Pressure proof welding

[tuolumne]

Welding fittings on my propane tanks for heat storage has proven an exercise in frustration. I have a 110V wire feed welder with argon that probably lacks the gumption for this job. I used weldolets and everything was cleaned to bright white metal. What I have is some nearly microscopic cracks on each of the welds where pressure escapes. I have ground out those areas and rewelded to find the pressure finds a new outlet somewhere around the patch. Help!

My thought would be to apply some appropriate epoxy around the inside of the fitting/tank interface. Will this work? Structurally, the epoxy only needs to bridge that microscopic crack. If this will work, what is an appropriate epoxy for 200 degree water application. I do not think that welding will solve this unless I can find a 60' extension cord for the stick welder at work. Even so, my forarms were sunburned and I do not want to weld any more. I also do not want to buy any more grinding wheels at this time! Advice please...

 

[Adios Pantalones]

Hire a pro. Seriously- I own a welding machine but will hire someone when it's time for a pressure vessel.

 

[Dune]

DON'T HAVWE MUCH TIME, BUT HERE GOES, aRGON WILL NEVER WORK FOR THIS TASK. You need staight CO2, like from a soda bar. 11o mig is pushing it, but is doable, with 3 passes. Preheat the fitting and the area around the fitting to about 300- 400F. Argon will not work, period.Welld entirely around from one starting point, start the next pass 180 degrees from there, repeat.

 

[taxidermist]

I had the same problem but mine was from cheep china cast couplings I keep grinding and welding till no more bubbles. If I had to do it again it would get black pipe nipples and no cast fittings.

Rob

 

[maurice]

tuolumme - Lots of welding tips on MachineBuilders.net, covering this very problem.

And in this thread: http://www.machinebuilders.net/forum/forum_posts.asp?TID=4463&PN=1 we have a doctor-member who advised us that he has removed skin cancer from welders. Please, cover your skin when welding!

 

[Northwoodsman]

I just completed the installation on my EKO40 system with (2) 500 gallon propane tanks stacked on top of each other (and joined at the middle with 3 different 1-1/4" lines//unions/ball valves) horizontally and thus had to weld many fittings on each tank.

I did not use cast iron fittings because of the issue with pourus castings. Rather, I used all steel fittings.

I used a Hobart 240V welder with 75/25 argon/CO2 mix gas and had 2 welds that I had to go back and "patch". The problem for this is that I actually had my 2 tanks stacked and in position when I cut the holes in them and installed the fittings (so that I could keep proper alighnment) and thus it was difficult to get in a good position for welding.

I used a torch to cut the openings and made sure that the area's to be welded were ground clean before welding. I also tried to cut the openings 1/8-1/4" larger than my fittings to make sure I rec'd full penetration.

I have been using my system now for over 2 months and have had no leaks !

Hope this helps !

 

[tuolumne]

The welder was borrowed from my neighbor. He also has a 110 flux core. Would that be better than the MIG for this application? If I am pre-heating with a MAPP torch can I possibly get things too hot? Do I need to clean again after torching? I'll definately wear long sleeves next time! No takers on the epoxy, eh?

 

[taxidermist]

The welder was borrowed from my neighbor. He also has a 110 flux core. Would that be better than the MIG for this application? If I am pre-heating with a MAPP torch can I possibly get things too hot? Do I need to clean again after torching? I'll definately wear long sleeves next time! No takers on the epoxy, eh?

No use the one with sheilding gas. Use the welder turned all the way up and go slow pushing the weld not pulling it. Are your fittings cast or steel? if you have to stop welding make sure you over lap your stop and start points.

 

[coolidge]

Try spot welding your way around it. The little wirefeeder your using isnt designed for continous use(running a bead), You will need three passes to get the best results or use a stick welder. We use the spot welding idea on some of the Navy ships we built.

 

[steam man]

This is killing me-get someone with a stick welder with some power for penetration, possibly a gas driven one and can weld halfway decent. It will be worth it to save your arms. There's nothing about the steel that requires a special gas or preheating. Just need some oomph and experience for a pressure vessel.

Mike

 

[Dune]

This is killing me-get someone with a stick welder with some power for penetration, possibly a gas driven one and can weld halfway decent. It will be worth it to save your arms. There's nothing about the steel that requires a special gas or preheating. Just need some oomph and experience for a pressure vessel.

Mike

Sorry mike, but this is just plain wrong. Yes a bigger welder would be easier, but this weld can be done with a 110 mig. Pure Argon gives no penetration, pure CO2 gives excess penetration. This helps to make up for the lower power. Next, preheating enables the 110 mig to develop enough penetration, by preventing the mass of the steel tank from conducting the welding input heat away. Finaly, a mapp torch is not nearly enough heat input for this job, and weldulets and couplulets are not cast iron, they are especialy made to be welded.

 

[steam man]

This is killing me-get someone with a stick welder with some power for penetration, possibly a gas driven one and can weld halfway decent. It will be worth it to save your arms. There's nothing about the steel that requires a special gas or preheating. Just need some oomph and experience for a pressure vessel.

Mike

Sorry mike, but this is just plain wrong. Yes a bigger welder would be easier, but this weld can be done with a 110 mig. Pure Argon gives no penetration, pure CO2 gives excess penetration. This helps to make up for the lower power. Next, preheating enables the 110 mig to develop enough penetration, by preventing the mass of the steel tank from conducting the welding input heat away. Finaly, a mapp torch is not nearly enough heat input for this job, and weldulets and couplulets are not cast iron, they are especialy made to be welded.

Plain wrong? And you say: quote-"Yes a bigger welder would be easier"?? We're talking about someone who looks like they don't have the experience for pressure vessel welding. I am not sure why suggesting stick welding sounds wrong. My experience in shipyard welding plates shows that stick welding results in less cracks than mig. I've welded many high pressure lines with a stick. Though CO2 gives better penetration and is generally used more because it is cheaper than argon or argon/CO2 mixes, I am not convinced it makes much difference to an inexperienced MIG welder. Check out (broken link removed to http://www.lincolnelectric.com/knowledge/articles/content/migfaq.asp) I think a good standard 6010, 6011, or 7018 rod is much less forgiving. And no preheating. A gas welder just eliminates a really long extension cord. I never said it couldn't be done with a 110V mig welder, I could probably do it just fine with some patience. If a bigger mig welder is available and power for it, go for it. I just don't think a pressure vessel is something to practice welding techniques on.

Mike

I just checked out Lincoln Electrics 110v MIG welder. They only rated it up to 10 gauge sheet steel for gas welding and up to 5/16" for flux core welding. A propane tank is probably 1/4".

 

[tuolumne]

The gasoline stick welder would need to wait until spring to access our basement with a steep yard and lots of snow. I think my neighbor has 50' cords and that isn't quite enough from the driveway. He is an experianced welder, but is laid up with caral tunnel surgery for a few more weeks. I would probably be better off waiting for him to recover. I only have a few pin holes, so I will still try to spot weld them with preheat. I think that will make a big difference with this welder; I noticed that with the tanks full of water I got very little penetration (explosion protection) and when I drained a bit off I did better. That water was sucking away too much of the heat. Also, I can't build a weld like with a stick welder since the puddle cools off too fast. That leaves moving very slow as the only option. Thanks for many good tips. I'm ready for another go.

 

[steam man]

In my edited post I noted Lincoln rates the flux core wire feed much higher in penetration. Get the neighbors flux core machine you mentioned. Next, now realizing the tank is full of water I know that will cause you a big problem. In my profession, welding below the water line inside a ships hull is not allowed because it cools off of the weld much too quickly and causes cracking. You should try and gas freeing the tank another way. Hope I didn't sound like I was trying to insult you. If I were closer I would weld it for you.

Mike

BTW- I have burnt my arms and neck many times.

 

[tuolumne]

The water line is currently below any of the weld points by a few inches. The tanks are undoubtably gas free, having been cleaned and filled. All of my grinding, welding and torching would have surely gone kaboom by now.

 

[taxidermist]

OH YEAH if you had the water next to the weldoutlets(sp?) and you were pre heating and welding you might be making steam that will push thru your welds also cooling your welds I too went and looked at the flux core wire and you will get better heat from that.

 

[Dune]

There's nothing about the steel that requires a special gas or preheating.

Mike

Pure argon (read the original post, he said argon, not argon-co2) gives NO penetration, leading to micro-cracking upon cooling. The fact that he is getting otherwise good welds, except for the micro-cracking is why I posted the info that pure CO2 and proper pre-heating will enable him to make pressure tight welds even with a 110 unit. CO2 is not a "special gas", just the only gas that will work in this situation. Pre-heating is always called for, when asking a small machine to do a large task. It goes without saying that a pro with a stickwelder could do the job faster.

 

[tuolumne]

I hardwired a 240v stick welder into an electrical panel 40' away and fixed the fittings....good penetration, no leaks at 60 psi. I've filled the system and run on storage for a few days. With minimal insulation, I've only heated the tanks to 140 and the basement is still uncomfortably hot.

The problem:
After knocking the slag off the welds and shining things up for spray foam insulation, there is a slight water seepage from one of the welds. It is quite slow but has not stopped since Saturday. The welder is disconnected and gone. Are any of the "leak stop" type chemicals effective? Do they harm parts of the boiler sytem? How much would I need for the volume of water involved (1200 gallons)? The leak is not significant enough to affect the system, but may cause mold etc. under the tanks once everything is foamed in. Thanks, Chad.

 

[Ugly]

That'll make an awful big puddle in the middle of January if it's not well done. I have a light lincoln gas mig (20 amp) and can honestly say I never thought of using it for that type of application. It's great for light trailer type jobs but you really have to work one perfectly to get any serious penetration on thicker metals even mixing gases. I admit I just turn on the Miller select AC or DC per application (and rod) and sleep peacefully. Just what I've experienced. Admittedly, some people are miracle workers with any tool, I'm the type who gets a bigger hammer.

I didn't like the epoxy idea , though I did fix a hole in a steel pressure pipe with the stuff you mix together by kneeding it. Product was rated off the charts, seems to be holding, but truly I'm jumping up and down for warmer weather so I can replace that pipe section.

Small leaks will sometimes rust closed

 

[Singed Eyebrows]

Get some wicking Locktite(the green stuff). This will go into very fine imperfections & set up permanently. When GM had differential casting pinholes many years ago they painted the inside of the pumpkin with Locktite, end of problem, forgetaboutit. Good luck, Randy

 

[jebatty]

Also could consider J-B Weld. They make many different varieties. A good friend of mine with an old, pressurized boiler that developed leaks, used it to seal the leaks and it worked well. He is in the process of buying a new gasification boiler.

BTW, I'm about to try my own weld fittings on my 1000 gal lp tank. I've got a Lincoln MIG 215. Where did you place your inlets and outlets? Are you achieving good stratification in each tank? My 1000 gal is installed horizontal (39" D), and with "still" water I get about 20* stratification, but with charging or drawing I see lots of mixing taking place.

 

[Hansson]

this is a nice weld on the orlan "EKO"boiler.
I wonder if its Pressure proof :bug:

 

[johnn]

Better late than never! Hoprfully someone may still benefit from this reply to your problem. "ARGON' would have been great if you were TIG welding (aluminum), however for mild steel you would need as mentioned in thread (#5)) a 75% Argon, 25% carbon dioxide mix. Gas shield welding. is best suited in a controlled enviroment! (period) The slighest breeze, one you didn`t even feel can effect your effectiveness of the shield. In the field you would need to turn your regulator way up, even then unexperienced welder`s may pull the nozzel unadvertantly to far from the puddle, losing their shield. Flux core wires provide the shield effect, however they contain solid slag`s which once again will have undesired effect if you are not able to stay in the puddle.Maintaining the angle of your wire gun to the puddle, plays a big role in the sucess of either welding procedures. To weld 360 around a small radius such as a threadlette, and maintain your gun angle to the puddle, particularly, in the field can be quite challenging. Set up, and do a dry run to see how far you can controlling the gun and angle,,then weld only that much! Grind the beginning and end of each weld, to a taper, then tie-in and continue again. Strive for at l;east 180, and complete in two passes. Generally speaking, these fitting have generous bevel`s, and once mostly filled in with welds,,,do not require, beveling the cut out hole,,or enlarging the hole,, in order to gain penetration.

Just as noteworthy: Once slag pit`s (porosity) has developed with wire welding, unless experienced with this,,, your Done. Your eyes simply wont see all the porosity in the weld, or that just under the surface which the next weld will penetrate, and bring to the surface. Short of having,,SKD by MAGNAFLUX SPOT CHECK, you wont find it all. This is a 2-part die and developer, Which the water soluable die is sprayed on, then wiped off with water and rag,,next a talcum powder aerosol is applied and quickly dries, leaving a white background and wherever porosity or cracks exist,,there will be a pink spot or line,,,these will then be ground and resprayed untill no more pink exists. It has the ability to detect sub surface inperfections,,the pink just wont be as strong in color.

THE thermal transfer associated with the water and by using the wrong gas,,,resulted in cracks. The fittings held heat longer while the tank and water were extracting heat... with that gas, the weld wont hold up to the thermal stress.

NOT to say,, you cant weld on a supply tank almost full of fluid...Heck you can weld a patch on a DIESAL tank, below the water line, as long as you remove one part of the equation needed for combustion. With the tank mostly full you simply drop "dry ice" into the tank which effectively removes the oxygen, after closing the lid,,weld away..A Marine Chemist would monitor oxygen supply before issuing a permit, and should be contacted to determine the amount of ice needed for a particular size tank.

A 6010 root pass,,6011 filler passes,,and 7018 cap may have served you better, but you still need some experience. Most farm boy`s would have simply used the 6011 only, and had success. The three rods mentioned earlier, would be the process in order to certify for pipe welding.

 

[kenny chaos]

Most farm boy`s would have simply used the 6011 only, and had success. The three rods mentioned earlier, would be the process in order to certify for pipe welding.

Now your talking some common sense. Guys never get good mig welds, just mig welds that look good.
It sounds like some exceptions out there so don't be offended.

Weld on!

 

[topofthehil]

I was taking down notes all of the way through the thread for what was mentioned and not mentioned about shielding gasses and filler metal.
burning chunk covered most of the do and don't very well.
also, was there mention if this was a section 8 pressure vessel, or is it an open system?
I would not use the self shielding flux core with a 110 volt welder for this type of work.
I would not use the 110 with solid wire and 75 Ar/25 CO2 or 100% CO2 shielding gas either.
it may look good, but you will not get enough penetration.
also, I doubt if someone with a 110 volt welder uses 100 % Ar gas.
more than likely they had a 75/25 mix with solid wire.
hopefully they did not use gas with a self shielding flux core.
putting gas on a self shielding flux core wire makes it look good, but you will get delayed cracking sooner or later.
maybe this is what happened?