Leaking Steamer Boiler

[fixbear]

Never worked on this particular machine,  But I do have boiler experience in regards to testing and certification.  If you shut it down and let it cool you can take a hand pump with a accurate gauge and shut off,  fill it to the top with water.  Make sure to vent  all air.  Pump up to relief pressure and wait. Note relief pressure. pressure will drop below relief closing and you can then come back up to just below it.  Your leak will weep.  To actually test a boiler,  one would remove all covers and shields.   Remove the safety valve and plug with a second gauge,  tee, and bleed valve.  Then pressurize to 150% of working pressure. Slowly while listening and observing for any abnormal movement or distortion.  Abort if there are any.  Sometime’s internal boiler stays break on a boiler. Condemning it to scrap or repair by a certified agency.. Close off valves and watch pressure to drop over time. Minimum of 20 min. If pressure drops you have a leak.  And should be able to find it to make corrective action. 

 

On a side bar, There are some boilers that are not ASME certified.  Look at the tag before testing.  These will often only be pressurized to 120% of working pressure.  Tag should be welded on to the pressure vessel with working pressure and test date.  Often with test pressure.

 

I suspect you may find one of the fire tubes has failed.  It’s the weakest point of a boiler due to the constant expansion and contraction.

[olivero]

Thank you for the reply Fixbear,

 

I figured the exact boiler is not all that important.

 

I can definetley hear the leak hissing away, no doubt there is one somewhere

 

I thought about the fire tubes as well but couldn’t quote see how that would make the leak audible as it may crack the tube at which point you could flood the burners or if its above the water, wouldn’t really do much.

 

Knowing my luck with my equipment, this is going to be some crack or something similar in the tank.

 

Then I’ll get to weld it up and pressure test it, what a day, what a lovely day.

[guest]

I’ve had a run in or two with these units. The hissing and short cycle indicate a leak. Check around the sight glass fittings for leaks. Although it wouldn’t necessarily hiss, check the thermostatic trap(s). If the lines between the trap and drain are hot, once its been running for awhile, the trap will bleed pressure off.

 

For a boiler leak, break out your inspection mirror. look around the boiler tubes on the bottom above the burners. If its leaking from the top, its gonna be harder to find. Take the mirror around the insulation panel  and see if it fogs up. It might narrow down your search. Has this unit been descaled recently?

[olivero]

I’ve had the sight glass leak in the past, I’ve gone through all the various hose connections as well as the compression/flared connections and I have come up dry handed. 

 

I figured if its the flame tubes, they would be dripping water into the burner if it was below the water level, I can also hear the hiss which makes me think the boiler is leaking since no other connections are.

 

I did try to run a mirror along the top insulating panel and the mirror did fog up in one particular corner, I could also feel a lot of heat eminating from that area.

 

Yes, about a year ago and both anodes replaced, I checked the boiler about 2-3 months ago and it still looks good.

 

Just not sure how much of a mess I am going into with having to check the boiler top since the steaming compartments are sitting right on top of it. I am guessing i would have to dismantle this unit pretty much entirely to get to the boiler.

[fixbear]

If your leak is below water level,  It would sputter and flash to steam.  Not just hiss.  Possibly top tube sheet to either tubes or housing? 

 

Is the steam coming out the gas vent?  Or top outside the boiler. If tube sheet it would come out the venting area/stack.  Being a rectangular boiler with square corners, there has to be a lot of expansion stresses.

[olivero]

Right, it would be pretty interesting if it was below the water.

 

I think its a corner, I can’t SEE the steam, that’s the problem. I think I have to pull the whole thing off, covers and all to find it. Just can’t decide if its worth it if the steam leak is small, which it seems to be.

 

When I listen around the boiler, I hear it the most close to one of the corners, not so much everywhere else.

[fixbear]

The most logical stress area is at the top of the sidewall in a corner just below where the tube sheet is welded in.   The corners are where the most stress will be..  I hate square boilers. always best round.  I also hate stainless for any pressure vessel. A285 grade C copper bearing steel is the bast for boiler use.  I’ve made and repaired a few in a past life. Problem is it can only be rolled one way due to the grain.  There is no stainless that is totally good for pressure vessel use. They all fail at some point… That’s what sunk the Thresher in the 60’s.

[olivero]

Yeah, makes sense.

 

Hopefully whenever I do tear this unit apart to find it, I’ll be able to weld the crack up and get it back in use. 

those boilers are probably not cheap.

 

Have you ever had to expose the boiler on one of these units? I would like to get some info on how much work it is to expose it, seems like the entire top (where the compartments go) has to be taken off and the boiler disconnected from gas and water and then hauled up and out of the base. 

[fixbear]

Olivero, I believe it may slide out the rear of the frame.  They became rare In my area when the state labor started registering them and requiring a annual boiler inspection. And the addition of low water cut-off back-up system. Some of there inspectors are not to good with common sense. But they collect there fees.

[moldypickle]

Olivero,

We had the same steamer here at my facility.   Had the same issue.  The original call was for flame failure.  It was dripping down on to the ignitor once it came up to pressure. I could also hear the hiss but couldn’t tell where it was coming from.  We decided to order a new boiler to the tune of around 5 grand if I remember. Pulled the steamer from the kitchen and disconnected everything from the boiler.  The leak was coming from the weld around one of the flame tubes.  Also had corrosion.  We actually found it was easier to bend 2 tabs down at the rear of it and pull it through the back of the steamer.  I’m not sure if that was the best way but seemed the easiest.   I think any way is a huge job to remove that boiler.  FWIW, we have since removed that unit due to corrosion issues around the steam tubes in the cabinets.  We have replaced it with the groen  ssb-10G.  Boilerless.  As far as I’m concerned in 2 years the only breakdowns  I’ve had to fix were replace a handle and clear the drain.