The DBB-SAVER is used to 100% mitigate any leakage through either a Double Block & Bleed or Single Isolation valve configuration (e.g. ball, gate or plug valve). Thereby, it is despite leaking isolation valves able to combine the two main objectives the industry is striving for:
- maximum safety for the workers, in combination with
- maximum commercial availability of the installation
When maintenance has to be performed on a part of the installation, whilst the remaining plant remains pressurized and operational, the to be maintained equipment has to be safely isolated from the remaining plant.
This is done by closing isolation valves, often Double Block & Bleed (DBB) or Single Valve (SV) configurations. In some occasions followed by the installation of a blind flange. But: often valves are leaking, which makes safe performance of the maintenance work (or safe installment of blind flanges) hazardous and therefore not allowed.
When valves are leaking beyond the acceptable leak rate, and repair is not practically possible, what are then your options?:
- Closing a valve upstream of the leaking valve and depressurize the part in between?
This will have commercial consequences, as there is often more equipment that is to be taken out of operation, sometimes even leading to a total plant shutdown
- Postponing the maintenance
This leads to high cost, reduced plant availability, cancelled maintenance crew reservations etc.
- Injecting grease (if possible)
In case there are grease or emergency sealant nipples, these can be used. However: grease will disappear and causes a sudden, non predictable gas blow-through. The tightness of the valve is usually monitored periodically (e.g. 2x per operator shift), so workers could be exposed to hazardous gas for a prolongued period of time. Besides, dirt is sticking to the grease on the sealing surfaces and will cause even more severe leakage in the future
- Inject sealant (if possible).
In case sealant, the valve is often not fit for purpose anymore afterwards, and will have inline leakage when the valve is taken back in operation
- “Accept” the leakage, and take additional measures on the work place to minimize the hazard
e.g. by gas detection, using explosion safe tools or workers wearing personal protection equipment. The problem of these measures is, that they all are last line of defense measures, and dependency on those should be avoided
None of the above options is ideal. There is constantly a trade off between safety and commercial objectieve.
But, with the DBB-SAVER, you can combine both safety and commercial objectives.
With the DBB-SAVER, all above issues are solved:
- Remaining plant stays operational
- Continue with the work as planned. No risk of delays due to leaking valves
- No greasing, no risk on sudden gas blow-through
- No sealant necessary, the valve stays fit for purpose afterwards
- No dependency on last line of defense PPE.
The application of the DBB-SAVER surpasses the safety level of a conventional bleed by far.
It is the best solution available to deal with your leaking valves.