2 replies to this topic

[rowanlim]

Hey all I'm currently involved in P&ID review, I've a question: what's the difference between a seal trap & a deck gully? The only difference I see (from the P&ID) is that the seal trap has a cap which is absent in the deck gully design. Is there a difference in function for both items? I tried to find information online but there's not much elaboration (or I'm looking at the wrong place).

I'd appreciate any feedback, thanks!

[ankur2061]

Rowanlim,

A gully is a drain channel which could be with a liquid seal or without a liquid seal depending on whether the drain system is categorized as hazardous or non-hazardous. For drains classified as hazardous a liquid seal is mandatory to prevent hazardous volatile hydrocarbon gases to migrate to areas classified as non-hazardous.

The term "deck gully" is specifically used for offshore platform drainage system. The term "deck" means the deck of an offshore platform.

"Seal trap" is basically a vessel or pipe expansion with a liquid seal to cater for sudden large volumes of drainage encountered and which could also encounter drains from hazardous areas.

I had prepared an "Drain System" standard for a middle east offshore company during my tenure in the middle east. The appendices of the standard had many figures and sketches related to seal pot, U-siphons and gulleys.

I am attaching those sketches for the benefit of all those who would like to understand what drain gulleys, seal pots and drain siphons are and specifically for offshore platforms.

Hope this helps.

Regards,
Ankur.

Attached Files

•  Seal_Pot_and_Gulley.doc   113.5KB   29 downloads

[rowanlim]

Thanks Ankur, the attached file helped me to understand what a gully is!