|
|
Post by johnharkness on Nov 3, 2004 20:00:50 GMT
Hello again,
Does anyone have any gen on getting a boiler certificate for this loco. The boiler inspector at our Model engineers club isn't quite shure about how things stand today. The boiler is built to LSBC design,problems are the backhead fittings have no bushes in the backhead, theres no bush in the boiler barrel where the top feed clack valve is, they are just threaded straight into the copper barrel. He wreckons that all boilers have to have bushes inserted?. Also the boiler barrel is riveted and a fillet run inside the boiler where it is joined. Shurely there must be a lot of LSBC designs at model clubs in use today.
|
|
Garry
Active Member
Posts: 45
|
Post by Garry on Nov 4, 2004 8:16:36 GMT
Hello, I bought a loco a few years ago, about 5, and it did not have a blow down fitted and I discussed the matter with our club boiler inspector. My problem was I would not be able to get enough heat to silver solder a bush in the lower firebox region so he said it would be acceptable to thread a large hole in the copper and screw a bronze bush in place and then soft solder with comsol. This was done and the loco has been in use frequently at our club and portable track events without any problems from the fitting. The loco has passed 2 boiler inspections since then. I think you should talk to your inspecter and see if you could do this. It should not take long to make all the bushes needed and it is a lot easier to soft solder them in. DO NOT SOFT SOLDER THEM UNLESS THEY ARE THREADED INTO THE COPPER FIRST.
Garry
|
|
|
|
Post by Roger Mason on Nov 4, 2004 16:53:51 GMT
Hi,
The argument regarding bushes or no bushes is an interesting one.
If the bushes are threaded and soft soldered, the solder is only there to caulk the joint - it does not add any strength, unlike silver solder. In this case, surely the smaller the diameter the bush the less force there is from the steam in the boiler trying to strip the threads.
If you take this to the extreme then fittings tapped directly into the boiler are safer than larger diameter bushes tapped into the boiler to take the fitting?
Any thoughts?
Cheers,
Roger Mason, in St. Agnes
|
|
|
|
Post by greasemonkey on Nov 4, 2004 23:04:13 GMT
Hello
Having looked through what information I have to hand I can see nothing to say that a riveted and soft solder chalked boiler is unacceptable. If it appears to be sensibly made and and passses a hydraulic test then you have to trust it is sound. I have seen silver soldered boilers fail hydraulic tests due to poor soldering that visually appear fine.
What I would say though is that I would run it at no more than 80 psi max, for 2 reasons. The first is in defrence to its age and secondly that if you look at the temperature of water at 80 psi it isnt that far of the melting point of soft solder. Finally it might be worth checking the boiler fittings for dezincification particuarly if the are of the same age as the boiler.
Andy
|
|
|
|
Post by johnharkness on Nov 5, 2004 18:27:33 GMT
Thank's for the info guys, has anyone had a LBSC design boiler pass for a boiler cert without the bushes recently and is there any laws laid down in black and white about this?.
|
|
|
|
Post by alanstepney on Nov 5, 2004 20:08:52 GMT
The main legislation governing boilers are the Pressure
Equipment Regulations of 1999, and the Pressure Systems Safety Regulations (2000).
There is a concession that allows Model Engineering Societies to examine and test boilers and to issue certificates, which are then accepted in other clubs.
As it is a concession and not a right, it is up to the individual testers whether or not they accept any specific boiler.
Remember, if something subsequently goes wrong, they have put their heads on the block!
Hence most tend to be cautious.
Having said that, I am sure that some will pass LBSC designs as they are, whilst others may not be happy about some feature or other.
|
|
|
|
Post by the_viffer on Nov 5, 2004 21:29:13 GMT
I'm not a boiler tester Alan (thank goodness) but if I were I think I'd take the inconsistent view that for an old boiler I'd growl at fittings directly tapped into a boiler shell but refuse them on a new boiler.
My recollection of the Southern Fed regs is that directly tapped fittings are not automatically excluded. They (that is to say directly tapped fittings) are rank bad practice and the Southern Fed rules are minimum requirments and as you say testers are at liberty to impose stricter standards.
There is a school of thought that says that a soft solder caulked boiler is safer than than an all silver soldered one as over heating will allow leakage but not explosion. I find it attractive. However I have always replaced such boilers with all silver soldered ones and while I may have worked for nearly 20 years in engineering my background as Alan knows is in chemistry and doing James Herriot impersonations.
|
|
