I have a case where an engine with brass check valves that will absolutely not come apart, nor have they been disassembled for some time (on a working engine).

Are there any tricks to get brass threaded steam fittings apart. Also, what is recommended to keep the threads from seizing when assembling fittings?

Michael Seitz
Missoula MT

You could try a good soaking with Kroil, let it sit overnight, heat it a bit, thump it with a hammer and soak it again and let it sit. Heat again and try it now. I always had good luck just heating one side of a nut or fitting and then trying to loosen it. For some reason, I guess it would heat unevenly and deform for a minute and that may have been enough.

The only time I had trouble with brass fittings were brass washout plugs on steel boilers. Most brass comes apart pretty easily from my memory. With the brass threaded into a boiler or another steel fitting, you may try heating the surrounding area of steel to break the crud free {not sure how to write that part}. Most parts are not left handed threads and I don't mean to sound smart about anything, but are you sure your not turning the wrong way? May sound fundamental, but it has happened to others. I don't like heating brass fittings too much, brass on brass should come apart. Brass on steel, heat the steel. Probably not correct thing too do, but years ago we would then douse the heated steel area with water to help rapid contraction to help break the threads from the crud. An old boiler maker showed us how to get stuck washout plugs out this way. It worked, though I am sure someone would disapprove. Good luck, John.

If it is brass screwed into steel I have heated the steel part and then melted ice cubes on the brass part. You may have to do it several times. Turn the brass while the steel is still hot. I don't know if this is the "right" way to do the job but it has worked for me.
John

Be careful.....I have had some grades of brass fittings crumble after being heated to loosen them. It was an unpleasant surprise. Might want to limit heat to enough to expand, but not to glow red. If you notice the bands of oxydation color changes run out of the heated area it is probably about there.

Reading the inquiry, it sounds like the issue is brass cap removal from a brass check valve casting.

I use a catalytic penetrant called PB BLASTER because it works and is available at local auto supply stores, or from McMaster Carr. I've used KROIL, but find it doesn't capillary as well as PB, especially uphill. Others may have had different experiences.

It is possible that something like EXPANDO might have been used as a joint compound - if so, a large wrench tensioned than sharply rapped with a sledge might break the joint loose.

In reassembly, the traditional formula was a syrupy paste made of powdered graphite in steam oil. It seals well in a steamy environment and acts as an anti-sieze. Proprietary steam fitting joint compounds are available if you'd rather get a modern equivalent.

Worst case scenario, wreck the cap and protect the valve body. A decent machinist can knock out a new cap in an hour on the lathe, less if is a simple thing with no shutoff stem to deal with.

Good luck.

dave

Be careful heating any part of the boiler shell, you risk burning the metal which will induce cracks down the line. My process for removing cleanout plugs is to heat the plug just until you begin to see the torch flame give off a green color. Stop there and pour some cold water on the plug only. After a minute or two it should thread out with little effort. As said earlier, if bronze is heated too much, it could disintegrate when wrenched.

Chris Allan

I should have been more explicit about the heating part. NEVER heat brass or bronze red, just heat to about 200-300 degrees which is enough to expand it slightly and break the crud loose. Make sure your wrench fits well or you will have another problem.