i want to learn to weld...

[GHarman]

Socket Welds on Pipe, FYI

Anyone out there doing socket welds on pipe? The rule of thumb, a minimum fitup requirement,(Specified on a WPS), there needs to be at least 1/16" ( a larger gap with thicker wall and larger diameter)clearence between the end of the pipe inserted into the socket fitting and the bottom of the female portion of the socket fitting. If the pipe is bottomed out in the socket fitting the weld can crack as it cools (hot cracking), at the least the weld can fail under use.

Why? From a laymans standpoint, the weld, as it cools pulls the pipe down towards the weld which also pulls the pipe into the socket. If it is bottomed out, a stress load on the weld is created that exceeds the tensile strength of the Filler metal & base metal in its cooled state. GregH

 

[DJW]

GregH, does socket weld, mean using a Back-Up ring between the two pipes? I believe they were open circle with a number of pins spaced on it. Seen very few used because if certifying using them, only certify with use. Using them fitting up, did help lining joint. (need all the help one could get!) If I remember correctly on some weldments it was customary for the first weld to crack, but it was ignored and welding carried on over it, I always questioned it, and suggested to air arc a grove, not necessary to remove the original weld, just eliminate the crack, but the engineer told the welder to weld over it. I was also told stainless could be used, and was used by many especially if water or moisture involved. Seems on each job one works on more knowledge is gained. One time I was sent to weld a 3" x 18" x 18" square of well weathered steel to overhead beams, it was used to seismograff (sp?) for earthquake stuff, instruments were attach (all High Tech. Stuff) They asked for just 3 inches of weld bead six of them around the perimeter. I cautioned, that I believed just one single bead was chancy for the size and condition of the plate, plus without pre-heat I expected the first pass to crack. I suggested the 3" should be three passes, as they would be working under it, (it couldn't be tied off for safety) but they assured me just the singe bead 3" long in six places around the plate. When I got back to the shop I told my employer of my concern, so as he would not be responsible for any problems. I have found many engineers, in fact too many, need much more field experience, what works in the Lab, often has little bearing to field conditions. One I suggested to try some light heat, replied that it would take the TEMPER out of it, the steel in question was MILD STEEL.

 

[GHarman]

Socket weld fittings

DJW, Fittings can be a Coupling, Ellbow or a Tee or even a valve body. They have a counterbored I. D that is very close to the O. D. of the pipe and have a controlled depth(shoulder inside). I have found these used on Steam Stations on either side of a trap and on some Stainless Steel applications. Why they are used? Probably 'cause there is not a need for a precision fitup and can be "cut in" easily where the pipe is rigid. With 4 sockets (two fittings) on a "cut in" there is 4 places to fudge length and there is no purge requirement.

On mild steel; I like a minimum preheat that drives off the moisture. You can see it evaporate off the surface. A propane weed burner works great. I believe that there is a 100*F. /inch of thickness rule of thumb flying around there somewhere. GregH

 

[DJW]

GregH, thanks I understand now, say where a sch. 80 pipe will slip inside a like sch. 80 valve. That's the only time I ever used slip on for pipe,I never used couplings, elbows or tees, or even seen them to recognize them. I always questioned the use of threaded sch. 80 pipe when the threads cut deeply into the thickness of the pipe. Claimed a welded sch. 40 pipe line equals a sch. 80 screwed coupling pipe line. I had a Black helper who would distort a sch. 80 coupling working off a vise on a one ton, often wondered if he'd turn the truck over. I corrected him where to place the pipe wrench, and to just snug a threaded coupling into open end of pipe before tightening coupling.

 

[GHarman]

Almost, Constant O.D. vs Constant I.D.

DJW, You got the right idea, just the dimensions backwards. A schedual 80, 2" pipe is the same O. D. as a Schedule 40, 2" pipe. O. D. remains the same on Pipe sizes until you get to 14" If I remember correctly. Then the I. D. is constant and the O. D. Changes. GregH



PS, A socket is not the same as a slip-on such as a slip-on flange. A slip-on flange is welded outside and inside and is bored straight through.

 

[GHarman]

Schedule vs # Rating

DJW, I probably misunderstood your answer. The Valves and flanges are rated by pounds as opposed to wall thickness. Example 175WOG or a 400WOG. (Water, Oil, Gas) stamped on a valve and just the Pound rating on the rim of a flange such as 300#. There are specialty valves also made of different materias such as S. S and Hastelloy that are also rated by pressure. Just some thoughts. Dave Valentine could speak more directly on this subject as he is still hands on in this area. GregH

 

[DJW]

GregH, yes we used to identify the flanges by the number stamped on them, but had no idea of pressure, just told what to use, the forged flanges we called 'Weld Neck' because they were designed to be welded because of the 'Neck'. Of some valves it would be depending on flow, 'in at the top. out at the bottom'. The slipon flanges being mild steel had to be welded using stainless steel rod, owing to chrome molly pipe,and the inside weld as the acld fluid would be in contact with it. Working near a pressure reducer, (told it was. as not aware of it's purpose) it exploded blowing out one ribbed side, seems pressure had been released on one side, and build up on the other unable to equalize. It was a sulphuric acid line so we were lucky not being in it's line of fire. It was only the residue so to speak and not flow. May of those plants can be dangerous to work in. Told in time of trouble to run into the wind even if through a cloud, as that was the only chance of escape.

 

[GHarman]

Yep, Lots of different applications and materials. Weld neck, slip on, socket weld, threaded, Compression, flanged, ferruled. Probably some I fergot and some that I havent even heard of. GregH

 

[DJW]

'The Great One' seeks help, ('Needing Help, but Please keep your Smart remarks to yourself'). (Ho. Ho. Ho. ) using a Miller 210 Mig, on starting to weld, wire snaps off at tip. Changed tip, (tip correct size) wire roll runs free (light) no heavy drag, tube from feeder rolls clean. Tube exiting from machine not abrupt bend, in fact supported to exit in a straight line. If pressure at feeder rolls tightened bird nest results. Roll pressure adjusted as per Millers VCR tape. Adjusted current controls as per chart, plus adjust each side of figures to try and eliminate problem, gas adjusted as chart, flowing free, so no problem there. Regardless of tip to work distance, problem remains. Wire coating clean in good condition, and being in cabinet not subject to undue dust etc. A few years ago the ESAB done the same to me, (in New York, so no electric supply problem) but never solved it as gave machine to son, and he never had that kind of trouble with it, so I doubt the machine at fault. Quite a problem, as yet not reduced to Tears, but getting very close. Swearing, and or, Praying of no help, so not resorted too, no prize offered, but Boundless Praise and thanks for successful solution. (that should be Reward Enough! think about it) Thanks

 

[GHarman]

Bend allowances

In post 456, I asked about bend allowances. Having packed everything away, today I was able to find and review my information. It is not reproduceable by any means I have and it is quite old. No matter, We have the internet. So I did a little search. Here are some results that may be useable for any of you that are in need. I have no way to verify these. Use test pieces before commiting job material. If you have better resources, please post it if you are able. GregH



determining sheetmetal bend allowances

Bend Allowance Verifier

 

[GHarman]

'The Great One' seeks help, ('Needing Help, but Please keep your Smart remarks to yourself'). (Ho. Ho. Ho. ) using a Miller 210 Mig, on starting to weld, wire snaps off at tip. Changed tip, (tip correct size) wire roll runs free (light) no heavy drag, tube from feeder rolls clean. Tube exiting from machine not abrupt bend, in fact supported to exit in a straight line. If pressure at feeder rolls tightened bird nest results. Roll pressure adjusted as per Millers VCR tape. Adjusted current controls as per chart, plus adjust each side of figures to try and eliminate problem, gas adjusted as chart, flowing free, so no problem there. Regardless of tip to work distance, problem remains. Wire coating clean in good condition, and being in cabinet not subject to undue dust etc. A few years ago the ESAB done the same to me, (in New York, so no electric supply problem) but never solved it as gave machine to son, and he never had that kind of trouble with it, so I doubt the machine at fault. Quite a problem, as yet not reduced to Tears, but getting very close. Swearing, and or, Praying of no help, so not resorted too, no prize offered, but Boundless Praise and thanks for successful solution. (that should be Reward Enough! think about it) Thanks

DJW, What kind of condition is your wire guide/ liner inside the hose. It looks like a long spring. If it is hanging up, because of accumulated crud or kinked? The voltage will pinch off the wire at the tip when the wire feed speed hesitates. The mild tightening of the drive rolls causing a birds nest suggests you got a liner problem. Another thing that will get even the most experienced weldor with a GMAW is kinking the wire guide/liner (too sharp of a radius) while welding in a bad position. Have you considered any of these possibilities? Hope this is helpful. GregH

 

[DJW]

DJW, back again, thinking of buying a Plasma Arc for cutting. Have not bought one for years so not aware of all the advances made, ie 110-220 volts, easy start, etc. (although never found that a problem). Improvements are rapid these days, so perhaps all makes and models have the same improved features. Up to 1/2 in steel adequate. Checking some machines, also list minimum thickness, ones I used cut from very thin, (technical term) to optimum thickness for clean controlled cut. One I used, same machine and setting for 3/8 stainless and gauge, excellent cuts, one of the finest tools placed in a metal fabricators hands. (and getting Paid an added bonus). The prices seem very reasonable for general shop work, (buy while prices are low?) Would prefer American made, Miller seems a reliable product, and we all need Americans working. All recommendations welcomed. Thanks

 

[DJW]

GregH, thanks Greg, had thought of that, welder fairly new, but of course could have accumulated dust and junk. When I had my business if I had trouble with the tube liner, just bought a whole new hose and torch, now have time to check liner. I did check weight of pull with my son's spare one here, and pull force seems equal, but of course much different than when welding, checking pull weight with the tube in a straight line much different when angled when welding. Thanks I will withdraw liner and check. (be careful avoid watching the ARC especially when not wearing a hood) On TV did seen Africans in Africa arc welding just using goggles, seems the general practice there, as no one was using hoods or shields.

 

[GHarman]

Sun Burn

DJW, I hope they were using SPF-100 Sun Screen. Man, I'll bet they got burnt. Years ago, one of my students was working at a local "sweat shop" as a tacker with the GMAW. He was just turning his head as he tacked. He looked like a boiled Lobster! Boy, did I get into his face#@$%!. GregH

 

[DValentine]

I agree with Greg, on replacing the liner of the wire feed. I have not spent months running them, but the little I have run them, the liners have caused problems. It is an easy swap and good piece of mind. The way you describe the birds nest, when you tighten the drive rolls. Another one is having the drive rolls on the wrong wire size.

D

 

[DJW]

DValentine, I did check to see if I could remove the liner, removed both ends but unable to withdraw the coiled wire inner. Ran the wire I clipped off the roll to feel for any hang up but quite free. Remembering the ESAB, that done the same to me, and was only about 3 months old from new, and this Miller seen very little use. Wire on roll bright and shiny no dust. There is not any other electrical tool or equipment in service, so no spikes in current. I thought there was a nylon inner tube in the coiled wire, but it must be just a steel tube and no nylon core. As mentioned, I checked draw of wire free from tension of rolls alongside my son's machine and both took the same weight of pull. Rechecked wire size of feed squeeze rolls, both reading . 030 as viewed as per instructions, and size on wire supply roll reads . 030. (one has to check everything, and the usual new wire tip. ) It is vexing (note High Class wording) when one feels the whole World is against one, (could even be) (wife warns me constantly) Re. the ESAB I asked my son if he had experienced the trouble I had, and he never found it. (it is something about machines you know) If employed, it's so easy to ask a fellow weldor to adjust, and or check your machine for you, I've had young weldors almost in tears asking for help, I'd tell them not to worry, as it can happen to all at times, and asking for help certainly does not diminish respect. Just come to me, remembered when a weldor was having trouble and asked for my help, I couldn't fined the cause, until I told him to weld, then saw his ground clamp was arcing, cleaned contact surfaces plus part where clamp was clamped and eliminated the problem. (that's the one thing I didn't check) must give it a try. Thanks for all the tips.

 

[DValentine]

I go back to the wire tension on the drive rollers. Why would it birds nest unless it was pushing against something up "stream" in the liner. There may not be a piece of wire stuck in it. It may be that when you put it in weld position that something changes, in comparison with just running wire through it by hand. You have me stumped..... like magnetism in a header we were trying to weld.

Some days it doesn't take much for me to run against the wall of ignorance.

D

 

[Coalsmoke]

At what point exactly are you having the filler wire break? Immediately before the contact tip? In the neck of the gun? Immediately exiting the contact tip?

 

[Coalsmoke]

DValentine, I did check to see if I could remove the liner, removed both ends but unable to withdraw the coiled wire inner. Ran the wire I clipped off the roll to feel for any hang up but quite free. Remembering the ESAB, that done the same to me, and was only about 3 months old from new, and this Miller seen very little use. Wire on roll bright and shiny no dust. There is not any other electrical tool or equipment in service, so no spikes in current. I thought there was a nylon inner tube in the coiled wire, but it must be just a steel tube and no nylon core. As mentioned, I checked draw of wire free from tension of rolls alongside my son's machine and both took the same weight of pull. Rechecked wire size of feed squeeze rolls, both reading . 030 as viewed as per instructions, and size on wire supply roll reads . 030. (one has to check everything, and the usual new wire tip. ) It is vexing (note High Class wording) when one feels the whole World is against one, (could even be) (wife warns me constantly) Re. the ESAB I asked my son if he had experienced the trouble I had, and he never found it. (it is something about machines you know) If employed, it's so easy to ask a fellow weldor to adjust, and or check your machine for you, I've had young weldors almost in tears asking for help, I'd tell them not to worry, as it can happen to all at times, and asking for help certainly does not diminish respect. Just come to me, remembered when a weldor was having trouble and asked for my help, I couldn't fined the cause, until I told him to weld, then saw his ground clamp was arcing, cleaned contact surfaces plus part where clamp was clamped and eliminated the problem. (that's the one thing I didn't check) must give it a try. Thanks for all the tips.

To remove the liner on your M series gun (assuming you have the OEM gun), remove the contact tip, completely disconnect the gun cable from the machine, lay it out straight on a table or the floor, unscrew the liner inlet tip which is the part that is attached to the liner at the power source end of the cable and then pull out the liner. It is removable and next to the contact tips and diffusers, is the next regular consumable item. It sounds like your liner might be a bit short on you or broken, you want it protruding at least 3/4" out the neck of the gun. Liners can be broken / squished especially when rolled over with hard caster wheels.

 

[GiesJ]

DJW, You got the right idea, just the dimensions backwards. A schedual 80, 2" pipe is the same O. D. as a Schedule 40, 2" pipe. O. D. remains the same on Pipe sizes until you get to 14" If I remember correctly. Then the I. D. is constant and the O. D. Changes. GregH



PS, A socket is not the same as a slip-on such as a slip-on flange. A slip-on flange is welded outside and inside and is bored straight through.

A couple things - All piping maintains constant OD. 14" NPS and up has the pipe size = to the NPS (nominal pipe size). Meaning 18" NPS pipe is 18" OD regardless of schedule. Under 14" NPS and the size is 'close to' the NPS. Example - 4" NPS is actually 4. 5" OD.



Good point regarding socket welds vs. Slip-on flanges. A slip-on flange sees a double fillet (that will only handle shear) while a socket is only a single fillet, completing the socket weld. From my experience, I have never seen any socket weld fittings over 2. 5" NPS (that's 2. 875" OD in case you are wondering!) Most often, in high quality applications with lots of non-destructive examination requirements, you will see weld neck flanges spec'd so that the weld is full pen and can be RT or UT'd.



jason