Brazing Cast Iron pump body possible?

[farmerbw]

It's about time to start getting my irrigation system put back together and in working order which means I've now got to address a problem I've been putting off since Jan.

Long story short I messed up and didn't fully drain my 1.5 hp well pump before going away for a week, so of course we had a long cold snap AND my "heat" bulb blew. So upon returning I had the pleasure of discovering a "small" crack in the pump body, about 3-4 inches long and wide enough to get a thumb nail into. :BangHead::BangHead:

So my question is it possible to braze/weld the crack externally without having to dismantle the pump? If so does anyone have, or know someone in the Raleigh area that has the means to do it? If required I could dismantle the pump but it's kinda of a pita and my experience with doing it in the past is that I can never recreate the factory seal and always end up with small leaks. :thumbs_do I don't have any pics of it but could get some tomorrow if it would help.

I've never welded but am open to "simple" or cost effective DIY methods that might solve the problem so mods feel free to move to the DIY section if more appropriate.

TIA,
Brian.

 

[Glennbear]

I would fear the applied heat would fry the seals. Having said that, I recently used epoxy to repair a crack in a "pot metal" section of an air compressor. 145lbs. pressure and holding well :icon_thum Modern epoxies have amazing tenacity.:wsmile:

 

[ebrant]

Brazing cast iron is a viable repair process but..... the pump would have to be disasembled because the whole thing would have to be preheated to avoid creating stress buildup and subsequent cracking. I'd try to find a non-heat way of repair. A lot of that depends on how much pressure the repair would see. How about J-B Weld?

 

[jerrye]

+1 on J-B.

It's two part epoxy with metal powder in the resin. Used it to repair may things, and it's never failed me yet. Just make sure your surfaces are dry & clean, & free of any greases/oils. For this I'd use standard set, not the quick-set stuff. It's a bit lower in viscosity, so it might seep into the crack a bit better than the quick-set version. Also make sure you allow it the full 24 hrs before putting pump back into action.

If J-B doesn't completely fix it, it should make it usable. But I think it'll fix it.

HTH!

 

[farmerbw]

Thanks for the replies guys.

I'd actually considered JB weld and thought I was probably reaching real far on it being a viable solution since it would be under pressure. Sounds like it wasn't so far off after all, especially in light of your successful repair Glenn.

This would fairly cheap, which I'm all about :gar-Bi, and worth a try since I could do it with out even fighting to disconnect the input/output pipes. Worst case if I do have to take it apart I at least know the housing could be repaired and not be scrap.

Then again if I have to take it apart I think I still have the old pump that gave up the ghost last year and could use the housing off of it if push came to shove. Guess being a pack rat isn't so bad after all.

Also I recall NAPA or someone carrying a 2 part system that was solid like playdough and after being mixed and hardened supposed could withstand gas, oil, pressure.....etc and also supposedly be tapped to take bolts. Anyone ever see that and know if it's still around? Might be a strong canidate as well. :dontknow:

Thanks again guys for all the suggestions. :icon_thum
Brian.

 

[Mike Davis]

I think the JB weld will hold. But, I would apply it from both inside and outside trying to force it to meet all through the crack. I would take it apart, clean it very well and maybe apply some muriatic acid to etch the metal. If you get it right the first time it should last quite a while. The second try never works for me.

 

[scsmith42]

I concur with the advice offered thus far. If you need to have it welded, send me a PM and I'll be glad to look at it. Three options are oxy-acytelene brazing, TIG with nickle rod, or TIG with furnace brazing rod, the latter probably the better solution.

You will need to fully dismantle the pump, otherwise the seals may be toast (literally!).

JB Weld is an excellent option, and I've also had great success with the SuperMend epoxies. Be sure to thoroughly clean and de-water the pump before applying either one of these, and allow ample time to cure. More time spent mixing the expoxy means a shorter curing time and better end result.

Mike's advice re getting it right the first time is spot on; once you try an epoxy, brazing is probably no longer an option.

 

[pcooper]

Sounds like there are a lot of good experiences here and lots of good advice. My only input here is from an old gentleman that used to run a welding shop many years ago. I was a kid when I knew him and he'd been welding for a LONG time then. He told me that the only real repair for cast iron was gas welding with a nickle rod, he said nothing else would hold up for very long. I guess it would depend on a lot of things, but this old man knew his stuff and made a living welding stuff and making stuff that required a lot of welding.

 

[paul dyar]

Check some of the welding forums. Some on there say you can mig cast. Never seen it done, haven't tried it, but more than one say they have done it.
paul

 

[scsmith42]

I have personally welded cast iron, many many times over the years, using a variety of processes including TIG, Arc, and gas brazing. I've used specialty rods, stainless steel rods, nickle rods, etc.

The challenge is with the expansion and contraction characteristics of CI, as well as it's brittleness. Typically cast iron will crack during or within 60 seconds after welding, because of the contraction of the expanded metal and the fact that it's so brittle.

When you weld cast iron, it becomes heated during the welding process, which expands it. When weld material is added, it then welds the cast iron together in it's "expanded" position, and then as it cools the CI cracks when it contracts.

Nickel rod is preferred because it is a softer material than a standard welding rod, and it will "stretch" a bit as it cools, thus reducing - but not eliminating the potential for the CI to crack.

Brass from a brazing rod is also soft, and will stretch some, also minimizing the cracking potential.

Welding a small amount, and then stress relieving by peening as the CI cools is the primary acceptable method. Even this is not without it's risks though.

TIG is a preferred method because it's heat is concentrated and therefore the CI expands less during welding.

 

[Mike Davis]

Even so, isn't it best to preheat the cast iron, weld it and then return it to the furnace to cool slowly?

 

[scsmith42]

Mike, the answer is "it depends".

Thin cast iron will crack before you can get it back into the oven, unless it's stress relieved during welding. Certain items, such as large engine blocks, are too large to fit into the average available oven.

Depending on where the weld is placed, and any machined surfaces, pre-heating may or may not be a good idea.

In general, it's a good idea. Rather than using an oven, I usually pre-heat by hand with an acytelene torch, and also use the torch to help slow down the cooling process. This also can help the stresses to be dissapated over a larger area.

Some "old timers" would also preheat, weld, post-heat, and then place the CI in a container full of sand to help slow down the cooling.

 

[farmerbw]

Brazing Cast Iron pump body possible? UPDATE w/pics

Well, I finally had an opportunity to disconnect the pump and remove it from it's cramped environment for a closer look and repair. It sort of went down hill quick!! :BangHead::BangHead::BangHead:

Upon getting the pump to the garage and in better light I found that the crack wasn't as short as I had thought and instead runs the entire length of the side of the body, about 12-13". While the crack isn't really "open", I was certain it was "open" at the top when I first found the problem. :dontknow:, there are also a couple of areas that seem to have a splinter off the main crack.

I'm guessing that in order for JB Weld to work I'd need to open up the crack more in order to get the product into it or it would basically have no affect at all?

Scott Smith, do you think that any of the brazing methods you suggested previously would still be feasible?

The crack runs from above the top of the rounded edge to below the bottom of the rounded edge.

You can barely make out where the crack ran here.

and here.

TIA,
Brian.

 

[scsmith42]

Brian, the good news is that the crack did not open up.

If you opt for welding (or brazing, which is what I'd suggest), you will need to totally dismantle the pump and replace all of the seals after welding.

If you opt for JB Weld, no dismantling or new seals required.

If it were me, I would clear away a little bit more of the paint on each side of the crack - say 3/4" or so, wipe it down with a thorough thinner such as lacquer thinner or MEK, and try the JB weld or the SuperMend Epoxy. I would NOT grind out the crack before applying the JB Weld, because if the JBWeld does not take you can "probably" grind it off and then try brazing as Plan B. If you grind out the crack and put JB weld inside it, future brazing is probably not an option.

Give it plenty of time to cure before exposing it to water - at least 24 hours.

Regards,

Scott

 

[farmerbw]

Thanks Scott, that's good news!!! :eusa_danc:eusa_danc:eusa_danc:eusa_danc

I was thinking that if I didn't get the JB Weld down into the crack it would just flake off under pressure. I guess I underrated it's abilities.

Which option do your believe, assuming proper and adequate prep, would have the greatest possibility of success and give the best results? Now that I've disconnected it and have in where it's easier to work on I'm not too pressed about disconnecting the body from the motor, although it's a major pita.

I'm prob leaning towards JB based on the new revelation since it would be quicker and have less down time, just concerned about options if it fails. I need to get a better wire wheel for my drill to aid in getting it cleaned up more though. If push comes to shove I've actually got another pump body that's identical and I just removed the studs from it yesterday in case the plan changed to just a straight tear down and assemble with the other body.

Thanks,
Brian.

 

[scsmith42]

Thanks Scott, that's good news!!! :eusa_danc:eusa_danc:eusa_danc:eusa_danc

Which option do your believe, assuming proper and adequate prep, would have the greatest possibility of success and give the best results?

Brian.

Brian, either one should work acceptably well. Proper preparation is the key for success. For the JB Weld or Supermend Epoxy, I cannot stress enough how important it is to thoroughly degrease the surface as your final step. I typically use a propane torch to lightly heat the surface after the final cleaning, as that removes any residual cleaner that's left in the pores. It doe not need to be heated much, just enough to evaporate whatever's in the pores. You can actually see the moisture coming out as you're heating it.

I would stive for an expoxy bead that was around 3/4" wide, and around 1/8" - 3/16" tall, feathered to the edges.

If I were doing it for myself, I would probably go the brazing route but then again I have a lot of $ invested in welding equipment so the opportunity to use it always helps to psycologically justify the initial investment! ("why yes dear of course we needed that expensive welder - see how we've used it to repair this pump?") :gar-Bi

 

[DaveD]

I'm not a fan of JB Weld. Since you already have the other pump body disassembled why not expend a little more effort and swap bodies? That way you know the fix should be a quality one.

I'd go the brazing route before JB Weld but would preheat the casting either in the grill or the oven to help eliminate thermal shock of the brazing torch on the casting. Then I'd bury the brazed casting in sand to slowly cool it overnight.

Once you got it fixed I'd recommend you wrap it with heat tape to prevent future freezing problems.

If thet pump housing is cracked all the way around, don't be surprised if it literally falls apart at the slightest bump while you are trying to fix it. thew impeller and shaft may be the only real thing holding it together.