Stainless steel tubes

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cyberbadger
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Re: Stainless steel tubes

Post by cyberbadger » Wed Oct 13, 2021 2:16 am

lostintime wrote:
Tue Oct 12, 2021 9:34 pm
The race analagy has me wondering.. I the closest place I have been able to locate that sells boiler tubing is a three hour drive, but I can get schedule pipe fairly locally. How bad of a hit would using 1" schedule 40 pipe be on heat transfer in the overall scheme of things. I intend to tig the tubes inplace regardless.
I had an ASME Code&Stamped Boiler built with 75 1.25" Tubes in 2015(200psi,30 gallons,~6HP). I would recommend to anyone making a new boiler to consider larger firetubes then 1.25", consider like at least 1.5". (I would probably go for 1.75" or 2") There was a thread on this forum where several people said a similar thing, you probably actually want firetubes bigger then you think you might want....

When you have so many firetubes it can be a big chore to clean. You're definitely going to want to clean them, it will depend somewhat on your fuel type how often.

I'll let other people chime in about the actual firetube material and thickness...

-CB
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Re: Stainless steel tubes

Post by lostintime » Thu Oct 14, 2021 2:36 am

I happen to have a 1 1/2" inch tube roller in my toolbox That has been used exactly zero times in the last eleven years, so if I go with proper tubes that will be the size, but... there was a large local project that was utilizing 1" schedule 40 black pipe and it was on a scale that they purchased it on the shipping containers quantities and they have around 400 sticks of 20' x 1" left over that is destined for the scrap dumpster next spring so, again being a miser, I ask.
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Re: Stainless steel tubes

Post by TahoeSteam » Thu Oct 14, 2021 5:46 pm

Do you know the grade of the pipe?
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Re: Stainless steel tubes

Post by lostintime » Thu Oct 14, 2021 9:57 pm

I stopped and checked, they have a pile of cutoffs 20" to 7' in length.
ASTM A53 1" sch 40 gr A F 2
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Re: Stainless steel tubes

Post by DetroiTug » Thu Oct 14, 2021 11:23 pm

lostintime wrote:
Thu Oct 14, 2021 9:57 pm
I stopped and checked, they have a pile of cutoffs 20" to 7' in length.
ASTM A53 1" sch 40 gr A F 2
Sch 40 A53 welded seam works just fine. Wall thickness within reason is irrelevant. I use SCh 40 A53 for Ofeldt watertube coils, it tolerates the winding process and holds up just fine. About six years running, keep it 100% full in the summer and drained and dry and all valves open in the winter. A firetube benefits from the pressure outside, making hoop stresses a non consideration. Steel tubes can tolerate low or no water firing, copper cannot.

Ron
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Re: Stainless steel tubes

Post by Kelly Anderson » Fri Oct 15, 2021 3:17 pm

I understand that Semple used schedule pipe in his boilers, rather than kosher boiler tube. There isn't any physical reason that they won't be successful, but the boiler wouldn't be accepted as a code or code equivalent boiler due to the "incorrect" material having been used for the tubes. By all means completely remove the coating from the outside prior to installation, and polish the ends that are to seal to the sheets if you are rolling them in. Pipe tubes may be better off being welded in so the metal isn't stretched by rolling (not sure how A-53 would stand up to that).
It was not easy to convince Allnutt. All his shop training had given him a profound prejudice against inexact work, experimental work, hit-or-miss work.
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Re: Stainless steel tubes

Post by Kelly Anderson » Fri Oct 15, 2021 3:39 pm

cyberbadger wrote:
Wed Oct 13, 2021 2:16 am
I had an ASME Code&Stamped Boiler built with 75 1.25" Tubes in 2015(200psi,30 gallons,~6HP). I would recommend to anyone making a new boiler to consider larger firetubes then 1.25", consider like at least 1.5". (I would probably go for 1.75" or 2") There was a thread on this forum where several people said a similar thing, you probably actually want firetubes bigger then you think you might want....

When you have so many firetubes it can be a big chore to clean. You're definitely going to want to clean them, it will depend somewhat on your fuel type how often.
My boiler is based on Mike Condax's tall furnace/short tube design, however, where Mike used sixty one 1.25 o.d. tubes, I used ninety one 1" o.d. tubes with retarders, and have never looked back. She has more heating surface, runs with a lower stack temperature, and makes very little smoke. The retarders make for very steady steaming.

When is is time to clean the tubes, I just reach in the stack hole, give each retarder a twist, and it augers the soot out of the tube to fall on the grate. Takes about five minutes to do the whole set.
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It was not easy to convince Allnutt. All his shop training had given him a profound prejudice against inexact work, experimental work, hit-or-miss work.
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Re: Stainless steel tubes

Post by cyberbadger » Fri Oct 15, 2021 4:18 pm

Kelly Anderson wrote:
Fri Oct 15, 2021 3:39 pm
Takes about five minutes to do the whole set.
Your mileage may vary.

It takes me 1-2 hrs and you have to watch the soot because it goes everywhere and my boiler is so tall I need a step ladder and even with the step ladder it is still extremely awkward.

In maybe 10 years I am considering commissioning a 3 pass scotch marine boiler with 1.5-2" firetubes.

If you are building a boiler it is a good idea to think about how you will actually do maintenance like brushing the firetubes.
The size of the firetubes and the dimensions of the boiler definitely factor into that.

There are somethings that may not make a lot of sense to be done on the water because things can take longer when you have an audience.

-CB
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Re: Stainless steel tubes

Post by TahoeSteam » Fri Oct 15, 2021 9:24 pm

Kelly,

your boiler and engineering spaces look very tidy and well thought-out. I like the concept of a shorter and more squat firetube with shorter tubes and larger firebox. The next best thing to a Kingdon style submerged-tube VFT.

It looks as though you could almost clamp each one of your turbulators in an electric drill chuck with some finagling and power scour lol. How close is the tolerance in your tubes between tube wall and turbulator? I like your idea of individual turbulators for the scouring process. On "George H. Sandin" we had them in rows on stainless rods to ease installation and removal. Steam lancing during the season and final brushing at the end of the season (oil fired).
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Re: Stainless steel tubes

Post by Kelly Anderson » Sat Oct 16, 2021 3:23 am

TahoeSteam wrote:
Fri Oct 15, 2021 9:24 pm
How close is the tolerance in your tubes between tube wall and turbulator?
The retarders are laser cut by a local shop and measure .050 smaller than the i.d. of the tubes. When new retarders are manually twisted. they seldom stay straight lengthwise, so when installed in the tubes they quite often scrape the tube wall on one side or the other for most of their length.
It was not easy to convince Allnutt. All his shop training had given him a profound prejudice against inexact work, experimental work, hit-or-miss work.
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