Leaks Allowed?

[Big Northern]

Does a concensus exist regarding slight boiler leaks? Seems I have seen both prototype as well as scale models belching steam from all angles sometimes!

Should boilers be absolutely leak-tight? I lean towards a "yes", myself, but really don't know! BN

[Soot n' Cinders]

It depends on where the leak is in my opinion. Turret and steam valve leaks are no big deal. Flue leaks are a bit more concerning, again depending on where its leaking. Where the tubes are rolled in, a little leak is acceptable as more rolling or a little peening will usually remedy it. Welds in the shell are a step up from there, pin hole leaks are easily fixed with any number of solutions. Cracked welds leaking, or a leak somewhere in the middle of either a flue or elsewhere away from a joint are enough to warrant removing the boiler from service. Again this is all my personal opinion, others may have different views and actual mileage may vary.

[gwrdriver]

Technically, if a model boiler has a leak it won't hold pressure and it can't pass the hydro can it.

[Big Northern]

Technically, if a model boiler has a leak it won't hold pressure and it can't pass the hydro can it.

Good point! But is it possible for no leakage to be detected by pressure drop during cold hydro testing, while under heat and steam pressure, a leak might then show up? BN

[James Powell]

Technically, if a model boiler has a leak it won't hold pressure and it can't pass the hydro can it.

what hydro?



OK, our full sized rules were 10% drop over 20 min. (60 lb/20 min). There was still some air in the boiler for a normal test...so, usually it isn't that hard to pass.

The answer is "it depends", it depends on who is doing the boiler inspection, and what they are concerned with using the hydro to prove. If the hydro is to prove the boiler is tight, it is a different case than proving that the boiler is strong enough. A boiler can be plenty strong enough, but totally unable to have a hydro or get steam up. (then it probably would be called "failed"...). The tubes on Little Johnny are a bit weapy, but I am quite happy with them. I know what the cause is, and have a fair idea how much life the tubes have left. Since I don't at present have a club certificate, or any requirement for a provincial certificate (I now hold a 3rd class power engineering ticket...), I am good. If I was a member of either club here, I might run into other issues, but for now it is fine.

James

[wmegilljr]

At our club in Boulder City we hydro the boilers to 1.5 times the lowest safety valve and have the rule "no leaks on the pressure vessel" that includes the water glass. But any appliances that can be valved off can be closed. That's not to say that tubes cannot weep a little at the sheets as almost all small tube weeps seal when heated. I have heard that some clubs allow you to close off the water glass for hydro, but that defeats the purpose of checking the "entire" pressure vessel. If your glass cannot pass with the boiler it should be repaired or replaced. Just my 2 cents I know many will not agree.

[gwrdriver]

Historically, in model practice anyway, the hydro was intended to test the integrity of the pressure vessel only, not the fittings, and in particular the water glass. My suspicion is the "rule" that boilers be tested with fittings installed came to be because some owners were too lazy to remove the fittings and plug the holes for testing. If I was a tester (which I'm not) I would have to say "If you want to submit your boiler for its test with fittings in, that's OK with me, but if a fitting leaks the whole boiler fails." Otherwise how do I know the fitting is the only leak? What bothers me more than all of this are under-trained and over-zealous "Inspectors" who insist upon going beyond the 2X and 1.5X while banging on the shell with a hammer! Usually because they read this is how it's done in their copy of "Modern Boiler Husbandry for the Railway Mechanic 1877."

[cbrew]

What bothers me more than all of this are under-trained and over-zealous "Inspectors" who insist upon going beyond the 2X and 1.5X while banging on the shell with a hammer! Usually because they read this is how it's done in their copy of "Modern Boiler Husbandry for the Railway Mechanic 1877."

hmm, i would hit the inspector on his shell if they tried this!!

[Hudson Honey]

I agree with Chris here.....beat on my boiler eith a hammer and we have a serious problem.



Pamela

[FLSTEAM]

I agree with Chris here.....beat on my boiler eith a hammer and we have a serious problem.

Actually this is common practice to test any pressure vessel.

Unless the inspector uses the "Ball" end of the hammer there should be no damage to the shell.

John B.

[Fender]

Actually this is common practice to test any pressure vessel.

Unless the inspector uses the "Ball" end of the hammer there should be no damage to the shell.

John B.

Years ago, a fellow live steamer submitted his Little Engines 1" scale 0-6-0T boiler with a cast bronze firebox to the Virginia state boiler inspector. After performing a hydro test, the inspector passed the boiler, then proceeded to stamp it with the state id number using a large hammer and punch, which produced deep dents in the firebox casting! So a little tapping with a hammer seems pretty benign by comparison!

[cbrew]

ok fine, how many here remove the jacket every year for the hydro?

because of the jacket, the only place that could be hit with a hammer is around the firebox door?

i repeat my stance. no one will touch my boiler with a hammer..