KOSO Kent Introl Further Extends its Range of High Pressure Subsea Choke Valves

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12 March 2020

As part of a recent prestigious order for a Far Eastern client, KOSO Kent Introl has further developed its range of API 6A 15K Subsea chokes for a Subsea Capping Stack System. This follows on from our 2018 announcement of supplying an API 6A 15,000 PSI choke for a specialist Subsea System. The previous Subsea Choke was an API 6A 15K product that was designed and manufactured to handle 800 bar pressure drop under normal operating conditions. However, for this Capping Stack application the pressure drop requirements were even more extreme. All four subsea chokes had to accommodate an Inlet pressure of 1035 barg with an outlet pressure of 20 barg.

To handle the 1015 bar pressure drop, our proprietary solid Tungsten Carbide Vector (Velocity Control) trim was selected. The choke trim was specially characterised so that under low flow opening and extreme pressure drop conditions, there were 10 discrete stages of Velocity and Pressure control.

A full Computational Fluid Dynamics (CFD) erosion analysis of the subsea choke trim design was undertaken, and the design of the choke trim was "fine-tuned” to ensure that the optimum solution was supplied.

During the CFD Analysis, it became apparent very early on that a single stage trim design would have experienced severe cavitation and would not have been suitable for this application.