The Home Machinist!

i lit my first fire in the Sweet William today and found a steam leak. it's on the dome where the top plate meets the vertical tube forming the dome. it's a tiny pin hole leak but needs to be fixed. my first thought was to soft solder it to seal it.

any other ideas would be appreciated.

_________________
Fred V
Pensacola, Fl.
home track:
http://www.waleswest.com

Fred-

I fixed a pinhole leak in a copper boiler by using a center punch at an angle to force the hole closed. Did this several years ago, holding up fine. I would try that before using soft solder.

-Larry

Ginger (yes, ginger, not Maryann) can fix pinhole leaks, although yours is in the steam space and not the water space, so I'm not sure if it will work.

Steve

DO NOT SOFT SOLDER

if you do - you are screwed forever.

Once you put soft solder in there, you can forget fixing it properly with silver solder later.

I am almost finished boilding a new boiler for a friend in just such a situation.

Ginger works somewhat, but you will have to keep adding it forever....and as said, may not truly work in steam space - and the same thing applies - once you put it in there, properly fixing with silver solder becomes a problem because of contamination

Were it me, I would take it apart (remove boiler) and fix it right and be done with it.

But then I don't screw around with boilers.

It is just time and oxy / acetylene to fix it.

Ginger will work... Been around as a remedy for years....

But your engine will smell like a ginger bread bakery while under steam!

LL

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I think Larry offered the best solution - mechanically caulk it. If you can, back the area up with a heavy bar. With a dull punch move the metal around the hole inward to close the hole. Don't hit the hole directly, hit about 1/16" away from the hole.

If you REALLY don't want to resolder it, you MIGHT consider this solution in addition to mechanical caulking:

1> pull a slight VACUUM on the boiler.

2> clean area good with acetone. Ensure stuff gets inside the boiler through the leak also. You can test this by smelling the vacuum pump exhaust for acetone odor.

3> Use HIGH TEMPERATURE LOCTITE around the leak (good for 200 C or so). Again, smell the vacuum exhaust for loctite odor to be sure it gets sucked in.

4> let stand for a while (do NOT be in a hurry)


I worked with a fellow years ago that intentionally sealed his screw-in stays with loctite. I wouldn't do it but I know it works.

And why, praytell would you not soft solder it? You're fixing a leak on a 80-100 psi boiler, which is well within the capabilities of a lead bearing soft solder to remain as a solid with enough strength to act as a caulk.

I have a boiler downstairs that is completely soft soldered. (and stayed, so the soft solder is strictly a caulking). It was a fairly common pre ww2 method of building boilers, particularly for 60 psi or under. If the boiler is a 125 psi job, then I would be more tempted to reach for oxy, but...if you re silver solder it, expect that you will move the leak around rather than fixing it.

The important concern from where I sit is that the soft solder must be purely seen as a caulking medium, and not providing any strength at all.

Been there, got the T-Shirt, and have a couple of boilers where soft solder has been used as a caulk, and one engine where someone used soft solder where he should have used silver, and that causes me grief. (the injector occasionally just falls off...)


I will note though, that once you soft solder on the boiler you will NEVER be able to silver solder in the same area. The lead/tin (I understand the lead) will prevent silver solder from penetrating the surface metal & so silver solder will no longer be a useable cure around that area.

James Powell

As I said...

If you soft solder and then for whatever reason in the future need / want to use silver solder again, you are screwed.

As for using solf solder for a primary caulking method - well - I wouldn't.

It may have been accepted before WWII, but I have 50# of junk boiler sitting in my basement that was soft-caulked in 1966 and totally unusable today.

Drill a hole, exactly through and in-line with the leak.
Size? Tapping size for the smallest thread you can manage.

Tap said hole, with a taper tap, but DONT tap right through, just so the outside is tapped.

Then screw in copper bolt/screw/stud to that it "bottoms out" on the untapped portion of the hole.
Secure with high-temp Locktite, or else coat with Comsol (high temp soft solder) if you are sure you will never need to silver solder in that area, or even silver solder it in place.
(Obviously, you need to do one of the above before screwing it in.)

Even if you just screw it in, it will fix the leak provided you have only part threaded the hole, but better safe than sorry.

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http://www.alanstepney.info
Model Engineering, Steam and workshop pages.

Alan:

Your technique is excellent and will work unless..

The leak is a crooked hole, going many directions - or porous solder job?

Leaks don't always have to run radial inside to outside.

i beat on it today and i think i have it sealed. as i peened it the leak moved a bit. i think it was going past the peeened area looking for a way out. i put 60# air pressure in it and used soapy water on the area and no bubbles.
i plan to take it to the track next weekend for a first run.
wish me luck,

_________________
Fred V
Pensacola, Fl.
home track:
http://www.waleswest.com