In the water injection system renovation of a certain deepwater oil production platform, a double plate API 6D check valve was selected to adapt to the special environment of platform tilting and swinging. The platform is subject to the combined action of wind, waves, and currents, resulting in continuous small oscillations. Conventional rotary check valves may experience bias due to the deviation of the valve disc center of gravity from the rotation axis, which may affect the closing sensitivity and sealing uniformity when tilted.
The double plate check valve uses two symmetrical valve flaps to rotate around the same axis, and each valve flap is equipped with an independent torsion spring. When the platform tilts, the gravity effects on the two valve flaps cancel each other out, maintaining a balanced closing action. The medium of the water injection system is treated seawater with high pressure. The valve disc and seat are made of wear-resistant and corrosion-resistant materials and finely ground to ensure effective sealing of the metal sealing pair even under low pressure difference.
The platform operator confirmed through manual pressure testing and automatic detection system that the valve can be opened and closed normally under various simulated tilt angles. After closing, the pressure is stable and there is no visible internal leakage. The API 6D standard has clear requirements for the operating torque, sealing test, and accelerated life test of check valves, and the double plate structure type is within the scope of application of the standard.
The selection of marine engineering valves requires comprehensive consideration of space constraints and dynamic working conditions. Double plate check valves are increasingly being adopted in deepwater projects due to their compact structure and balanced dynamic response. This practice has enriched the experience of selecting check valves for offshore floating facilities and expanded the application boundaries of API 6D products in special scenarios.
