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Post by sncf141r on Apr 23, 2014 22:25:10 GMT
Ok - It *is* boiler fittings time, at long last.
3-1/2" gauge locomotives. (two of them)
Two Questions:
1) Brass or Bronze for fittings like safeties, valves, etc. I hear both. Why not brass?
2) Valve handles to valve spindles - thread handle, lock nut, square hole in handle, press fitted, square hold in handle, with lock nut, or just silver soldered?
(I have "square/pressed", "threaded/locknut", and Kozo Hiraoka specifies silver soldered for his locomotives)
Looking for collective wisdom here!
Another JohnS.
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Post by Deleted on Apr 23, 2014 22:43:28 GMT
Don't use brass for boiler fittings. It can/will suffer from dezincification. I've had several fittings snap off due to this when I've tried to remove them from an older boiler. Could have been nasty if it had happened in service. I always use bronze.
I've used valve stems where the handles are threaded with a locknut but they can come unscrewed if the valve sticks. The best is probably the square hole in the handle with a nut to hold it on. I don't think I'd silver solder them on as you wouldn't be able to remove them again.
John
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Post by ejparrott on Apr 23, 2014 22:44:39 GMT
Bronze fittings, never brass, the zinc comes out and the fitting crumbles away.
Square spindle on the valves, sqaure hole in the handles, with a nut to stop the handle falling off - never tap the handle and expect a nut to lock it.
Or do what I do and buy your valves from AK Railways in America, who already use the square drive system and save faffing around making fittings.
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jma1009
Elder Statesman
Posts: 5,901
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Post by jma1009 on Apr 23, 2014 23:07:28 GMT
hi john,
ive some quite old locos that have seen a lot of use, and rebuilt some even older ones eg club locos and others for friends.
my own personal thoughts of course re the following...
valve handles to spindles - the spindles should always be of stainless and fitted to the handles on tight fitting squares. valves in the UK must now be captive therefore you cant silver solder the handles to the spindles. whether you add a small thread on the end of the spindle for a nut as well is a matter of taste and IMHO unnecessary. for GWR handles i make them out of stainless with tufnol handles.
brass or bronze for boiler fittings - below the water line they should ideally be of bronze but if made of brass will take at least 20 years to be affected by de-zincification in my experience. blowdown valves should be captive as per above and be careful because i have yet to see any commercially made blowdown valves which are captive. virtually all LBSC type boiler fittings sold commercially are brass.
i use brass for all fittings above the water line. some of the fittings on one of my locos are 50 years old and show no sign of de-zincification despite being made of brass (they were all removed and inspected 2 years ago). i know that in theory bronze would be preferable throughout but all the brass ones are perfectly ok. that includes all safety valves.
of more concern is what stainless grade you use for regulator rods. i had one loco a few years ago where it had seen very little use but the magnetic stainless rod had corroded very badly. i only use austenitic non-magnetic stainless on boiler stuff and the same goes for check valve balls.
i think there is something to be said for having something below the water line that is brass to in effect de-zincify and which can easily be checked at intervals and if necessary replaced. i believe this was RN practice on boilers.
all screws, bolts etc to be of hard drawn phos bronze or austenitic stainless.
cheers,
julian
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Dave H
Involved Member
Posts: 91
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Post by Dave H on Apr 23, 2014 23:13:23 GMT
Are we talking Boiler Bushes or actual Fittings here? if Brass is such a no-no as implied here, why do the major suppliers of Fittings, ie - Blackgates/Reeves/Maxitrak/Polly etc, supply the majority, if not all of their fittings made of Brass? or am I wrong in this statement! Confused, most certainly!.
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Post by Deleted on Apr 24, 2014 7:56:13 GMT
Are we talking Boiler Bushes or actual Fittings here? if Brass is such a no-no as implied here, why do the major suppliers of Fittings, ie - Blackgates/Reeves/Maxitrak/Polly etc, supply the majority, if not all of their fittings made of Brass? or am I wrong in this statement! Confused, most certainly!. Fittings. I presume most ME suppliers sell brass fittings because that is what their suppliers use. It probably boils down to cost and brass is easier to work with. How long they will last probably depends on water quality, how often the loco is steamed etc. There are also many sorts of brass which will affect it's suitability for our use. Maybe other different metals used in the boiler may cause electrolytic action that will speed up the dezincification process e.g. the wrong sort of stainless as Julian suggests? If you intend to use commercial fittings then I suppose your stuck with what you can get but if you're going to make your own why take the risk, use bronze or gunmetal. The difference in cost will be negligible for the amount of material that you are going to use. You probably can get away with brass for 'chunky' fittings like safety valves as there is usually a lot of metal where the fittings are threaded and they're only exposed to steam rather than water. Some valves for example are quite flimsy on the threaded parts though and it doesn't take much dezincification to seriously weaken them. It's a bit like the stainless boiler debate. Some say they are a no-no, some say they are ok. Yer pays yer money and yer takes your choice! One of the fittings that broke on me was a blowdown valve on a boiler that was not that old and hadn't done a lot of steaming. This is a pipe nipple that snapped from the same loco. There were a lot of mineral deposits in the pipe which probably didn't help though. Our water at Coalville is pretty awful stuff!  |
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Deeja
Seasoned Member
Posts: 131
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Post by Deeja on Apr 24, 2014 9:54:56 GMT
Any thing soldered into the boiler (bushes etc for the dome, firebox door, fittings etc) MUST be bronze. The actual fitting that screws into these bushes can be either brass or bronze, and the comments in the above replies are mostly applicable to those fittings. Bronze is probably the better choice (if you have a choice) but brass is OK too, albeit with possible dezincafaction and resulting brittlesness after a long time.
Deeja
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Post by Deleted on Apr 24, 2014 12:00:14 GMT
"It probably boils down to cost ........... "----------- Oh dear, John, that's awful !!  |
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Post by Deleted on Apr 24, 2014 13:56:27 GMT
But unfortunately, no doubt true  |
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nonort
Part of the e-furniture
If all the worlds a Stage someone's nicked the Horses
Posts: 277 
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Post by nonort on Apr 24, 2014 16:08:55 GMT
JMA will put me right but i think Don Young specified a grade of brass he used for his fittings. Can't remember what grade it was though.
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Post by Deleted on Apr 24, 2014 18:10:21 GMT
This might be useful. It appears there is a type of brass that is resistant to dezincification: Brass SpecificationsJohn |
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Post by Doug on Apr 25, 2014 7:00:19 GMT
Our water at Coalville is pretty awful stuff! You should see what it does to the people  |
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Post by Deleted on Apr 25, 2014 8:06:46 GMT
---------------Bright, intelligent, outgoing, fun-loving  OR}-- Jaw-dropping, knuckle-dragging, Neanderthals uttering the word RED backwards all the time ..  ..  ........... |
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Post by Doug on Apr 25, 2014 11:06:20 GMT
---------------Bright, intelligent, outgoing, fun-loving OR}-- Jaw-dropping, knuckle-dragging, Neanderthals uttering the word RED backwards all the time .. .. ........... .....Probably not the first one  |
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