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Piping, Valves and Actuator Offshore Coating Case Studies
Published in Karan Sotoodeh, Coating Application for Piping, Valves and Actuators in Offshore Oil and Gas Industry, 2023
A valve’s top flange or mounting flange is a flange on the top of a valve that allows the attachment of the valve to the valve actuator or gearbox. The valve top flange can also act as a support for connected components such as a gearbox or actuator according to the API 6DX standard for actuator sizing and mounting kits for pipeline valves. The mounting flange is typically enclosed with the connected component, so it is not exposed to the corrosive environment in general. However, the gearbox or actuator could be disassembled from the valve for maintenance and repair. In that case, the valve top flange would be exposed to the corrosive offshore environment. A practice experienced in some offshore projects is to apply at least one layer of epoxy primer to the uncoated areas of the top flange in carbon steel material for corrosion protection. Figure 6.24 illustrates the top flange of a ball valve in carbon steel material. The ball valve, including the outer area of the top flange, is coated with TSA. The inner area of the top flange is coated with one-layer epoxy primer in red color for corrosion protection.
Controls
Published in Samuel C. Sugarman, HVAC Fundamentals, 2020
Amplifying or Retarding Relay: Changes the output start point. It is also know as a bias start relay or ratio relay. A typical application is when a retarding relay is installed to eliminate the simultaneous heating and cooling that occurs when a heating valve and cooling valve are operating from the same controller and have an overlapping spring range. Example: A normally open heating valve has a spring range of 3 to 7 psi. The normally closed cooling valve’s spring range is 7 to 11 psi. A retarding relay is installed between the valves. The sequence is for the output pressure from the thermostat to go to the heating valve actuator and then to the relay. The relay then sends a signal to the cooling valve actuator. If the thermostat output pressure is 7 psi, the heating valve actuator senses 7 psi, as does the input to the relay. If this relay is set for a 2 psi retard bias, the input to the relay is 7 psi, but the output of the relay to the cooling valve actuator is 5 psi. Therefore, the cooling valve would not start to open until the output from the thermostat was 9 psi (the cooling valve gets 7 psi).
Power Cylinders and Control Drives
Published in Douglas O. J. deSá, Instrumentation Fundamentals for Process Control, 2019
The valve speed required may not be matched exactly because gear ratios give output shaft speeds that are in “steps.” The operating speed will vary slightly while the valve is under load, which is normal with all “cage” motor drives. Doubling the speed of an actuator for a given torque requires the motor horsepower to be doubled also. Hence, to avoid this situation and yet achieve nearly the same results, the “lead” of the screw is doubled instead. This has the effect of keeping the motor rpm the same, but increases the torque and horsepower by only a small amount. If the valve actuator is to be self-locking, that is, if the valve is to remain in its last operating position with no signal applied, the stem thread or quarter-turn gear box must be irreversible. Figure 17.8 is based on the experience gained by Rotork over the years and shows the maximum thread lead that may be used with a given stem diameter to prevent “overhauling” occurring in the gearing, i.e., keeping the gearing from being driven backward by the reverse thrust from the valve.
Experimental analysis of the volumetric and thermal efficiency performance of a novel direct piezo-acting CVVT mechanism
Published in International Journal of Green Energy, 2023
A. Sürmen, M.I Karamangil, A Avcı, B. Dirim, F. Işıklı, M. Tekin, N. Türköz
In electro-hydraulic valve actuation systems, the high-pressure fluid in the hydraulic actuator provides the necessary power for valve movement (Chen et al. 2018; Li et al. 2017; Li, Khajepour, and Devaud 2018; Pournazeri, Khajepour, and Huang 2018). Power output above 10% was obtained in the studies. Similar to electromagnetic valve systems, a closed-circuit electronic control is required to adjust the valve seating velocity, transition time, and reduce cyclic variability (Anderson, Tsu-Chin, and Levin 1998). In addition, servo-valve response time is one of the important problems of this variable valve timing system. Electro-hydraulic and electropneumatic valve actuation mechanisms are similar to each other in terms of working principle. The difference between them is that while high-pressure hydraulics are used in hydraulic systems; compressed air is used in other systems (Taşlıyol 2011).