Boiler Element Stud Repair

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
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lee65536
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#1: Post by lee65536 »

Salutations all,

My 99' Brasilia Portofino's element finally gave up the ghost (it was half gone when I purchased the machine), and after 2 days of alternating between heat and penetrating oil I am left with this:



Only one stud really is fit to go back into service. When looking for the replacement element - I've seen 8mm studs (threads on both ends) in the pictorial diagrams. What I find odd is the big chunk of material inside the boiler - is the stud threaded all the way back into that thing? If it is - I don't see much chance of backing out the existing studs and will probably just start drilling. Has anyone "been here, done this"? Looking for advice.

kize
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Joined: 13 years ago

#2: Post by kize »

It is common to have a boiler casting that extends into the boiler for the studs. Creates barrier between the pressure vessel and the stud threads. If it were me- I'd start by heating the boiler around the studs with a torch. Then trying to remove studs while hot. If you break them, you break them. If they don't come out- then it's off to center punch the broken studs. Starting with a small drill bit- drilling at the center, down but not all the way through the stud well. Going to larger bits until you start to see the stud peel out of the stud wall. Then use an easy out to remove the left over stud. WHAT EVER YOU DO- do not break off the easy out in the hole. If all else fails - last resort is to drill, use a bottom tap and helicoil to repair stud well. Take your time. If you don't want to mess with it a machine shop would probably take care of it for you.

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Randy G.
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#3: Post by Randy G. »

This is not the first time this has come up. Here is what you face (or at least how I would approach it): I would use alternating penetrating oil soaking, heating (heat gun or even boiling water), chilling the stud while the boiler is still hot, and using a very small hammer to tap on the ends of the studs- like 100 little taps each, then repeat. The tapping sends vibrations through the studs and is very effective at breaking down corrosion. If that lasts a week, fine. If you can then double nut a stud and get it to wiggle a bit, then keep oiling it and remove in degrees, loosen, oil, tighten, oil, repeat until it comes out.

If a stud will not loosen after that, the best thing is to NOT BREAK IT OFF TRYING! Cut it off and file the end of the stud flush with the surface of the mounting flange (a milling machine is infinitely handy here, but not necessary). Now you have easy access to a flat surface upon which to mark the center, accurately center punch and start drilling.

if one of the studs breaks off below the flange (inside the threaded hole) and is uneven (it assuredly will be) then drilling it straight and true will be exceedingly difficult.
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lee65536 (original poster)
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Joined: 11 years ago

#4: Post by lee65536 (original poster) »

So the metal inside is to seal the "straight" threads on the stud then - that makes sense. I had a coal boiler that had studs that where 5/16 nc on one end and 1/4npt on the other - that way when you threaded the 1/4"npt into the boiler it created a water proof seal. Guess the Europeans have other means........

I've started soaking with penetrating oil (ATF + K1) - looks like I have week till the new element shows up.

thanks
lee

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Paul_Pratt
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#5: Post by Paul_Pratt »

I think you should start to think about removing the boiler, it will make it much easier to do and means you can clean the boiler properly afterwards.

Try and clean up the bottom of the studs so that the oil can try and get down in there. You will need to remove that rust, you can usually get it to break away with the use of a long flat blade screwdriver and a hammer. Also use a wire brush.

After a few days see if the studs will budge by applying heat and then using the double nut method, it is much kinder to the threads. If they don't move with a moderate amount of force then you need to stop before you do real damage and report back here :)

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Eastsideloco
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#6: Post by Eastsideloco »

kize wrote:It is common to have a boiler casting that extends into the boiler for the studs. Creates barrier between the pressure vessel and the stud threads. If it were me- I'd start by heating the boiler around the studs with a torch. Then trying to remove studs while hot. If you break them, you break them. If they don't come out- then it's off to center punch the broken studs. Starting with a small drill bit- drilling at the center, down but not all the way through the stud well. Going to larger bits until you start to see the stud peel out of the stud wall. Then use an easy out to remove the left over stud. WHAT EVER YOU DO- do not break off the easy out in the hole. If all else fails - last resort is to drill, use a bottom tap and helicoil to repair stud well. Take your time. If you don't want to mess with it a machine shop would probably take care of it for you.

Sounds like the right advice.

In December, I was off to a machine shop to ask for help with some a pair of small diameter broken boiler bolts and stopped by my buddy's blacksmith shop on the way. Each nub was about 1/4" long. We were able to remove one broken bolt using heat and vice grips. Since the other still wasn't budging, my buddy spot welded a nut onto the nub. Once we got a wrench on that nut the stud backed right out.

(BTW: I bought a plumbing torch to try the heat technique at home, but that proved useless. This requires substantial heat. Commercial-grade.)

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lee65536 (original poster)
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#7: Post by lee65536 (original poster) »

I tried soaking them all week - I should have not bothered. This morning I removed the boiler and took it to the local transmission shop (my father's) and applied liberal amounts of heat. The top stud came out with out a fight, the bottom left was intense, but at the end of 10 minutes I was down to the last one. Stud number 3, did not budge, after stripping it with the vice grips, I welded a nut fast and busted the stud, nut number 2 held and after considerable work managed to get it all but one thread and then it stripped. So I beat it out with a chisel. One M8-1.25 heli-coil and a total of 2 hours later we are ready to reinstall!

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Eastsideloco
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#8: Post by Eastsideloco »

Right on. Funny how one ornery piece can turn a 10 minute project into a 2-hour ordeal. Hope the rest of the project is easy peasy.

kize
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#9: Post by kize »

When you reassemble- if you put a dab of anti seize on the stud/nut- it might save the next time from headache. Glad the outcome was a positive one.

genovese
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#10: Post by genovese »

You might consider replacing the old bits with stainless steel hardware. I went through similar grief splitting a boiler where a slow and invisible leak over a long period had rusted the original fasteners, and had no desire to repeat that learning experience.

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