Q & A details - Plug welding holes then drill and tap them?
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Plug welding holes then drill and tap them?

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Just wanted to talk about welding I got the fever.Ok so we get these BOP (blow out preventers) and the threads are trash I was thinking how are we going to fix this, dads says plug welding.So he shows me what to do really hard at first, but now after about 50 holes of this stuff I got this looking good or way better at least.Anyhow you guys think plug welding holes is hard when you know they are got to be machine out no bridges gaps etc in the weld.Excited tommorrow to see how my weld turn out when I drill and tap it, so yah I got the fever.
Update: drill and tap came out really good I get off doing this stuff.
About the slag their is none you knock it out, then weld again little at a time and again etc.We heat the material up before we weld on it, so it's not hard when machine out.The right temp is when I spit on the material and it sizzles then I go ahead and weld no breaks or anything 6 hours straight welding.
Yes I drill out the holes with the threads trash about a 8th bigger, you can do it without drilling it bigger, but it's harder and not going to look right casue of the groves in threads make bridges and gaps in the weld. 

Other answers

  • 0861788249

    0861788249 2017-01-22 11:01:19

    It depends on the diameter of the hole and how deep it is. I have done that at work a couple times and made it work but here is some problems you might run into 1. When you heat metal up to melting point, all the carbon in the surrounding are rushes to the weld making it stronger and harder. This will affect all the surrounding material as well because now you have different carbon levels in your part so in the future cracks may start to appear in the part( could be months or years) 2. Machining through welded material sucks balls. just turn your RPM down 1/3 of what your were previously running. tapping it is even worse. taps break very easily. i don't know how you plan on tapping them but i would do it by hand. a tap-o-matic would just mess it all up. 3. depending in the part you are making the surface of the part may have to be machined again to compensate for the part expanding, contracting, warping, etc. P.S. in case you didn't know the formula for calculating RPM on a lathe, mill, or drill press is CS X 4 divide by the diameter of the tool. The CS stands for cutting speed which you will have to get a chart that says the cutting speeds for different materials. i happen to remember that the cutting speed for 1020 steel is 100. so 100 x 4 = 400. now lets say its a .187 drill bit. so you would go 400 divide by .187 giving you 2139. and bam you have the maximum rpm for that material.

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