Flex pipe

A special section just for steam engines and boilers, as without these you may as well fit a sail.
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Lopez Mike
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Flex pipe

Post by Lopez Mike » Sat Sep 09, 2017 2:20 pm

I have been using ordinary 5/8" copper pipe with flare fittings for my steam pipe from the boiler to the engine for some years now. After three to four years I see a small wisp of steam and find a small crack running around the pipe right at the base of the flare. It doesn't fail catastrophically and I have just been replacing the whole 18" pipe when this happens. The steam pipe has a gentle right angle bend in it to absorb relative movement during operation but clearly the vibration stress is concentrated right at this point.

I have thought of annealing the pipe end after flaring. Another fix would be to use a braided flexible hose with schedule 80 steel pipe to make up the needed distance.

I see these S.S. flexible pipes sold for connecting domestic hot water heaters. https://www.amazon.com/dp/B00662MIN8/re ... B005O19OTS

I wonder if they would stand up and, more importantly, if they would fail gracefully rather than just breaking suddenly? I think they are available in copper as well.

Thoughts?
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Mike Rometer
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Re: Flex pipe

Post by Mike Rometer » Sat Sep 09, 2017 3:40 pm

Obviously fatiguing at the most rigid point. Perhaps remove the pipe at each lay up, and re-anneal it each time before re-fitting? Having said that an 18" length of copper isn't that expensive to replace anyway, just a pain to have to bend up again.
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Re: Flex pipe

Post by cyberbadger » Sat Sep 09, 2017 5:29 pm

This says up to 450 degrees F and 450PSI - sounds ok for steam...

I even got your solder ends for 5/8 and the material is bronze.

Vibration-Resistant Water Hose with Solder-Connect 5/8 Copper Tube Fittings
Bronze
$29
https://www.mcmaster.com/#5611k27/=19b6yap

However - maybe this is a time to count your blessings so far and try to upgrade and replace some of that copper pipe with some steel....

-CB

P.S. I really like and use long section of steam rated braided SS from mcmaster. My big grip is that it does change the exhaust sound with the ribbed interior. Otherwise it's bomber.

-CB
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Lopez Mike
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Re: Flex pipe

Post by Lopez Mike » Sat Sep 09, 2017 6:29 pm

That's a nice looking flex hose from McMaster-Carr though I would probably go for pipe fittings on the ends as my intention is to go for schedule 80 for the rest of the run. Any link for that braided hose you are using now?

Yes, just replacing the copper pipe more often would be less trouble and perhaps annealing once in a while would help. I have hopes of doing a more pleasing job of insulating the steam pipe so not disturbing it would be a good thing.
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Re: Flex pipe

Post by cyberbadger » Sat Sep 09, 2017 7:32 pm

The have a few options...

316 Stainless all the way - or a cheaper 321 Stainless Steel Hose with 304 Stainless Steel Ends. I use the second.

You can get male/female male/male female/female npt ends.

The have an extra-flexible option as well. I helped get a Canadian steamer get a hose with this option because the plant was packaged together tightly and he needed more give to complete the connection. McMaster won't ship to Canada.

For my own purposes I try go one up in size so that the hoses are not a bottleneck, but that may be unnecessary. (So I get 3/4 NPT where I want 1/2)

BTW I'm happy to buy and ship any mcmaster carr parts for Canadians or other international steamboaters that they won't sell to if I am reimbursed the cost.

https://www.mcmaster.com/#braided-stain ... e/=19b8gkq

-CB
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Re: Flex pipe

Post by Wayleon » Sun Sep 10, 2017 3:30 am

I use a braided extreme temperature hose on the Chester D. between the boiler and the engine. I want to put as little stress on my boiler and engine fittings as possible as I bounce down the road.

https://www.mcmaster.com/#54875k13/=19beo6v
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Re: Flex pipe

Post by Lopez Mike » Sun Sep 10, 2017 5:16 am

That looks like the way I'll go. Probably the 54875K15 with 1/2" I.D. for my application. I need a 90 degree bend and a 12" length will keep the radius well within their stated limit. Thanks.

When I put my power plant together I used a lot of schedule 80 steel fittings but they are showing some surface corrosion after several years of drips and heat. Rather than paint them I think I'll spring for bronze. Now to do some more looking through that online catalog for them. My local hardware store starts laughing when I come through the door and the old time marine hardware store a ferry boat ride away is going out of business.

I use hydraulic couplings for my unions with great results but, again, I tried to control costs by using cad plated ones and I will probably bite the bullet and replace them with S.S. ones.

One of the entertaining things has been that photographers have complained about me stopping the various steam leaks like valve packings as they say it takes away the 'romance' of the photo. They don't have to top off the hot well! I placate them on startup by opening the cylinder cocks for a short time. Great noises for them as well.

It also fascinates bystanders to have the engine ticking over while tied to the dock. The combination of the various monkey motions as well as water gurgling out the stern transfixes them. A polished prop helps too.
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Re: Flex pipe

Post by barts » Sun Sep 10, 2017 9:46 pm

Lopez Mike wrote:That looks like the way I'll go. Probably the 54875K15 with 1/2" I.D. for my application. I need a 90 degree bend and a 12" length will keep the radius well within their stated limit. Thanks.

When I put my power plant together I used a lot of schedule 80 steel fittings but they are showing some surface corrosion after several years of drips and heat. Rather than paint them I think I'll spring for bronze. Now to do some more looking through that online catalog for them.
Why not paint those fittings? There are paints that will easily handle the temps, and a bit of phosphoric acid prep before painting will make sure the paint sticks.

- Bart
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Bart Smaalders http://smaalders.net/barts Lopez Island, WA
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Lopez Mike
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Re: Flex pipe

Post by Lopez Mike » Mon Sep 11, 2017 12:36 am

I've had some success with paint, Even just barbecue black. But it's a bit much to ask paint to withstand a wrench and I do disturb several of these unions regularly. In fact, every time I trailer the boat at least three of them are disconnected.

Perhaps if my trailer was suspended a bit better than a hangman's cart I wouldn't need to unbolt everything lest it depart on the highway.

Keeping a launch in operation is bit like Zeno's Paradox wherein you travel half of the way in a given period of time and then half of the remaining distance in a subsequent equal period and so on. Thus you can never arrive. Just approach a goal such as reliability. I'm down to something acting up perhaps once a season which nothing to sneeze at! Always something new and different to fuss with.
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Re: Flex pipe

Post by cyberbadger » Mon Sep 11, 2017 2:40 am

Lopez Mike wrote:Keeping a launch in operation is bit like Zeno's Paradox wherein you travel half of the way in a given period of time and then half of the remaining distance in a subsequent equal period and so on. Thus you can never arrive. Just approach a goal such as reliability. I'm down to something acting up perhaps once a season which nothing to sneeze at! Always something new and different to fuss with.
Whatever do you mean? :roll: :lol: :twisted: ;)

John Winn this season had an outing where a wrench/spanner was not used! That's impressive.

I think there is always something. It's just different for everyone. And just when you think you get it "fixed" it throws you a curve ball. This summer has been very successful in terms of never needing a tow for Nyitra. I'm sure having said that next time I will need a tow. I was looking at my batting average in this regard. I think I'm at 9/10 steamings not requiring a tow, this is including her maiden voyage.

For me the electric pump for initial water fill has been a PITA. The HTD pulley and gates powergrip 50mm has been awesome. Even a prop strike only caused some wear. The slip Nyitra is in is too shallow right now, so her 1st rudder has been beaten on the rocky bottom into compliance. :o :shock:

-CB
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