Reusability of Swagelok

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Tom McCarthy
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Reusability of Swagelok

Post by Tom McCarthy »

I’ve got some Swagelok fittings for the deuterium line. I recently dismantled one connection for the first time, and realized I probably can’t use all of it again.

It seems like the ferrules are a write-off, as they’re very hard to remove, and don’t seem to be made for re-use.

On the other hand, the nuts seem fine.. But they’re trapped on the tube. I take it I need to cut the tube to get the nuts off for reuse - unless there’s an easier way to remove the ferrules? If I could remove the ferrules, I could shorten and re-use the tube length.

See the picture shown. It’s not too long of a length of tube to lose any sleep over, but for larger lengths I’d hope there’s an alternative to grinding off the ferrules.
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Steven Sesselmann
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Re: Reusability of Swagelok

Post by Steven Sesselmann »

Tom,

Providing you don’t damage the fitting, you can reuse these several times. You need to use your better judgement when it comes to tightening. The 3/4 turn rule won’t apply.

Steven
http://www.gammaspectacular.com - Gamma Spectrometry Systems
https://www.researchgate.net/profile/Steven_Sesselmann - Various papers and patents on RG
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Bob Reite
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Re: Reusability of Swagelok

Post by Bob Reite »

I've disconnected and reconnected Swagelok fittings a couple of times. As I recall, I had to go just a bit beyond the 3/4 turns, one gets the feel for how far to tighten it.
The more reactive the materials, the more spectacular the failures.
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richnormand
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Re: Reusability of Swagelok

Post by richnormand »

I have reused these several times.

I tend to be a bit shy of the 3/4 turn at the first install since I have a RGA system and only retouch the leaky ones (if any).
That way they are in pretty good shape for several reuse, with only a mild over rotation.
You get to feel the resistance increase at the binding point.

One thing I noticed on stainless steel 1/4" pipes, in particular, is not messing with the ferrule rotation if it is slightly loose on the pipe.
On copper I only get 1 or so reuse max, none if over-tightened at the initial install.
John Myers
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Re: Reusability of Swagelok

Post by John Myers »

Ferrules aren't meant to be removed and re-crimped on a new tube. If you manged to get one of it would probable be too deformed to get back on a new tube.
At work I reuse the nuts all the time, just cut of a section of the tube and add new ferrules.
Jerry Biehler
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Re: Reusability of Swagelok

Post by Jerry Biehler »

You can buy ferrules separately and there are several compatible brands like you-lok, a-lok, and a whole bunch of others.

3/4 turns is only for 3/16" (4mm) and under. Anything bigger than that gets 1-1/4 turns.

Speaking of 3/16" swagelok, i am in need of a 3/16" to 1/8" adapter if anyone has one laying around. Darn feedthrough for my crystal monitor uses 3/16" tubing.

https://northerncal.swagelok.com/blog/b ... -and-under
ian_krase
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Re: Reusability of Swagelok

Post by ian_krase »

Swagelok connections are definitely re-makeable at least a few times, but opinions of their reliability vary. I have had good luck re-making swagelok connections several times on my vacuum system -- these were brass-and-copper swagelok, not stainless.

I suspect I was crimping the connection slightly further each time, not really a long term plan.


You definitely can't strip the ferrules off of tubing and have them be re-usable though. Fortunately, the ferrules are cheap and can be bought in either brass (for copper tube) or stainless in packs of 10.


Nuts and bodies are definitely reusable indefinitely.


Note that the ferrules bite into the tubing pretty deep when properly tightened. You won't be able to cut them off without scarring the tube -- and it will have a necked-down shape to it.
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Re: Reusability of Swagelok

Post by Tom McCarthy »

Sounds good, thanks guys.
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Re: Reusability of Swagelok

Post by prestonbarrows »

Swagelok ferrules are only meant for 1-3 uses for near-STP contditions. Swagelok ferrules are garbage for high quality vacuum. Throw them out.

Luckily, Swageloc VCR connections are specifically made for the type of vacuum connections fusors use. There are countless VCR fittings available as stock/surplus on ebay or other vendors.

In short, 'swagelok ferrules' that crimp radially onto the working tube in a permanent fashion, are garbage. Swageloc VCR fittings that crimp axially into a permanent gland are golden for all time plus a 5 cent replacement fee.
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Richard Hull
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Re: Reusability of Swagelok

Post by Richard Hull »

I will not argue against VCR fittings for they are golden as is their price. If one is looking to readily hit 10 e-6 torr or hold it for long periods, then fine.
However the standard old swageloc ferrule fittings are fine for any and all fusor work at the amateur level and are a tiny fraction of the VCR fitting's cost.

If your life revolves around taking apart gas connections in a large vacuum gas system with great regularity for some, God knows what possible reason, then you need VCR fittings all the way.

I have used only 4 old cheap ferrule swageloc fittings in my entire fusor IV system since 2004 and never had to loosen, tighten or take apart a single one since 1984. One doesn't "play" with a fusor gas system! You put it together and walk away.

You do not purchase a bunch of used swageloc piping as part of an old surplus system and reuse the fittings. You cut the fittings off and get new ferrules and female fittings if you feel you must use the old piping.

Now, if your pockets are bulging with VCR money, go for it.

Richard Hull
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ian_krase
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Re: Reusability of Swagelok

Post by ian_krase »

Yeah, brand new brass swagelock works fine and fairly new brass swagelock is OK. I wouldn't subject it to vibration or too much thermal cycling though.

Plus there are fully compatible and just as good swagelock imitations commonly available from McMaster or even Amazon at much lower prices. Especially when made of brass, for combination with 50 cents a foot hand bendable copper tubing from local hardware store.

You can also use o-rings and backwards ferrules to turn swagelock into poor man's ultratorr fittings. This would function as the dismountable tube fitting we need. This or VCO fittings are preferable if high temperature or UHV is not needed.

It may be possible to pick up large "garbage" assemblies of VCR from semiconductor business surplus and cut them up.
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Re: Reusability of Swagelok

Post by Jerry Biehler »

VCO fittings are not used for high temp or high vacuum.

Swagelok new or old is fine for high vibration no matter what material you use. Brass is cheap and stainless is corrosion resistant. There are also steel and aluminum versions out there plus a couple exotic metals.

I have reused a lot of VCR stuff, just did on the gas manifold on my big system. The big thing about VCR is you are going to need a orbital welder ideally or at least a tig machine to weld the fittings on, there is no simple way to make new assemblies with VCR.
ian_krase
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Re: Reusability of Swagelok

Post by ian_krase »

Why not silver brazing?
Jerry Biehler
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Re: Reusability of Swagelok

Post by Jerry Biehler »

Silver brazing is fine as long as you are sure you have cadmium free rod. The problem is the internals can be very dirty and oxidized and it is going to be a real pain to clean it up. So for larger stuff it is fine or for stuff like water cooling lines inside the chamber. It is also used for connecting chunks of copper together since it takes a heck of a lot to tig weld copper, especially big chunks.
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Re: Reusability of Swagelok

Post by prestonbarrows »

Standard "Swagelok" fittings (the crimp ferrules) are really only meant for one or two uses with every day fluids like, say, a refrigerator condensor. They can be pressed into use for vacuum, but expect to hit problems if retightened more then once or twice. Maximum performance in the 1E-5 ish Torr range.
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Swagelok the company also makes so called VCR fittings which are actually designed for vacuum service using a metal-to-metal seal by compressing a disposable copper gasket between stainless flanges. The gasket is fully disposable/replaceble and costs about 5 cents. These fittings will outperform any pump the amatuer is likely to use. They cost about the same as standard 'swagelok' fittings. They can be purchased directly through your local swagelok dealer or secondhand through ebay. One drawback is they are more likely to require brazing/soldering but this can easily be done with a $5 homedepot propane torch and silver brazing rod.
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If you are brazing, shock cooling with water is a good method to break up the flux residue. A simple wire brush works in a pinch. Sandblasting is usually the best solution. Really, you only care about cleaning the vacuum facing side. The hard to reach bits will be inside the water channel and not enough to be a concern for amatuer fusors.
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