Hydrocarbon Drains & Vents Design
Hydrocarbon Drains & Vents Design
(OP)
In our plant all drains or vents, which are attached hydrocarbon lines, discharging to the atmosphere have an isolation valve with:
1) plug ,or
2) blind
The insurance company inspector is asking for double isolation valves for these drains and vents.
1) Is double isolation valves requirement is part of the industry codes???
2) Do not you think that a plug or blind should do a similar job like a second isolation valve???
Thanks for participation.
Thanks for your participation
1) plug ,or
2) blind
The insurance company inspector is asking for double isolation valves for these drains and vents.
1) Is double isolation valves requirement is part of the industry codes???
2) Do not you think that a plug or blind should do a similar job like a second isolation valve???
Thanks for participation.
Thanks for your participation





RE: Hydrocarbon Drains & Vents Design
In your case, you need to evaluate whether drains and vents under scrutiny are regular process vents or not. Sometimes hydrotest vents are left in the piping system with blinds or plugs and never be used in the regular operation. If it is a regular process vent or drain, assessment has to be made based on the piping pressure rating/operating pressure.
RE: Hydrocarbon Drains & Vents Design
For 1" or less, a single valve is enough, ended with a thread and a plug. If the drain or vent is unfrequently used, it is very advisable to tack weld the plug. For pipe that can be exposed to vibrations, the use of goosets is also recommended. Some refineries use goosets for all purges and vents, with or without vibrations.
If the purge or vent is being used frequently, like in start ups or shutdowns, you must judge, for each case, the convenience of a second valve.
For purges and vents larger than 1", moderate to high pressures (let's say more than 10 psig) a double block is preferable.
Have a safe day
J. Alvarez
RE: Hydrocarbon Drains & Vents Design
The site's practice is to prefer double valves from an operating point of view but they will accept a flange or plug on some applications where operation is infrequent. The main concern I have with relying on plugs or flanges is ensuring they are reinstalled after use. It's easier to close a second valve than reinstall a flange (with a new gasket of course), find where you've put the plug, etc.
One previous plant I worked at used threaded caps on all drains and attached them to the piping with a short chain so they couldn't be misplaced.
RE: Hydrocarbon Drains & Vents Design
In mentioning site practices, last year I was on a start-up team for a new plant where only flanged valves were used for vents and drains. At first it seemed like it would be hard to live without the 3/4" threaded (and plugged) valves I have been used to. As there are only 4 bolts to a small flanged valve, I actually found it to be not at all inconvenient and I feel sure the integrity is much better in many services once the long term effects of corrosion are considered.
RE: Hydrocarbon Drains & Vents Design
at the plants I've worked and also at the one I still work each shift has it own section of the plant. This includes the staff.
This shift/group is responsible for housekeeping, blinds & plugs, etc.
The first responsability is for the operator who uses the drains/vents. After this it's the responsability from the team to which this area is assigned to, to make sure they're in place after usage.
Grtz
Ben
RE: Hydrocarbon Drains & Vents Design
Some info for you on vent and drains.
I completed a startup a few years ago. Our site is close to the local community so we cannot afford any environtental spills or risk fines or shutdowns to prevent us running while investigation - so we are very caucious. On all the plants startup plans we have a vent and drain check list so before we start up we had a documented record to know we'd checked everything. At the time I throught it was a bit excessive but we did't have one spill from an open vent or drain.
The check list if well organsed (ie by floor level) etc does take long even on a big plant.
RE: Hydrocarbon Drains & Vents Design
For some reason, the safety department and insurance company did not like the more common term of "dead man" handle. Maybe it was a sexist term?
If the insurance company requires it as a matter of coverage, then just accept it. quarter turn valves in particular have a poor track record of accidental opening due to someone walking by and brushing it open or getting it caught on a coat sleeve, etc.
RE: Hydrocarbon Drains & Vents Design
Hope this helps.
saxon
RE: Hydrocarbon Drains & Vents Design