Eutectic - Cavitec

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Good afternoon folks!One of our large hydro electric generating stations is currently getting a full runner (turbine blade) replacement to improve efficiency. As you know these units acquire cavitation pitting which require us to go in and gouge out the bad material, fill, and grind. Generally our procedure for the old units is fill all the way out with 309. But with these new blades our procedure is fill 309, and then apply a capping pass with cavitec then grind. This is our first unit running the cavitec and it burnt alright for a hard facing wire, it was slow going compared to 309 but nonetheless we got this 2 units finished. We did experience feeding issues with our older L-tec 35 wire feeders, its a very brittle wire, and does require knurled rollers for feeding. We run Binzel M 105B water cooled guns. IF any of you out there are doing the same kind of work what are you using for wire feeders? We are looking into upgrading/replacing our current l-tec cavitation machines with 2 lincoln invertec 350 pros, and 2 ironworker    L25 wire feeders. The l-tec power sources run great, but after 30 years of cavitation welding theyve paid their dues. I am a boiler maintainece welder at our coal fired generating station, but I used to work at this hydro electric plant years ago and was asked to start assisting on these units with cavitation as the new guys have no experience. Added some pictures for those who havent seen it before! We use Ltec plasma gougers, setup with air and hydrostar hydrogen gas to superheat the arc, setup to gouge 80lbs of material an hour. This particular unit wasnt that horrible, all liner work mostly, although some of the cavitation got as deep as 3/4". Not too impressive for a brand new unit that only has about 30,000 hrs on it. it will be interesting to see how well this cavitec works, at 1600$ for a spool it had better! Attached Images
Reply:Pressure Welder  -  Reminds me of the 'bad old days'.  Good pics and good information, big stuff is a learning lab that everyone should try. To be effective you have to be comfortable, what is your hood andrespirator set-up?  Please post more when you can.   Opus
Reply:Once this cavitation is discovered in an area, then you do your thing for those spots, what's to prevent it from happening to the left and right of the small spots you've done? Is there some change that can be made while it's all apart to solve the whole issue? What's causing the cavitation to be be gin with? Rough spots, smooth spots, high spots, low spots? "The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:nothing is really setup to "prevent" cavitation per say, its just a nessecary evil of running hydro electric turbines. Cavitation is literally exploding water pockets/bubbles that erodes the metal away. Its usually created by a low pressure area from the turbulance from the runner. Essentially when you start getting a decent "pocket" of cavitation it just grows more rapidly as it disturbs the clean water flow over the countoured parts. Thats a main reason for this cavitec wire id imagine, its supposed to prevent any premature re-occurance of cavitation in that particular area. -opus,its not really an issue of not knowing how to weld the wire, iam simply interested if anyone is running it in a similar situation and what they are using to feed it with. It is a delicate wire, and unforunately our 25-30 yr old wire feeders are slightly "barbaric" to put it bluntly to feed this wire properly i am thinking. As for my fresh air helmet its the new speedglas 9100xx FX, with adflo. I try to use it whenever i can, hard to tell but the smoke gets pretty thick down there with two of us welding/gouging at the same time, even with the generating station pressurized.added another picture of my trainees welding helmet. First thing i tell any apprentice who picks up the gouger, keep your face as far back as possible! and hands under the torch shroud! Added a couple other pictures of a brand new plant that is being built as we speak, i had a few jobs to go and do there a while back Attached Images
Reply:few more, inside the scroll case at the new plant being built, me stand in intake 3, picture of the distribution ring, stay vanes, and wicket gates being held close by cables for now. Attached Images
Reply:Thanks for posting this P_W.What a neat job you have.Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:Can you gives a hint of where this worksite is? Also how many megawatt is the turbine able to produce?
Reply:Im not a huge fan of the invertecs i would say XMT350's and LN-25'sVantage 500's LN-25's, VI-400's, cobramatics, Miller migs, synch 350 LX, Powcon inverters, XMT's, 250 Ton Acurrpress 12' brake, 1/4" 10' Atlantic shear,Koikie plasma table W/ esab plasmas. marvel & hyd-mech saws, pirrana & metal muncher punches.
Reply:Those pics are great. I would suggest a 4 roll feeder based on the issues you are having,  I think there is a 4 roll version of the LN 25,  My ESAB 300AVS is a standard 4 roll feeder...   that way you are distributing the feeding force across twice as much wire area...  one roll is doing the pulling off the spool the other is doing the pushing into the gun...Tiger Sales:  AHP Distributor    www.tigersalesco.comAHP200x; AHP 160ST; MM350P,  Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma.  For Sale:  Cobra Mig 250 w/ Push-pull gun.  Lincoln Wirematic 250
Reply:i believe each unit is capable of around 70-80 megawatts. Definatly not as big as some of our other plants, but certainly good for a station with only 3 units and not a very large head. This plant is in northern manitoba. Ive used the invertec's quite alot and they seem fairly rugged especially on the applications ive put them through. Not to sound bias but i wouldnt run a miller machine in our shops, especially down at my coal fired station, especially when it comes to tig roots in our boiler i find nothing beats a lincoln, even the boiler makers that come in to do very large jobs that we cant handle on our own only use lincoln. We had two millers on site that just couldnt produce what we wanted so they were sent back and lincolns purchased.I agree southpaw, moving to a 4 roller unit would be much preferable i believe. Less stress on that one roller to pull and push at the same time.
Reply:Cool stuff, thanks for sharing! Be safe bud!  I hate being bi-polar it's awsomeMy Heroes Have Always Been Cowboys
Reply:Interesting that you  find the Lincolns work better for you..  seems to be a lot more Miller fans around here, except when you get to engine driven stuff like the SA units...Tiger Sales:  AHP Distributor    www.tigersalesco.comAHP200x; AHP 160ST; MM350P,  Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma.  For Sale:  Cobra Mig 250 w/ Push-pull gun.  Lincoln Wirematic 250
Reply:I suppose ive just used lincolns for so many years its hard to change over. On the boiler side just about all ive seen is lincoln. We have two lincoln 600 ampers on carts, one bank of 4 invertecs for the superheater section, and then in the shop i have a precision tig 275, and the other pressure welder that i work with has a syncrowave 250DX which he dosent mind for stick but when hes running tig roots in the shop hell roll in one of our lincoln machines from the plant. We've just had so many trouble free year with lincoln itd be hard to switch.
Reply:nice post as always PW...  now, when can i pack my things and come apprentice?
Reply:thanks martini, i always enjoy looking at other interesting jobs from other guys, so i figured id throw these pictures in!
Reply:PW:  you've gotten me motivated to start taking pics at work so i have been, i should start a thread.   As you know, where i work we build all the types of stuff that you do maintenance on, so pics of drums and panels might be kind of boring   PS. Check your PMsLast edited by Martini; 07-23-2012 at 06:41 PM.
Reply:would love to see some pictures of steam drums and panels! do you guys make condensers also? Have a loop pipe job coming up on the turbine, origional piping has acquired creep so shes no good! 2 1/4" thick wall, 8" diameter 2 1/4% chromo
Reply:There's something kinda freaky about those pictures, crazy stuff for sure.Welding/Fab Pics: www.UtahWeld.com
Reply:Pressure Welder  -  Your last photos are emblematicof a High Priest in the temple of Karnak.    Opus"Welders are Gods"    D.B.  -  Nevada, US. 1980.Last edited by OPUS FERRO; 07-24-2012 at 02:53 AM.Reason: Canucks don't get their due.
Reply:We use an epoxy product called Blue Seal to repair cavitation damage in the nozzles around the propellers on our tug boats.  In the past I have seen stainless steel wear liners welded into the nozzles but current trends seem to have moved away from stainless liners and towards an epoxy repair at about the midlife of the nozzle.Here is a link to a repair example  http://khia.belzona.com/app_know_how.../xxii_no_3.pdfLast edited by 76GMC1500; 07-24-2012 at 03:07 AM.
Reply:76GMC,Hope all is well, unfortunately the life expectancy of these units are 50 - 60 years of running so going to an epoxy repair wouldnt be very practical, especially with the incredible amount of turbulance. The headcovers are cast steel which cant be welded so we use a product called devcon steel putty to repair any cavitation on there, it seems to work well, but even that erodes and needs more added each time we go in to do cavitation.
Reply:Looks very interesting, I would love to work on work on those things!