My day at work, power station boiler wall

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G'day all, I thought some of you might find this interesting, this is a 550 mw power station boiler.Internal boiler scaffold, this is the top section of the lower boiler scaffold, 8 stories tall from the internal deck i'm standing on, the deck is 3 stories from the bottom of the boiler.Lower section of the scaffold, few tonnes of quick stage in herewelding machine I'm using today, fronius transpulse synergic 2700.On this outage, we've been replacing boiler tubes that have gotten to thin on the bends, new tube is 6mm, service limit is 3.5mm before needing replacement, tube blow-outs start to happen at 3mm.Tubes at this point in the boiler are B2 Cro-Mo (1.25% chromium, .5% molybdenum), Tig welded at around 130-160 amp's with DC lift start.Today, I'm covering the 'mouse holes' in order to seal the boiler, my TA holds a piece of Cro-mo flat bar on the outside of the boiler while i tack it in placeWhich are then welded with Tig at around 160-180 amps, notice the gaps in some of them, this can get fun if your not quick enough with the wire!Once the mouse plates are welded, prep the fin plate for welding by grooving them with a grinding disk on a 5 inch angle grinder, these are back ground from the other side to make a full peno weld.Then welded with the Mig running B2 Cro-Mo duelshield wire, and 18% Co2, 2% oxygen 80% argon gas, at around 23 volt's/190 amps.A few interesting fact's about the boiler.-Boiler is 20 stories tall-Produces 3 million pounds per hour of super heated steam.-Steam at superheater outlet is 550 degree's centigrade (1022 F), and 2'600 psi of pressure.-the boiler consumes 600 tonne of coal per hour, or nearly 15'000 tonne per day.-Main steam lines going from boiler to turbine are 700mm internal diameter, 150mm wall thickness, two lines per boiler.-Steam turbine produces 737'000 horspower at 3'000 RPM, producing 1.3 million f/lb of torqueLast edited by ttoks; 04-12-2014 at 03:21 AM.
Reply:Thanks for the picas, very interesting indeed. I can't imagine the contortions you have to go thru to weld some of those pipes. Is there any kind of test, x-ray, ultrasound or .... done on the welds? When you say 20 stories tall, is that the height of where the actual fire is, the firbox I guess you'd call it. Burning coal I would assume it's not the cleanest place to work in yet it doesn't look too bad, relatively speaking that is :-), how is it cleaned?. I work around construction equipment/structural my life so this is totally new to me, closest I've been to a boiler is welding the structural decades ago.....Mike
Reply:Originally Posted by mrmikeyThanks for the picas, very interesting indeed. I can't imagine the contortions you have to go thru to weld some of those pipes. Is there any kind of test, x-ray, ultrasound or .... done on the welds? When you say 20 stories tall, is that the height of where the actual fire is, the firbox I guess you'd call it. Burning coal I would assume it's not the cleanest place to work in yet it doesn't look too bad, relatively speaking that is :-), how is it cleaned?. I work around construction equipment/structural my life so this is totally new to me, closest I've been to a boiler is welding the structural decades ago.....Mike
Reply:Ttoks, reminds me of my younger days - 22 years in the power industry.Yep, at one time, I was the guy doing NDT (ultrasonic) survey of boiler tube thickness!One day dropped a hand-held thickness gauge... ting, tang, ting, tang - bouncing off the boiler tubes... all the way down to the ash pit many stories below.  When retrieved, it didn't look too bad on the outside... inside every integrated circuit was broken and the mother board was granulated powder!Thanks for the pictures!Rick V 1 Airco Heliwelder 3A/DDR3 CTC 70/90 amp Stick/Tig Inverters in Parallel1 Lincoln MIG PAK 151 Oxy-Acet
Reply:Nice bro! I hate being bi-polar it's awsomeMy Heroes Have Always Been Cowboys
Reply:ttoks.....good pics.  Notice your tig amperages are quite a bit higher than I'm used to.  Are you running through an amptrol...foot or hand?  Tough to tell from the pics, but are your mouseplates (peanuts) lapped from the outside?  Some of the old ones appear so.   Here we fit them flush and usually weld from both sides.Last edited by OldSparks; 04-12-2014 at 10:24 AM.
Reply:Yeah mate, the mouse plates are lapped on the outside, and welded only on the inside, the amps are high mainly because the tubes being so thick, and being a membrane design are an excellent heat sink, take some power to get it going, and productivity is a concern here, could be done at 130-140 amp's (and some welder's here do), but it would be to slow, here fast welder's that can pass NDT and visuals are what companies look for, i've welded 3.4mm wall, 32 OD B3 economiser tube at 165 if i have a TA to tail off the amp's to prevent worm holes, was able to set up, tack and weld over 120 but's in a 12 hours shift a couple of times.And no amptrol or other remote amp control, welding thin tube when I have a TA helping me i just get him to tail off the amps at the end of the weld, but OHS doesn't allow any HF machines in the boiler (classed as a confined space) and weld procedure's normally spec a fronius 150 caddy, the 2700 synergic i'm using here, or lincoln invertech V350, none have a ramp down function, and we don't use a pedal, because most of the time we're contorted into silly positions and wouldn't be able to use it anyway, there's been times I've  had to hang upside down by my knee's to get to a tube 12 down in a bank.Last edited by ttoks; 04-12-2014 at 11:33 AM.
Reply:No amptrols here but had to ask with that amperage.  Don't think I'd ever get over 120 amps on a 6mm sidewall tube.  That goes to say I wouldn't be anywhere near your production.  Keep up the good work.
Reply:Standard boiler design calls for 10 to 12 square feet of surface area per horsepower. Just to give you an idea how big it is.old Miller spectrum 625 Lincoln SP-135 T, CO2+0.025 wireMiller model 250 and WP-18V torchCraftsman 100amp AC/DC and WP-17V torchCentury 115-004 HF arc stabilizerHome made 4 transformer spot welderHome made alternator welder
Reply:Nice job. Boy that's a lot of scaffolding for sure. You should get flight pay.
Reply:toks; thumbs up for welding in such tight quarters. nice pics.i.u.o.e. # 15queens, ny and sunny fla
Reply:I knew a guy that welded the back side of steam tubes while looking in a mirror.  Don't know if that is normal or not?
Reply:Originally Posted by Fast LeroyI knew a guy that welded the back side of steam tubes while looking in a mirror.  Don't know if that is normal or not?
Reply:Interesting work. BTW, Where is 'here'?"The beauty of the Second Amendment is that it will not be needed until they try to take it." - Thomas Jefferson If the Lights are a Flashin', STAY OFF the tracks!!! It might be me at the Throttle...
Reply:Australia, i won't mention names of the company i'm working for, or which power station though, they like they're privacy.
Reply:So today i ran into a little problem, cracked weld's.Only the short run's are cracking, and they're cracked 12-24 hours after welding, it seem's the welding engineer that designed the procedure didn't take think there was much difference between doing a coupon on 6mm cro-mo plate, while the boiler itself is tied together in every direction, giving it no "give" when the weld's cool, so theweld procedure coupon passed with no problem,w hile on the job isn't, this is the first time we've welded these fins with a Mig, previously they've always been done with Tig, but the company was trying to find a faster way, pre-heat of 200 degree C, but post heat treatment isn't practical due to time constraint's.So.. it's time to do some grinding and repair them, around 30 of the short (4-5 inch) weld's have cracked, so grind the crack out.Throw in a pass with the TIGand a few completed repair'sWelded at 180 amp's on the vertical weld's, 200 on the sloping wall.No water cooled hand piece, so i had to improvise.This section is the only one with no crack's, difference? partly how many weld's in one area, slowing down the cooling rate, and partly running the welder hotter, 26 volt's, and 230 amps, rather then 23-190, and putting more metal in, none of the long run's have cracked at all, the welding engineer isn't sure why this is, but his theory is the longer weld and more heat input slow's the cooling rate of the weld, and the longer run gives more of an area to allow the weld to stretch as it cool's.
Reply:what a job.....I assume your very well paid...$$$$$$
Reply:typical pay is $30hr/100 per diem here in Tx
Reply:Looks sweet man, way different than my day at work...
Reply:Originally Posted by lincweldtypical pay is $30hr/100 per diem here in Tx
Reply:Hey manI just recently got into a job doing the same kind of work. I just got out of school for pipe welding and welding these boiler tubes is WAYYYYY different! any tips on getting into those corners you can share with a newbie??
Reply:Are you team welding the water wall tubes?  One golden arm inside the boiler with another on the outside to pickup the arc.  That's how we used to do it.
Reply:That doesn't look like a lot of fun to do but definitely shows why some welders make the big bucks!
Reply:Originally Posted by Josh HeadleyHey manI just recently got into a job doing the same kind of work. I just got out of school for pipe welding and welding these boiler tubes is WAYYYYY different! any tips on getting into those corners you can share with a newbie??
Reply:This is what I do every day. Fun stuffttoks; a boiler that burns 600 tons of coal per hour boggles the mind. as a much younger welder i worked in many of the powerhouses here in nyc. one of the plants was ravenswood #3 where big allis is located, it was touted as the first million kilowatt boiler. all this was over 40 year's ago so i'm sure this must be small potatoes now. i understand it's now owned by a canadian outfit and burns natural gas but is set up for coal in case of emergency. just to get a better picture of the size of the one in the pics how much bigger is the one you're working on?i.u.o.e. # 15queens, ny and sunny fla