Air leaking by cooper tubes

[lighthousekeeper]

Hi, I have a vertical tube dry leg boiler there are 22- 1 1/2" copper tubes I noticed a slight hissing noise when I fired up the boiler yesterday for the first time this summer. I had a great run on Jenny Girl we steamed for 3 hours none stop. I was running at 80psi but noticed pressure dropping to 60psi as I approached home. Today went to fire up boiler I could not even get 20psi and the hissing was a lot louder.

So I pulled boat out took top shroud of boiler off connected air to boiler and used a soapy solution and around just about every cooper tube I was loosing air.

So my question is there a way to tighten these tubes or do they need to be replaced?

thanks,

jamie

[Mike Rometer]

Assuming they haven't been overtightened before there is indeed a tool to roll them tight. It's called a tube expander, It usually has three rollers and a tapered mandrel. Not particularly cheap and you need the right one for each tube size. Google (other search engines are available) Boiler tube expanders and you should find a supplier in your preferred location.

[lighthousekeeper]

Hi thanks for the info will I be able to reach the bottom of the tubes about 30 inch's in length with a tube expander also? there isn't a terrible amount of room in the fire box.

jamie

[Mike Rometer]

No, you'll need to do them from each end. Ideally they should only be expanded sufficiently to stop the leaks and no more (so there's some left for next time). Like all these jobs there is a 'feel' for it.

[lighthousekeeper]

Actually I think the bottom ( fire box side) of the tubes is fine being submersed in the boiler water. Can you tell me why some guys just roll the tubes in while others silver solder them?

[cyberbadger]

Ross Bendixen poking up his head again. My Bendixen boiler never had this particular issue. I had one small firebox tube weep from my ASME code boiler, but it went away on it's own.

It can be like wack-a-mole though - if you have lots of tubes leaking it's going to be hard to get them all steam tight again.

You tend to have the sympathetic neighbor problem. You reroll a tube, and then an adjacent tube can decide to cry too... It can drive a steamer mad, because it might only reveal this under steam. :/

For reference ASME code boilers can be rolled+bead OR welded. The ones on my ASME boiler for Nyitra are rolled and beaded steel. Copper is not allowed I believe for ASME code boilers except for .copper ferrules at the end of the tubes to help exactly with the problem you are facing.

However copper can certainly be used for non code boilers. I think Bendixen is using the wrong copper tubes however. Type L vs Type K.

I tend to think of silver soldering as something for quite smaller boilers or small service lines only. Correct me if I am wrong on this one....

-CB

[DetroiTug]

Sounds as though the upper tubes are being overheated- scorching.

How to fix the leaks, McMaster Carr has or had tube rollers. As Mike says, take it easy with the roller, just want to roll enough to stop the leak and that's it.

What's causing it? May be running the water too low, allowing too much exposed tube in the top. Over-firing it with too hot of a fuel. Laminar flow allowing hot gasses to pass the steam generating portion of the tube, turbulators can help with that in the steam generating (lower) portion of the tube only. A turbulator is just a flat strip of steel twisted and hangs in the tube from the top. They should not extend all the way up the tube though, should only run from the bottom to the normal water level.

-Ron

[lighthousekeeper]

I have been running with 40% to 50% level in boiler, I will have to get that up to maybe 75%

[DetroiTug]

"running with 40% to 50% level in boiler"

That is too low. A typical VFT Should be in the 70% range - upper portion of the glass (if it's located properly). On a few occasions I have ran the tug low water level trying to get steam back up and the upper boiler got very hot. Had one of those sight glasses with the red lines on it that is steam rated, and it burnt the lines off the glass.

A handy thing to have is an infrared thermometer, and they are pretty inexpensive nowadays. You can shoot the funnel and see what the flue gas temperature is on exit. It should be somewhere just north of 300 degrees. If it's 450, 500 etc, the heat is not going to the water and turbulators should be added.

-Ron

[cyberbadger]

On my boiler from Ross Bendixen the sight glass was misaligned and low.

I had my steam mentor use a magmount drill to make the sight glass full length so I could really see and operate at a safer proper level and use the tri-cocks properly. Ross has since fixed the tricock alignment issue, but his glasses are still placed too low.

Ron is right. 70% or more is where you should be. You just don't want it so high that you get carry-over. Other then carry-over the higher the better. The water will keep the tubes cooler and conduct the heat to the water which is what we are all trying to do. A Boiler is in essence a glorified heat transfer device.

-CB