What gauge tube?

FortyTwo · February 2020

Hi All,

I'm looking to re-tube my Federal FST-50 (one pipe steam/dhw) in a few days hopefully and wondering what people's thoughts and preferences are on tube gauge to use. In the past I have done both 10 and 11 gauge but never done a full retube so I can't gauge the the difference easily. I usually do 10-25 tubes and then another round of that the next year. This time I think I'm going to do the full thing even though I only have about 10 plugged right now.

The new tube guy I plan to use recommends 11. As I understand.. 11 will heat quicker and save fuel, and 10 will last longer. Is that a correct statement?

The boiler water is not treated. I am trying to learn more about treatment and may treat it if I can afford it. With it being a nice fresh start, it would be great if I can. I do have a tight budget though and may not do that or get to that for a while depending on what is involved.

Thank you!

EBEBRATT-Ed · February 2020

I wouldn't use a gauge any thinner than what the mfg recommends

nicholas bonham-carter · February 2020

Have the water tested before treatment. Additives will interfere with the steam generation.
Most rusting occurs because of too much fresh oxygenated water being added to replace that amount lost because of a leak. Water softeners are also a no-no.--NBC

FortyTwo · February 2020

@nicholas bonham-carter

I thought water treatment was good? And won't water always leave the system and need to be added? Some of the return runs are pretty long and underground and I have replaced sections but it would be a massive job.

ScottSecor · February 2020

We typically use 10 gauge, I've seen our competitors use 12 gauge and they seem to hold up pretty well. I'd recommend spending a few more dollars and spring for the 10 gauge.

I also recommend cleaning the water side of the boiler once the tubes are removed, there is often a lot of debris and rust in the bottom of these boilers.

FortyTwo · February 2020

@ScottSecor
Thanks! I'll ask them to do that. How is that done? Hosed down and scraped up a bit or something?

You don't think I'd be spending much more on oil with the 10 gauge over 11? 12 is too thin. It's a hefty oil bill there so I'm torn.. the tube replacements are always annoying and stressful.

ScottSecor · February 2020

If the ten gauge lasts ten years and the eleven gauge lasts eight years that is a twenty percent increase in longevity. I'm guessing your fuel bill would increase incrementally from the thicker tubes. In my mind reliability outweighs saving a few dollars on fuel, your needs may be different.

I would recommend at least a real good rinse with a garden hose, ideally a power washer shot through the tube sheet (with the tubes removed) and shot though the hand-holes and man-holes. It's bees years since I did it myself but I can remember pulling a few five gallon pails of rust and debris from the lower hand holes on many boilers.

PerryHolzman · February 2020

@FortyTwo "You don't think I'd be spending much more on oil with the 10 gauge over 11? 12 is too thin. It's a hefty oil bill there so I'm torn.. the tube replacements are always annoying and stressful."

Go with the heavier guage... It will have only a small effect on heat transfer and your fuel bill. I'm an engineer and my specialty is tubular heat exchangers... including heat transfer through tubes. Without showing you all the equations... the biggest thermal resistance is the convection coefficients on each side (how the exhaust gases and water flow across a surface), the next is the fouling layer on each side. Tube wall thickness resistance is often only between 4 and 7% of what is slowing down the heat transfer. Changing the thickness has only a minor effect on the total.

So go for long life...

A question though: is the pitting that fails the tubes on the fireside or the waterside? or equal on each side. You should be able to see that (I know that I used to see that in old coal fired boilers when I was a kid helping the "coal man", and later when visiting railroad museums that were retubing locomotives.

I and others might be able to make some recommendations to increase life if we knew which side the failures were on.

Have a great weekend,

Perry

FortyTwo · February 2020

@PerryHolzman thank you! I feel much more confident going with the 10 gauge now. The pitting is on the water side. I'll try to get some pictures tomorrow if I have any old tubes laying around from previous tube work there and if not, when I have the job done. But it is heavily pitted on the water side.

This always makes me wonder.. is the boiler itself equally pitted like the tubes and the tube sheet? Or do the tubes attract a chemical reaction because of the heat exchange going on inside them? Puts my stomach in knots to think about changing that boiler one day.

FortyTwo · February 2020

@ScottSecor yeah I bet I have a ton of rust and debris on the bottom of mine. If love to do that, great idea. Only problem is this will be an all day job and 26 families out of heat and hot water so adding the extra step adds stress but it would be important to get that stuff out. It's always clogging my release valves to even drain the boiler. I don't think I have anything bigger than the tube holes to access that area but will look. Hose should do.

Horrible story but a few years ago I was doing a repair with my brother and he we were draining the boiler.. he slipped into the sump pit of boiling water with running sneakers on. Was only a brief moment but was in the burn ward for months

. Horrible lesson learned to always keep safety a top priority and take hot water seriously.

retiredguy · February 2020

How often are you replacing any of the boiler tubes? Do they last 10 or more years? If not, I would install a water meter on the boiler fresh water line to see just how much water you are loosing in the system. If the water loss is excessive, I would find and repair the deteriorated piping and areas where the water is being lost. The loss of water in a heating system can greatly increase fuel consumption and shorten the life of the whole heating system and the boiler. Even a good boiler treatment system, can not negate the damage done by a high amount of fresh water make-up, unless of course you have a deareator, water softner and a superb boiler treatment, which are usually way too expensive on a system of this size. A pre-heat system on the condensate tank keeping the feed water above 180F and if possible close to 200F would be very good in-lieu of a very expensive deareator. Long boiler life starts with the water consumption being as close to ZERO as possible. My advice would be to fix the water loss problem first before re-tubing the whole boiler. As far as what gauge boiler tube, until the water loss is corrected, go with the cheapest since you will be replacing them again soon. One last item, when replacing any piping below the boiler's water line only use schedule 80 steel and cast iron fittings. (no black iron , galvanized and the like).

dopey27177 · February 2020

Firstly all fire tube boilers should be treated with chemicals.

Drain the boiler completely and flush several times to make sure all the dirt is out of boiler.

Steam master is an excellent chemical to use.
Read the instructions and cut in half the amount of pills installed into the boiler. (the reason for that is the directed amount is for new installations and cause cause boiler water surging)

The boiler water should appear light blue or purple.

Fire up the boiler and see if the water level remains relatively stable. If boiler water level is bouncy drain off some water until the water level stabilizes.

Mark down how many pills were used so you will have some type of a reference point for next year.

You basically are trying to protect the tubes but more importantly you need to protect the tube sheet and boiler metal because replacing a boiler or Installing new sections of metal on a steel boiler is more expensive than tubes.

The boiler should have hand holes on the bottom of the boiler.
Two an the back and two on the front. After the boiler is drained the hand holes need to be removed and the bottom of boiler can be flushed with a water hose.

You will need replacement gaskets for the hand holes.

Cautionary Note!!!!!!

Shut down the boiler the night before to allow the entire boiler to cool down, before the contractors come onto the site open the safety valve to assure no steam can be made in the boiler, then drain the boiler down.

I consulted with an insurance company ab out the death of a worker and severe scalding of his partner in a case similar to your repair. The boiler was not shut down and given enough time to cool down. this resulted in flash steam because the boiler water was over 212 degrees when the boiler was put into an atmospheric state.

Jake

PS. if you need to replace the wet return you can do that with type K copper tubing . A lot less labor than black steel pipe.
Additionally I would look to installing the new pipe above ground using J hooks to support the tubing off the floor.

There may be some short runs of pipe that cross door ways where some of the pipe needs to be put underground. Where the tubing is put underground use clean sand to cover the tubing and install pipe sleeves where the tubing will pass thru concrete.

Jake

ChrisJ · February 2020

dopey27177 said:
Firstly all fire tube boilers should be treated with chemicals.

Drain the boiler completely and flush several times to make sure all the dirt is out of boiler.

Steam master is an excellent chemical to use.
Read the instructions and cut in half the amount of pills installed into the boiler. (the reason for that is the directed amount is for new installations and cause cause boiler water surging)

The boiler water should appear light blue or purple.

Fire up the boiler and see if the water level remains relatively stable. If boiler water level is bouncy drain off some water until the water level stabilizes.

Mark down how many pills were used so you will have some type of a reference point for next year.

You basically are trying to protect the tubes but more importantly you need to protect the tube sheet and boiler metal because replacing a boiler or Installing new sections of metal on a steel boiler is more expensive than tubes.

The boiler should have hand holes on the bottom of the boiler.
Two an the back and two on the front. After the boiler is drained the hand holes need to be removed and the bottom of boiler can be flushed with a water hose.

You will need replacement gaskets for the hand holes.

Cautionary Note!!!!!!

Shut down the boiler the night before to allow the entire boiler to cool down, before the contractors come onto the site open the safety valve to assure no steam can be made in the boiler, then drain the boiler down.

I consulted with an insurance company ab out the death of a worker and severe scalding of his partner in a case similar to your repair. The boiler was not shut down and given enough time to cool down. this resulted in flash steam because the boiler water was over 212 degrees when the boiler was put into an atmospheric state.

Jake

PS. if you need to replace the wet return you can do that with type K copper tubing . A lot less labor than black steel pipe.
Additionally I would look to installing the new pipe above ground using J hooks to support the tubing off the floor.

There may be some short runs of pipe that cross door ways where some of the pipe needs to be put underground. Where the tubing is put underground use clean sand to cover the tubing and install pipe sleeves where the tubing will pass thru concrete.

Jake

If the water is blue with Steamaster the PH is too low and must be raised.

What gauge tube?

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