In the Oil/Gas industry, although it has become very common, the use of a compact Double Block & Bleed (DBB) valve for pressure energy isolation is still not applied or adopted across the board. I have experienced a few times wherein the use of a DBB valve for process isolation is more of an option rather than a design requirement.
Double block and bleed valve systems are conventional installations for most End-Users in the Oil and Gas industry. Conventional installations of DBB valve systems have become a normal practice and can even be found on offshore platforms.
The installation of DBB valve systems is a time consuming process that can negatively impact employees and their work production. The normal process of this type is baded on:
Using two 6” 1500 class ball valve with all the additional materials,
Long and comlex installation process (up to a 41 steps)
Huge amount of material (weight of 2,645 lb(s) = 1200 kg
I often hear people saying “Metal seated valves with graphite sealing don’t need to be fire safe tested, as all the components are fire resistant”.
To be honest, starting my career as a valve engineer, I was convinced, that this common understanding is true – until I did fire safe tests on my own for our Monoflange Series, many years ago. Even after this long period of time I remember very well, when we did the pre-tests. I looked very surprised, when the valve seat was leaking during the firing of the valve.
Reliable fire protection is essential for industrial valves in industries with sensitive applications. Because of the dangers that come within installations in the oil and gas, chemical, and petrochemical industries, the valves used must guarantee a reliable and safe shut-off in case of fire.
Juan is a Sr. Consultant with over 25 years of experience in the upstream O&G Industry working at different levels and capacities from Lead Engineer to Management, holding a successful record of accomplishments. Experienced in Advance Drilling, Production, and Marine Systems and have participated extensively in Rig (JU & Floaters) Design and Construction, with In-Depth involvement from Concept Development to Commissioning and Delivery of over 20 new Offshore Rigs, in addition to several life enhancement, upgrades, and refurbishment projects.
The higher the pressure, the more the sealing elements are pressed together – and the higher are the forces on the ball and the seat.
This would not be a big problem, if the valve has not to be operated like a check valve. But a ball valve has to be operable, even under high differential pressure.
When high forces are acting on the sealing elements, the friction between them is high. This means that the operation torque and the wear on the parts are also high.
