O-ring sealing problem 2

[vahabsolgi]

Hi every body
I want to seal an electrode which is installed into a hole with an viton material O-ring. The o-ring size is 3mm as inner diameter and 1.5mm as thickness. The operation pressure is 30bar and the maximum temperature will be 120 degree centigrade. the o-ring is 0.6mm compressed after installation. Other dimensions have been mentioned in the attached link.
After assembling this setup it is noticed that there is a leakage even in lower pressures (10 bar) in the place of sealing o-ring.
I would like to help me and tell me where is the mistake and how should I change the design to overcome this problem.
Moreover is there a standard maximum pressure range which small o-rings can seal?

 

[hydtools]

It appears that the electrode retaining structure may be very flexible in the area of the electrodes. Is there outward displacement when the electrodes are at pressure allowing the electrodes to move allowing the orings to leak?

Ted

 

[desertfox]

Hi vahabsolgi

Can you change the sealing arrangement so that the ‘o’ ring seals on the radial parts of the electrode and internal bore of the vessel see sketch. Sealing as shown means the bolts don’t need to compress the seal, the bolts merely stop the parts falling out. It might mean though you need a bigger size ‘o’ring to do this.

{img

https://res.cloudinary.com/engineer...75E22D-36F6-41FF-91D5-E50F1602BBD5_gxgths.jpg

]

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[vahabsolgi]

Deasert fox
the bolts are been fastened very tightly by hand.
there is not enough room to change the o-ring arrangmnet to seal radially.

 

[vahabsolgi]

hydtools
if there was any displacement it will be very small and there is no way to measure it but I think this is not our issue because the plates are very solid

 

[desertfox]

Hi vahabsolgi

I suspect that you cannot tighten the bolts hard enough, those seals will take a lot of force, also even though you cant see any plate deformation it might still be happening and you are losing compression load. try googling the load to compress an 'o'ring and you will see what I mean, what size of bolts are you using and can we have some dimensions of the bolt centres, the more info youcan give in a single post the more we might help

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[hydtools]

Material hardness is generally chosen to be soft enough to compress and hard enough to prevent extrusion. In this case with little chance for extrusion, a softer oring will work. It will be easier to compress and conform to irregularities.

Ted

 

[vahabsolgi]

Hi All
I was Checking the Sealing system practically and I realized that the problem is not from the electrode. The leakage come from the other part of the assembly.
Please take a look at the attached drawing. I let the pressurized air flow into the tube and the checked every point of the system by soap bubbles. It came out that the leakage occurs mostly right after the pass in which the "flange B Sealant" and "O-ring (b)" are supposed to seal there.
some of the dimensions and sealing properties have been mentioned in the drawing.
the questions is that why the o-rings and the flange Sealant (b) can not seal the system.
meanwhile the pressure I ran the test was 15 bar and also the flatness of the seal contacting surfaces is visually excellent.

 

[desertfox]

Hi vahabsolgi

It looks to me at flange B You are pressing the o’ring and flange seal against each other, can you either blow the drawing up in that area or confirm my thoughts thanks.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[vahabsolgi]

Hi Desertfox
the Flange seal ant the o-ring are not being pressed against each other. as it's shown in the attachment both flange seal and the o-ring b are being pressed to a solid steel part.

 

[hydtools]

Which seal is leaking? Face seal or diametral oring.

Ted

 

[vahabsolgi]

Hi Hydtools
I do not have any Idea. I can only check both seals together. the leakage can be from either of them!

 

[hydtools]

Let us assume the oring seal does not leak.

Create a circular textured face for the flat gasket to seal against instead of a smooth face. Do this to create hills and valleys in a circular pattern across the flat faces. Test.

Ted

 

[vahabsolgi]

Ted
About your previous question both face seal and diametral one are leaking because the pressure pass through the flange seal and then through the o-ring where the bubbles are visible there so no one of the seals are doing well! Why is that for!?
Anyway great suggestion, I will create a circular textured face for the flat gasket and let you know the results. but was wondering if there is any rule or general principle which I should consider in design such gaskets.

 

[hydtools]

If the gasket seal arrangement works, the oring seals would be redundant.

Ted