Fitting/Bushing/Boiler Question

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Fitting/Bushing/Boiler Question

Post by Shlick88 » Wed Jul 03, 2019 5:31 pm


I could really use some major help! As I've mentioned in some previous posts, I recently inherited a locomotive I'm been working on. However, the advanced maintenance and "machining" are all new to me. I noticed this fitting into the boiler had a crack, so I decided to remove it but for the life of me, I can't find the right part to replace it.

Long story short, the fitting measures 3/8" OD that needs to screw into the boiler. The fitting needs to have a male and male thread. The male end pointing out of the boiler needs to be threaded to fit into the elbow which appears to be 1/4" ID. So I'm needing a part with a 3/8" OD male x 1/4" OD male. Does this make any sense? Not sure if I need a bushing, union, etc....

FYI- This is the line from the injector to the boiler. I'll answer any questions and take pictures/video if needed. Would really appreciate as much help as possible. You guys have been great in the past so thank you in advance for your help!

Burlington Little Line
4-6-2 Pacific 1.5"
Omaha, NE

Soot n' Cinders
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Re: Fitting/Bushing/Boiler Question

Post by Soot n' Cinders » Wed Jul 03, 2019 5:47 pm

PM Research will have the fittings you need. To me, it looks like all you need is a 1/8in NPT to 1/4in MTP reducer bushing and a 1/4in MTP close nipple

-2.5" scale Class A 20 Ton Shay

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Re: Fitting/Bushing/Boiler Question

Post by Fender » Wed Jul 03, 2019 7:20 pm

What caused it to break? Could it be because of unequal expansion between the boiler and the injector piping?
Dan Watson

Glenn Brooks
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Re: Fitting/Bushing/Boiler Questio

Post by Glenn Brooks » Wed Jul 03, 2019 8:00 pm


Welcome to the hobby! Lots of interesting things to see and do while you figure out how your new loco is put together. Don’t hesitate to ask any questions you need - we’ve all gone through the learning curve, more than once usually. And there are a lot of talented and helpful folk here on Chaski that can help out.

Regarding your boiler fix, I’ve found this is a fairly common point of failure on the boilers I have owned. The small diameter nipple that comes out of the boiler gets exposed to all sorts of stresses, often through tightening, leverage of the injector line, etc. Particularly if the fittings are yellow metal (bronze or brass), they will eventually crack and brake, after you wrench on them once to often. Sometimes the metal just fatigues from old age and usage, then breaks off every 10 years or so. I now use black iron pipe fittings rather than brass, as bronze has become impossible to find anymore, and black iron pipe fittings seem to be more durable.

Any decent hardware store should be able to outfit you with replacement fittings - although 3/8” aren’t common anymore except for use in commercial sprinkler systems. But you likely won’t find decent boiler hardware at these big box DIY places, like Home Depot- ideally you should locate a local steam supply house, or find an actual old time, industrial grade hardware store, with sales staff that have actually worked with plumbing supplies.- not just stock volumes of plastic blister packs on a peg board.

Also I would recommend taking the 3/8” fitting out of the boiler, and take both pieces into a hardware store so the plumbing sales staff can physically see what you trying to replace.

As a side note, Personally, can’t see why you would need to mail order something like these fittings, when they’re usually quite commonly available.

Also, if you edit your Name block that appears in every post, and add your location, it will help other forum members better answer your questions regarding suppliers. Each region has its own speciality stores and unique operating conditions. People that live in your area often can recommend better fixes, based on their local knowledge.

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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

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Re: Fitting/Bushing/Boiler Question

Post by Shlick88 » Sun Jul 07, 2019 5:51 pm

I appreciate the advice guys! Was out of town over the weekend but ready to get back to work. Planning on stopping by a few hardware stores this week to see if someone can't help me out. I'm sure you haven't heard the last of me as I'll take as much input as I can get being new to this.
Burlington Little Line
4-6-2 Pacific 1.5"
Omaha, NE

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