Developing hydraulic quick couplings for shallow, deep and ultra-deep offshore oil and gas applications presents a unique set of challenges. Seal packages, water depth, separation force and material selection are among the many elements that must be considered to create a reliable and secure connection.
In this post Jason Mikulski, business development manager for Parker’s Quick Coupling Division, addresses some common questions or concerns that often arise early in the selection process.
I want to connect the coupling with 10,000 psi of internal pressure at 3,000 m but will disconnect topside at 0 psi. What type of seals do I need? What product can meet these requirements?
Since the internal pressure will exceed the external pressure (3000M = 4388psi) by over 5000 psi, the valve seals will be subjected to high velocity flow during connection. This will require them to be made of a robust thermoplastic such as PEEK and be well secured to the valves.
Most of the products in Parker’s subsea catalog have this type of valve seal and can handle connection under pressure. In regards to the interface seal, since you’re disconnecting topside at 0 psi you can use a coupling with a simple back-up/O-ring/back-up sealing arrangement and proper valve timing. Parker’s DSE series has the PEEK valve seal, the back-up/O-ring/back-up interface seal and proper valve timing, and is also very cost effective.
I have read about low separation force subsea couplings. How much lower is the separation force than a traditional subsea coupling?
A low separation force coupling reduces the force by up to 55%. For example, if you are using a ½” DSC style traditional coupling, your separation force is 695 lb/1000psi. If you were to use a ½” DSL low separation force coupling the force would be 307 lb/1000psi.
Changing from a DSC to a DSL would also increase your Cv value from 2 to 3. This is an added benefit of using some of the latest coupling technology on the market.
I’ve determined my application only requires a coupling made from 316 stainless. Can I use a 316 non-spill coupling from your standard coupling catalog for a subsea application?
Couplings that were not originally intended for subsea use can be used subsea under the right conditions. The primary concern is typically that the external pressure cannot exceed the internal pressure by more than 500psi. This is due to the fact that the seal package was designed to work when the internal pressure is higher than the external pressure.
Connecting and disconnecting under pressure, life expectancy and other factors must also be taken into account. When applying couplings that were not originally intended for subsea use it is best to contact the Parker Quick Coupling Division to discuss your specific application.
Article contributed by Jason Mikulski, business development manager for Parker’s Quick Coupling Division
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