In the gas/oil industry, even though it has become extremely general, the use of a solid Double block and bleed valve for force energy isolation is still not adopted or applied across the board.
There are safely regulations such as engineering codes/practices and OSHA that provides us guidelines on the different types of isolation, isolation levels and where to use them. Note that each region/country or even local plants have different policies and standards.click here
Since there is a big range of actual site needs during project turnaround, execution, maintenance or shutdown, engineers involved may need to look at all choices. The industry today is sensitive on project cost, but it is remarkable not to sacrifice reliability and safety, and if possible, time and simplicity of use.
Solution with DBB valves
Compact modular Double block and bleed valve
The use of DBB control device can be categorized as a top-level isolation, second only to the real physical partition. A twin ball double block and bleed valve is a quarter-turn control device which can make a fast wall by a ninety turn which is truly a time keeping choice. Even if a gearbox is used, this is the case mainly for the bigger bore sizes, it is still just a few burns on the hand wheel. It generally has locking facilities to comply any tag-out/lock-out exercise.
Your benefits while satisfying the simplicity of intervention at the same time:
- Reduce cost
- Reduce weight
- Reduce footprint
- Reduce danger exposure
Traditional DBB arrangement
This is a conventional technique where you gather two separate ball control devices and a spool piece-in between the two valves. The bleed valve is generally retrofitted in the center spool to make a DBB arrangement. This technique takes more area, more weight and more laborious to link all the individual parts. To get the real cost, we need to factor in the individual control device testing, individual lifting, individual NDT and accessories for each part.
Other Isolation techniques
This is equal to installing a blind extension apart from the use of a display blind is more a real installment.
Designed for a simple change-over between an open spacer or a blind, whichever is needed. Just like blinding, this technique still needs a manual intervention and physical labor which uses manpower and time.
Note that for larger size and higher rating, it could be a back-breaking workout even by just turning/pivoting the plates. Similarly, the workers will still encounter the same issues like rusted bolting and the challenge of installing the gasket. Since involvement is oftentimes rare, it is extremely likely that the blind part gets rotten and may require to be cleaned and scraped before using it again.
This is also one idea of getting a right isolation where it contains a physical and actual division of the equipment or system. To break get a line break, a not fixed flanged spool part is detached from the big pipeline, and the main pipeline is blanked with blind flange. If the big pipeline has a huge nominal size, then one will have the same huge spool to discount, get rid of, and put in place in a bigger working place.