welding a 6" bore hydraulic cylinder tube

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I am building large hydraulic cylinder tubes. I am using a millermatic 252 with flux core .45 wire and an external shielding gas. The top of the tube is threaded into the rest of the tube and has a large v groove to weld. My first attempt at this I used two welds on top of eachother, but my top weld had a few pits in it when it was machined down closer to size. Any tips on getting it to clean up better? Different wire maybe? This is the first time welding something of this size that had to cleanup up completely when machined so its all fairly new to me. Thanks.
Reply:Originally Posted by duffjohnI am building large hydraulic cylinder tubes. I am using a millermatic 252 with flux core .45 wire and an external shielding gas. The top of the tube is threaded into the rest of the tube and has a large v groove to weld. My first attempt at this I used two welds on top of eachother, but my top weld had a few pits in it when it was machined down closer to size. Any tips on getting it to clean up better? Different wire maybe? This is the first time welding something of this size that had to cleanup up completely when machined so its all fairly new to me. Thanks.
Reply:If I was doing it I would clean the snot out of everything and weld with 045 hard wire, no slag after welding.
Reply:How old is your wire? I had similar troubles with stainless dual shield. The problem cleared with a new wire from sealed container. Figured moist wire. Have never gone wrong with hard wire in a shop enviroment. Also soak/clean with acetone or a very very very hot presure washer helps wonders.. Pictures?TOOLS AND TOYSSMAW Mid States Inc. "MISSING LINK" 10-150 AMP Buzzer circa 1945ishSMAW Magic Wand 40-60 AMP Suitcase Buzzer circa 1939ishGMAW Hobart 210 IronmanOxy-Propane TorchMany other old and cold goodies"Rusty but Trusty"
Reply:i'm not really a wire guy buy any strectch, but what type of material/tubing are you using, and is it all new/un used?     if not where/what/what oil,  was it used for?    decribe
Reply:I am building these from new honed 4140 tubing. I believe the top piece is the same, and i made sure to clean the heck out of it. The wire is maybe 6 months old, i may have to try solid wire though. Also curious if it is just too big of a gap to fill in using wirefeed. Might have to go with more then 2 or 3 passes.
Reply:I thought those were typically done root 6010 and 7018 cap. Or TIG root and 7018 cap. There may be other methods but I dont think they involve FCAW with gas  But then Im your typical above average backyard weldor. If I may say so
Reply:I would prefer arc welding, but all i have at the shop is mig, anyone recommend using flux core or solid wire on 4140?
Reply:Originally Posted by duffjohnI would prefer arc welding, but all i have at the shop is mig, anyone recommend using flux core or solid wire on 4140?
Reply:I guess i should of included the fact that these cylinders are a ram type, the top that i weld onto the main part of the tube will be the top part of the ram, which has another cap that sits on top of it when all said and done. After doing more research on welding 4140 i will be preheating much more and post heating, plus wrapping in a welding blanket to slow the cooling. Any thoughts on using er80 type for wire?
Reply:Having weld-repaired hydraulic cylinders in the past, I concur with the following:1) Clean, degrease, clean again! Hi pressure oil has worked it's way into every imperfection of the steel.2) Solid core wire. And plenty of gas.3) Make sure you set your welder 'hot' enough for good penetration. Your customer will be dealing with 3,000+ PSI of oil!Be wary of The Numbers: Figures don't lie,. but liars can figure.Welders:2008 Lincoln 140 GMAW&FCAW2012 HF 165 'toy' GTAW&SMAW1970's Cobbled together O/A
Reply:looks like solid wire is it! thanks guys
Reply:Originally Posted by duffjohnI would prefer arc welding, but all i have at the shop is mig,
Reply:Ok you got me there, meant stick i guess. Ive always used stick on larger applications like this.
Reply:So your working on the cylinder rod, not the tube, correct? The rod being the part going in and out to move the load. I have never heard of one being a "tube", as they have all been solid all the way through. The tube(cylinder) would be where the piston resides, and the rod goes in and out of.Your building up the O.D. of the rod, not the I.D. of the cylinder, right?
Reply:Telescopic dump hoist cylinder? Seems to me the old Euclid scrapers used tubular cylinder rams too.
Reply:The inner rod on this type of cylinder bolts to the bottom of a large housing, the top of the tube acts as a ram, its basically a very large floor jack.
Reply:Why are you welding a threaded connection? There is going to be stress in the joint.Mike
Reply:Ditch the flux core and switch to 0.045 solid wire with co2/ar.  AWS CWI xxxx21711968 SA200  Originally Posted by WelderMike  I hate being bipolar, It's awesome.
Reply:Yes the top of the cylinder/ram threads into the the rest of the tube, the picture of threaded part is earlier in this post. The way it sounds is for what I have to work with, the setup will be solid .045 wire, ar/co2 for gas, preheat with a torch, multiple passes, small amount of post heat with a torch, and wrap in a welding blanket to slow cool. Going to grab some scrap 4140 tubing that we have and cut some larch grooves into to practice with first, wouldn't want to waste any more of the prehoned tubing we have. Thanks for all the imput guys, i will let you know how it turns out.
Reply:oh and leightrepairs, we thread the top and weld for extra safety since there will be around 10,000psi in the cylinder.
Reply:Originally Posted by duffjohnYes the top of the cylinder/ram threads into the the rest of the tube, the picture of threaded part is earlier in this post. The way it sounds is for what I have to work with, the setup will be solid .045 wire, ar/co2 for gas, preheat with a torch, multiple passes, small amount of post heat with a torch, and wrap in a welding blanket to slow cool. Going to grab some scrap 4140 tubing that we have and cut some larch grooves into to practice with first, wouldn't want to waste any more of the prehoned tubing we have. Thanks for all the imput guys, i will let you know how it turns out.
Reply:Originally Posted by AFFENDEDitch the flux core and switch to 0.045 solid wire with co2/ar.
Reply:I used to do this prose for atlas hydraulics in Clearwater fl. we used dual shield flux core wire in 045. dirty terrible wire with a lot of slag. 3500 psi cyl in rapid use on automated garbage trucks. constant banging deadheading.reg hard wire likely wont have the strength to hold them.
Reply:Dual-Shield should work but you need to find out what's causing internal porosity. Wrong machine settings, shielding gas problem, etc.to fast  maybe  or to hot,,, more puddle time to let poop get out
Reply:Not sure of the dimensions of the parts involved, but judging from the piece you are holding in the one picture I doubt the end cap is thick enough for a cylinder operating at 10,000 psi. i believe any of hte weld processes listed n this post will work, as long as they are done correctly. I would recommend resolving the issues you are having on some scrap. Please be aware of the damage that oil at 10,000 psi spraying out of a pin hole can do, if you need information on this pm me and i will send to you.Mike
Reply:Originally Posted by HT2-4956That's a respectable size cylinder.   I'm curious as to how you're rolling that.   Do you have a helper manually turning it for you?
Reply:Thanks for all the input guys, sorry it took me so long to get back to the post, i was on vacation for just under 2 weeks. Using a 75/25 argon/co2 mix right now. Definitely going to get some scrap pieces to practice on for a while, these cylinders have been made for almost 20 years now, we have some "issues" with the shop that was making them for us before now, so I am not too excited to ask them how their setup for welding them was, even if they would tell me which they would most likely tell me to shove it haha, but the print has been the same for over 10 years now. If i cant get the flux core and this mixture of gas to work for me, i will switch to solid and try that. I still might try to get ahold of another company that use to make them as well.
Reply:Is it doing this all around or just the last few inches?
Reply:its doing it a small amount most of the way around. I'm thinking it has to be something to do with the wire. Maybe its sat around too long since its a large spool and has some moisture on it? It seems to be welding to the material just fine, its just in the puddle itself where it is getting porous.
Reply:duff,Most codes usually allow for a certain amount of small porosity to be present in a weld.   Admittedly it's not very much but the appearance of the occasional small diameter pore (.030 or less) isn't cause for to much worry.   Making the call on how much is too much is based on the diameter of the porosity and how many of them there are per linear inch of weld.Have you tried grinding out one of these exposed porosity spots to see if there's a bunch more of it down deeper in the weld metal around it?  Since you say your spool of wire has been sitting around for a while I think the first thing you ought to do is get a brand new spool of it and give it a try.
Reply:We cut into the weld a bit deeper and its porous as well. it needs to clean up a bit better then it is because these will be chromed after machining. I will add a few more photos to show a bit more of what the cylinder/ram is like.
Reply:its a 3/4" wide gap that will be welded all the way around. an additional load cap will sit on top of the cylinder as well for protection to the top of it. So the load sits on that top threaded piece i am welding to the tube.Last edited by duffjohn; 05-25-2016 at 09:48 AM.
Reply:Just a few other things to consider that you likely know. I believe there are two main categories to dual-shield wires. One of them being an all position electrode, and the other being for flat and horizontal. The one that is considered an all position electrode, while it is categorized as all position, is generally a fast-freeze wire. Using it in the flat or horizontal position can actually trap slag since it is "fast freeze".  I would suggest using a wire spec'd for flat or horizontal if you wish to use dual-shield and IF you are planning on welding it in the position shown. I have repaired a number of cylinders that have cracked on the welded end. Upon grinding out the old weld, I have numerous times been suprised at the amount of trapped slag in the factory weld. Eventually with enough of shock and fatigue, the cylinder will start to leak.They can crack with enough shock and fatigue anyway, but seem to fail sooner with slag trapped in the weld. With the way you have it machined, I believe solid wire would work very well also. Good luck!! The machine work looks good from here also.
Reply:Thanks for the input on the dual-shield wire types. I slightly remember something about that in college but has definitely slipped my mind since. I will be welding these on two roller stands and rolling them by hand unfortunately, so I will be running the gun with one hand until I can come up with some type of motorized turning device without spending too much money. And thats what a 300k haas lathe will do for you haha.
Reply:duff,Good looking part.  That weld prep should certainly work well.  I like it.   When it comes to roll'n....while a set of motorized tuning rolls would be best there's no reason it can't be done manually using some decent rigid casters.   I'd set up so I was welding standing up at about belt buckle high.   I probably also get a jack stand involved to rest the fore arm of my gun hand in / on.   Also try and get the gun conduit supported so as little of the weight of it is on your gun hand.The trouble with just tacking some casters to the bench top is that it ends up to high off the floor for a comfortable welding height.   Don't know how many of these you've got to do but it might be worth while to make up a set of saw horses you could tack your casters to so that things ended up at a good height for welding.  Plus when the jobs over you can cut the casters back off them and just use them for other things.
Reply:the casters were my first idea, but then ended up finding these roller stands for fairly cheap on a website. We have some scrap 4140 that i can cut some grooves into and practice on so i think i will pick up some solid wire and get started again. I appreciate all of the info.
Reply:Originally Posted by duffjohnthe casters were my first idea, but then ended up finding these roller stands for fairly cheap on a website. We have some scrap 4140 that i can cut some grooves into and practice on so i think i will pick up some solid wire and get started again. I appreciate all of the info.
Reply:The first cylinder i put on the stands was very stable, but i will be doing even bigger cylinders soon so i might need to stabilize it more when the times comes. The first cylinder I clamped the ground on the back end of it and that seemed to work great. wasn't in my way and didn't make it harder to roll the cylinder.  I have decided to give solid wire a try because I talked to the welding supervisor at the shop that did the larger cylinders for us and he said they have always used LA-100s. So I figured if its worked great for them, it wouldn't hurt to give it a try. But if i have problems with that i do still have a brand new roll of the flux core i was using before. He mainly suggested this wire because of the high tensile strength.