O-Ring seal between Pipe joints...

[amooory]

Hello,

We have a 66" O.D. Scraper launcher barrel which has an O-ring on its door. it has been noted that frequent opening and closing to the launcher's door causes a leakage from the door. The type of fluid running in the pipe is treated water.

My questions are:

1) Is there a possibility that the Metal Groove designed for the O-Ring expands causing the ring to loss it's shape?
2) Can this problem be solved using a larger ring?
3) Are there any recommendations you can help us with?


Information about the ring
O-Ring: 1630.65 MM ID, 1644.65 MM OD, 7.0 MM WD/THK, NBR 70 Shore A Hardness, -40 to 110 DEG C, Hydraulic, Pneumatic service, Nitrile Rubber, INCH, BLACK, US AS568A, RING O; Gasket; 1/4" DIA; 64-3" OD.

Ammar A. Zaatari
Plant Engineer
SWID/SWIEU
Tel: 03 877-2263
Fax: 03 877-2239

 

[jonralph]

Launcher doors are always hard to seal, especially the larger ones such as yours. How often do you replace the ring? Does it leak when a new ring is fitted? Are you using any grease? How bad is the leak? Do you not isolate the launcher for normal operation and only have it online when you are pigging?

 

[butelja]

A larger cross section O-ring will be more forgiving of surface imperfections in the mating surface. My experience with closures of the size range you mention is on pressure leaf filters. The most reliable sealing units I've dealt with use a "D" shaped ring that is roughly 0.5"x0.75". The pressure range sealed is usually 75-100 PSIG, oil service, and temperature from 100-350 °F. The closure doors have a breech lock assembly, where an outer ring is rotated by hydraulic cylinders and multiple wedges riding on lugs on the vessel and its head create the clamping load.