding it at the wrong angle. In other words the heat from the flame is rebounding off and heating the tip. The heat should be thrown down and forward or down or backward if you are doing back hand on heavier material.
Reply:Yes to a larger tip sometimes but a joint of a foot or more? Break that up into some shorter skip welds. If you try to do that in 1 shot your going to end up with way too much heat in the joint. It's going to warp like crazy.Tough as nails and damn near as smart
Reply:tresi, nailed it. short welds, backhand, backstepping, etc. are all acceptable. I tend to back hand more on a t joint due to that very reason. I tend to run the smallest tip I can get away with and turn it up. the higher flow will help keep the tip cooler than if you run a larger tip and turn it down to keep from blowing a hole.I don't normally weld larger stock with O/A. Most of what I do with O/A welding is delicate stuff or thin material.
Reply:Hey, this is a cool threadI don't do any Oxy welding, but do a lot of heating.I was getting a lot of popping with my rosebud, talked to someone that knew more than me, and he said it all boiled down to flow rate. If the flow rate is insufficient to cool the nozzle/tip, it would overheat and cause the backfire.Now when heating with the rosebud I tilt the tip to an angle to keep it from blowing directly into the metal I want to heat. Takes a little longer to reach the desired heat, but it eliminated the POP and death of the flame."Any day above ground is a good day"http://www.farmersamm.com/
Reply:seems like a rosebud has a higher acetylene requirement than anything else(cutting or welding tip) and has a better chance of popping because the high amount of gas is not being provided..
Reply:Originally Posted by weldbeadseems like a rosebud has a higher acetylene requirement than anything else(cutting or welding tip) and has a better chance of popping because the high amount of gas is not being provided..
Reply:that large #5 will out heat a cutting tip any day. It will in most cases out heat a small rosebud.
Reply:A #5 welding tip puts out 35 ASCFH. The #4 rose bud puts out only 20 ASCFH. The #6 rose but steps up to 40 ASCFH.The welding tip will be much more concentrated in its heat so you will have to move it around a little more so you won't scribe your metal. You can literally write you name in the surface of the metal with the flame of a welding tip. The same can happen with a larger rosebud, but instead of one flame writing you have several.While in this discussion of heat. What size tank are you using? Take the Cubic feet and divide it by 7 and that will be the maximum size tip you can use. So for instance, if you have a 110 cubic foot acetylene tank, the maximum withdrawal you can have is 15.7. The #5 tip would be too big for your tank then. You would need to get a bigger tank to be safe.
Reply:I guess I'm lost in the numbers, different tip numbers for different manufacurers.A small tip will deliver an amazing amount of heat to a small area.Up front apologies to the OP I have a tendancy to take the acetylene thing into either heating or cuttingBack to small tips, and concentrated heat.Yeah, it will deliver the heat, but the soak time is the problem. You can heat a small area to the melting point, but if you're dealing with a relatively large area.............. the time to heat the core spot, and the time to spread the heat over a wide area defeats the purpose. By the time you move the torch over the wide area with a small tip, the heat in the start point has dissipated. It's sort of like a dog chasing it's tail.Acetylene, unless the bottles are manifolded, delivers a small flow rate, insufficient to cool a large head. It's the reason I've switched to propane for big heating jobs.Y'all are gonna see some weird posts from me for a while, still not settled down. I might get a little aggressive, but it ain't personal."Any day above ground is a good day"http://www.farmersamm.com/ |
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发表于 2021-8-31 23:39:54