Tri-clamp unit

[LukaV]

Hi all,

Does anyone of you have Tri-clamp unit calculation?

We are designing pressure vessel with Tri clamp DN300 - 12˝ cover on the top.
We are woriking with AD2000 (Europe) and i can't find anything simillar. I also checked inside ASME standard, but all i found was clamping union but the geometry of the flange is different and the connection flange to flange is metal to metal.
When i asked clamp manufactures selling clamps with specified pressure, lets say the are selling clamp High Pressure Tri-Clamp (13MHP) than the pressure is up to 150 PSI @70°F / 100 @250°F, they all reply with asnwer: Yes this clamp is designed to work under that pressure but we can not provide any certifacates for union parts (ferrule, blind, clamp).

All help welcome. Thank you in advance.

Luka

 

[LittleInch]

What sort of calculation are you after?

Looking at what you have ( any links you can share), look like vendor certified equipment tbh.

Vector techlok are the only type I see for high pressure stuff.

You're at the top end for size and pressure for these types of clamps.

Personally I think they are too easy to over tighten and repeated use or pressure cycles of the lid risks fatigue at the inner face of the clamp which no one ever looks at and they you can easily get catastrophic failure of the lid.

A rather extreme example maybe, but this https://www.eng-tips.com/threads/la...-seventeen-people-injured.484866/page-4#posts used a similar mechanism - look at page 3 for the design - and I personally thought it was a poor non fail safe design which relied 100% on the clamping force from the clamps. If that clamp itself failed then there is no back up - the items fails and the lid flies off like a berserk disk and all the contents come flying out.

Ther eis also very little to tell you its failing. If it doesn't seal all anyone does is tighten it up further...

Are you really sure you want to clamp in 150psi of pressure on a 12" lid using this type of clamp???

Has it been risk assessed / tested to failure? how will it be inspected?
Why can't you use something much more robust?

 

[LukaV]

First thank you for faste respond.

We are producing pressure vessels and normaly we go with machined flanges but this vessel is for laboratory use and the costumer wishes to go this way mostly for easy use, in worst case scenarion we will talk and try to change it to machined version.

Attached is drawing with vessel isometric view and top flange (TC) detail.

This are main working parametrs of vessel:

• Working pressure: 0-6 bar
• Test pressure: 9,4 bar
• Working temperature: 0-100 °C
• Geometrical volumen: 18L
• Working volumen: 15L
• Material 1.4404

For blind i did calculation using formulas for flat top cover and we would buy clamp with specify working pressure up to 10 bars. Here is a catch that sellers dont provie any certificats for clamping unit even if you buy ferrul, blind, gasket and clamp from them, even if they specify working pressure for clamp is 10 bar.

In the end i just wish to do calculation for ferrule that it will hold up to this pressure, mostly self check and for future vessels.

 

[LittleInch]

Thanks for the information.

My comments / advice is that I wouldn't do it using a clamp like this. There is simply too much risk, especially when the lid is being taken on and off many times, for something to break, fatigue or be installed incorrectly / worn edges, you name it.

There are many quick opening enclosures which although more expensive for sure are much lower risk.

At 6 bar, there is a force of 4.7 tonnes on the connection. I am far from surprised that no one will give you a certificate. My guess is that if you really want to do this then you're going to need FEA to show that it does or doesn't work. My biggest concern is how you ensure that the clamping force for the main bolt is controlled and not that when it leaks a bit they don't just get a bigger spanner / larger technician or don't start hitting it with a hammer. Don't tell you you've never seen technicians find all sorts of ways to add more torque to something. Hell they will probably put a power wrench on it to speed things up.

I would very strongly recommend that you choose a different way to open and close this lid on a regular basis. Remember, if it goes wrong, flies off and kills someone you're the responsible designer. Would you sit your child or partner next to it after its been opened and closed many times over say 5 years? I wouldn't be in the same room.

sorry for going on, but I really do feel that this type of clamp is simply a recipe for disaster for this use.

At the best it will start to leak and fail to seal, at worst could fail without warning.

Your call.