Why insulating gasket often damaged?

[ourengtips]

In my company, in Vietnam. We using Cathodic protection system to prevent corrosion for buried pipe line. Its length is 7km, diameter of 14".
We use insulating gasket, and its specification like this:
Type E Full Face gaskets
Dielectric strength: 500V/Mil
Compressive strength: 25000 PSI
Materials: Neoprene faced phenolic/ plain phenolic
Tmax for cont. use: +110 0C
Tmin for cont. use: -55 0C
Water absorption: 1.6% (3mm thick)
Nitride seal element
- Insulating sleeve (Full length)
Materials: Mylar.
Dielectric strength: 4000V/Mil
Tmax (operating): 150 0C
Water absorption: 0.8%
Wall thickness: 0.8mm
- Insulating washers
Materials: reinforced phenolic/ high
strength class clad phenolic
Tmax (operating): 150 0C
- Steel washers: 3.2 mm thick plated
hot rolled steel
And we use spark gap, its specification:
- DEHN
Threshold a.c. voltage 50 hz - 1.0 KV
Threshold surge voltage (1.2/50) - 2.2 KV.
Rated discharge surge current (8/20) - 100KA.
Explosion protection - Special type of protection "s" acc. To VDE 0171/49
Ignition group - G4 Electrode material - tungsten/copper
Cable length : 100ml/200ml
Angled Connection Bracket : d1= max.60mm

Result: The insulating gasket is often damaged (1 year a time, it is shorter then its life as the purchase told me ) like the attached pictures (please see the pictures). The insulating gasket often have a hole below the inner diameter.

Would you please give me an advice?. I need your help!
Best regards!!!

 

[BigInch]

too close. Back up and take another picture.

**********************
"The problem isn't working out the equation,
its finding the answer to the real question." BigInch

http://virtualpipeline.spaces.live.com/

 

[rneill]

You didn't mention the Flange Class ?

If you want to step up to something that is stronger, you could consider the Pikotek PGE or PSI Linebacker gaskets. If you really want to get something that is very strong (but also very expensive) you might consider the Pikotek VCS or the PSI Lineseal gaskets.

 

[ourengtips]

Hello BigInch, meil!
Thank you for your reply!
I attach one more picture, further then the first one. Please have a look!
And i give more information about our Cathodic protection system's specification. (Please see the attached specification document).
The operating pressure is 22.5 bargs (class 300).
It always has a hole below the inner diameter and has some dirty fluid like gasoline.
Could you please give me some recommendation!
Thank you!
Best regards!

 

[ourengtips]

Another picture, further than the first one.
Thank you!

 

[rneill]

I would buy a Pikotek PGE gasket myself. It is more money but you won't have problems.

 

[BigInch]

Given that the whole gasket looks like its cut off-center, its probably just another manufacturing quality issue, or it happened during installation.

**********************
"The problem isn't working out the equation,
its finding the answer to the real question." BigInch

http://virtualpipeline.spaces.live.com/