Boiler Tube Practice Stick Caps

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Been practicing 2-man stick welding caps onto a simulated pipe wall. Pipes are 2 1/2" outside diam. Spaced a loose 1/8" apart. Caps were ran at 90 amps with 7018s on a Miller XMT 350.Pics are of my welds only. Don't wanna go posting other people's work on the web and whatnot.I've been working on combination pipe for the last few months in class and recently pass for a 6" Carbon steel combo cert. I've got potential work after school and have been hard at it for the last few weeks. Any input suggestions or advice is always appreciated.
Reply:must be water wall practice? generally typical pipe spacings when it comes to membraned water walls is 1/2", I think the tighestest membrane portion of our boiler is our economizer which is 3/8". Then everything else is clipped or saddled like the primary and secondary superheater. Tig root? Your coming along for sure, takes a lot of time/practice to produce nice consistant caps especially in-situ. Just practice your consistency and youll be bang on my friend.
Reply:According to our instructor these are replicating steam lines running from the boilers in a papermill. Most of the work on this job is in an assembly yard outside the mill, but he has us practicing this all the same. Root pass and Fill were bot TIG, using 1/8" wire for root and 5/32 for the Fill.My mental debate with these caps is whip vs drag. I've been told that ideally stringer caps was what I need to work for. But incorporating a slight backwards circular motion allows me to keep the bead much more straight and the bead height more consistent.
Reply:Are you talking 1/8" space for your root? Like Pressure said I have never seen membrane 1/8".  Been in several small gas boilers in mills & plants and the smallest membrane spacing i have seen is 3/8".  Not trying to say i have seen everything or done all but just never seen that.  The plant i work at has the same as pressure 1/2" water wall in the main section & 3/8" in the back pass.I stand behind my welding, I just won't stand under it!
Reply:- Unknown,,nice to see a fellow boiler welder, I am on the maintainence side of things work at a generating station, unfortunately due to regulations our biggest boiler "unit 5" is the only coal fired unit left running as the old 1-4 units are smaller 33mega watt un efficient units haha. - fowlI may have miss read your post and like unknown said you may have been running 1/8" root opening? Also not trying to force any of my particular habits on you but I have never heard of whipping an 18 series rod especially on pipe. But that would explain the inconsistancies in your cap. Try running your caps with a nice forward progression and practice being able to rotate your wrist. Also if you have issue with keeping your beads straight try finding the edge of the bevel for your first pass as a guide, and then its gravy after that as you just follow your last bead. Maybe when I get back to work on Monday I can setup a "water wall" and demonstrate if you would like? But yes I would question your instructors knowledge on the spacings between the pipes, 1/8" is certainly not correct UNLESS their free hanging tubes which is old school boiler chracteristics. If the are free hanging water walls then you have the ability to use chain falls to spread the pipes apart quite a lot.... to the point of being able to do the whole weld yourself. You've chosen in my opinion one of the most highly skilled forms of welding out there so keep up the good work! only a boilermaker can relate to the whole new world of tight areas boiler welders have to preform xray quality welds in.Last edited by Pressure_Welder; 06-01-2013 at 01:47 AM.
Reply:There is a 1/8" root spacing but also between each individual pipe, but like I said its a loose 1/8" probably closer to 1/4". According to teach. the pipes can be wedged apart, so I'm assuming they must be free hanging. He used to be a boiler welder in his hay day so I don't question his knowledge or experience. I do appreciate the input from you fellas, nice to get some outside critiques from professionals in the field.@ Pressure, if you have the time id love to see a real water wall. But with requards to the motion, when you say forward motion are you talking about pushing the puddle rather than pulling it? I do use my bevel edge as a guide for the first cap, but I still have a problem keeping 2nd and 3rd to a proper spacing.
Reply:I like to do as Pressure does, use your lower bevel as a guide for your first stringer, I drag it as consistent as you can & after clean up I run a file on the uper edge of the weld leaving a nice guide for your next stringer & repeat until your cap is done.  They must be hanging tubes for a super heat section on their boiler.  I think I have some water wall pictures I can load for you.  Best thing is stay relaxed & get cumfy, you are gonna be welding in every position you could never think of & some real high places to.  If you can pull the tubes apart with a chain fall then I find it easier to put the root in myself starting on the back side, feed your wire threw the root to the inside of the tube with your arm & tig torch on the back side.  Its hard to explain but once you learn it its not that bad.  Pressure I work at a 250MW unit we still burn coal & so far dont look like any plans to change us to gas.  we have several small boilers on gas for heating or the damn paper mill.I stand behind my welding, I just won't stand under it!
Reply:here are a few Attached ImagesI stand behind my welding, I just won't stand under it!
Reply:- unkownhahaha last picture to me looks like pad welding being laid out after thickness testing! bleh we just finished 70' of pad welding on our corner tubes from the bottom of the secondary to about the 4th floor. Our unit 5 is 150 mega watts and we still burn on coal, unit eats up 80 tons an hr. Also have two combustion turbine units. Here are a few pictures from our last big outage, bit of primary work and secondary, always lovely places to be! primary has about 20" of room for us. Some pictures of the divisional walls on the 10th and 11th floors, operators had soot blower pressures cranked on a few so we had a lot of tubes 70 thou thick in places. Also we had a soot blower get stuck on the south west wall and stay open for 36hrs blasting a bank of about 10 tubes..... I am sure you know what that lead too ! Attached Images
Reply:- fowl.By forward progression I just mean to continue always forward I personally would never whip back into a 18 series rod in fear of slag inclusions plus I promise it would get rid of any sort of sag in your caps. Just picture overlapping your last bead by about 1/4 to 1/2, Maybe it might work better for you too, when working in tight spots like this I always shorten up on the rod because you really don't need the full length. Point the stinger face at yourself and bend the rod away from you over the head of the stinger and make sure its more or less flat against the head of the stinger, this will give you less rod "wiggle", and allows you to hold your hands closer to the pipe for better support, you should be able to make it around half the pipe fine this way. Also 90 amps is what I run all the time too, 100 amps for any downhand pad welding Attached Images
Reply:I recently picked up on shortening the rods and that did have a major improvement. I was having issues with porosity at my startups because the tip would wiggle to much before I got it stabilized. I usually put 2 bends in the rod and it seems to work well. Ill try working on my caps with no back motion on Monday and ill get pics up of the results after class. Thnks for the input and time guys.
Reply:Just a word about wall tube design.  As mentioned a wall could have 3/8 to full inch membrane.  To replace a stub you slit the membrane and totally remove it for about 2 inches in the area of the butt joints.  Another design is known as tangent wall where the tubes are tight against each other with no membrane.  To get enough clearance to weld in the tangent area, using wooden wedges and lead hammers, you reposition the tubes, in, out, in, out.  Both of these designs would be welded with one welder inside the boiler, the other out.  Must have been frustrating trying to tig the root with only 1/8 inch space between the tubes.  You might as well practice with a 1/2 to one inch gap.  Anything narrower is best left to the superstars.     As for the stick cap.  Usually this is done two welders working together.  A special 'y' is made up....one machine spliced with two stingers.  One welder welds into the tangent, the other meets him, the first welder breaks away and the second will become live and away he goes.  The first chips his slag and reloads to meet his partner at the opposite tangent.  Because there are no stop starts, there is less chance of porosity.
Reply:Old sparks we call that "buddy welding". On tangent tubes I like to use brass wedges, you can spread the tubes farther apart with no galling. I work in a large fab shop and we build all the coal fire boiler components.  Not many waterwalls with less than 3/8" as mentioned. Plenty of tangent tubes in superheaters, economizers, and reheaters. Division wall panels come to mind. Were the last of the true boilermakers.
Reply:I have always heard your "budy welding" called brother in law.  It was the same on some limited pipeline work i did as well.  Never saw this done with one welder & a special Y made, always two welding machines.I stand behind my welding, I just won't stand under it!
Reply:Originally Posted by unknownI have always heard your "budy welding" called brother in law.  It was the same on some limited pipeline work i did as well.  Never saw this done with one welder & a special Y made, always two welding machines.
Reply:Shadow that's basically what were doing in a nutshell. Splitter from the rig, 2 leads on 1 machine. The only difference is that we've been instructed to weld through the slag without taking time to chip it off.
Reply:We started another practice wall today, but only finished with ghee root and fill, so well cap it in the morning and ill post pics asap.
Reply:n the mean time hers a few interior pics of the roots, I know qualitly of the pics is poor but. I'm working with a cell phone so, yea..
Reply:Srry about the multi posts but I thought I outta point outbthat were buddy welding the tig portions as well. One guy runs the torch while the other feeds the wire around the "tangent" area. We do the root pass in quarter sections, joining them in the tangent. Then we run a 2 inch fill on both sides of said tangent. Afterwards is just a standard 1 man filler pass for the remainder of the gap.
Reply:Chip your slag or you'll be busting out.
Reply:How long have you been welding with the boilermakers? It takes time under the hood to become good. I like to run 4 passes for my cap. Usually slag welding depending on who my partner is. But now it's all plate mig building scrubbers for one of our plants.....it's so nice not to be in the boilerESAB MigMaster 275Miller Econotwin HFMiller Syncrowave 250
Reply:Are you asking me? If so, not at all, I'm still in school, but my last semester ends in 3 weeks. After that were heading north to begin working on a papermill.
Reply:FM....looks like you're off to a good start.  One thing about the method you're using to do the tig root.  Works fine with your partner feeding wire to the tangent but not always possible on a side wall.  It used to be the safety man looked the other way when the ventilation fans got turned down because air was getting sucked through the wall where you're welding and causing porosity.  Nowadays the fans have to be on. Different plants have varying policies.  The air is clearer in the boiler but  it's whistling through where you're welding.  In this case your partner will be busy blocking off the air flow.
Reply:Would a gas lense be beneficial in that situation?
Reply:Originally Posted by FowlMouthWould a gas lense be beneficial in that situation?Well Pressure, I took what you said into consideration and attempted to cap the next set using a drag method...it didn't turn out pretty. My travel speed was inconsistent, and the bead spacing was horrible. The tangent area transfer also got worse, likely do to the travel speed. I was focusing on rolling my wrist to keep the rod 90° into the pipe, but I think that's where I was getting hung up, putting too much thought into one aspect tends to negatively impact the rest of my technique. But there's always tomorrow.
Reply:Good job fowl, it will take time my friend as with any aspect of boiler welding. Like I say there are only a select amount of guys cut out for boiler work simply due to the horrible pipe locations and having you be required to still make xray quality welds, I know guys that can barely pass a 6g pipe test on an annual basis. I think all of us boiler guys on this particular thread can agree that you've got what it takes man. As for the drag method I would still continue this practice, as whipping an 18 series is not a great idea. Concentrate on the bead you should be overlapping your last pass by 1/4 to 1/2 the width of the last bead, and when it comes to you, the transition into the next bead should look almost seamless along with the same bead height. I would suggest maybe trying to run some horizontal beads on a piece of 3/8" plate. Maybe get a piece 10" square and practice pad welding and blending each pass in nice. I know this is taking a serious step backwards but once you get a feel for blending each pass in, then you can transfer that knowledge to pipe and youll know what your looking for, theres too much going on so fast on water wall pipe, or any pipe for that matter to not know exactly what should be happening. Haha trust me once you start replacing bundles and literally have 100 + welds to make itll become second nature and you wont even think about it anymore, your hands will just do what you need
Reply:Curious about what wall thickness these tubes are?  I understand coal burners have heavier wall but can only remember once stick capping in a pulp mill boiler.  Tig all the way.
Reply:Originally Posted by Pressure_WelderGood job fowl, it will take time my friend as with any aspect of boiler welding. Like I say there are only a select amount of guys cut out for boiler work simply due to the horrible pipe locations and having you be required to still make xray quality welds, I know guys that can barely pass a 6g pipe test on an annual basis. I think all of us boiler guys on this particular thread can agree that you've got what it takes man. As for the drag method I would still continue this practice, as whipping an 18 series is not a great idea. Concentrate on the bead you should be overlapping your last pass by 1/4 to 1/2 the width of the last bead, and when it comes to you, the transition into the next bead should look almost seamless along with the same bead height. I would suggest maybe trying to run some horizontal beads on a piece of 3/8" plate. Maybe get a piece 10" square and practice pad welding and blending each pass in nice. I know this is taking a serious step backwards but once you get a feel for blending each pass in, then you can transfer that knowledge to pipe and youll know what your looking for, theres too much going on so fast on water wall pipe, or any pipe for that matter to not know exactly what should be happening. Haha trust me once you start replacing bundles and literally have 100 + welds to make itll become second nature and you wont even think about it anymore, your hands will just do what you need
Reply:Man you got a good start. I agree with sticking to the drag method. Try some esab rods they are my favorite 7018 rod. If we could use Kobe 7016 that stuff is the cats a**. use it for open root lohi welds. Keep up the great work you are only lacking hood time. Once your hand gets in it you will be happy with the results
Reply:Lot of weld for 1/4 inch wall.  I was thinking it was over 3/8".  Still it's good to practice on.  As for stacking the three passes......I'd suggest a stringer on the bottom, a little counterclockwise circle for the second pass to build up a higher profile, and a quick stringer on top to balance the convex profile.  Knocking the slag off between passes helps see your bottom line.   Never tried stick welding into such a tight tangent though.  Any suggestions?Last edited by OldSparks; 06-04-2013 at 10:29 PM.
Reply:It's a tube guy's not a freaking pipe, lol.
Reply:Well day 2 of the stringer caps today. Progress is being made. Were turned the amps up from 85 to 91 and it seems to help a bit with the consistency on the bead height. Still need to workon the tangent area transfer and spacing, but overall im pleased with today's practice.
Reply:Good work there. Keep it up and youll be a tube welder in no time. Now start practicing the convection box test.
Reply:Weld tech would buy those caps off anywhere I've worked. Could it be more consistent? Sure, but it still looks good. Time under the hood is all it takes. Keep at it and you'll lay those caps perfectly straight. I'm still a fan of four passes for a cap but that's me.ESAB MigMaster 275Miller Econotwin HFMiller Syncrowave 250
Reply:with water wall tube only being close to 1/4" thick theres absolutely no need for a 4 pass cap, we do it in two here at our station. superheat tubes are closer to 3/8's so we throw 3 on those. Steam loop on the turbine.... haha we throw about 15 cap pass's on those. although its 1 - 3/4"  J- Bevel 8"
Reply:Originally Posted by Pressure_Welderwith water wall tube only being close to 1/4" thick theres absolutely no need for a 4 pass cap, we do it in two here at our station. superheat tubes are closer to 3/8's so we throw 3 on those. Steam loop on the turbine.... haha we throw about 15 cap pass's on those. although its 1 - 3/4"  J- Bevel 8"