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Valve and Actuator Technology for the Offshore Industry
Published in Karan Sotoodeh, Coating Application for Piping, Valves and Actuators in Offshore Oil and Gas Industry, 2023
PSVs, as the name implies, have a safety function. The main aim is to install this type of valve on overpressure equipment or piping to prevent overpressure scenarios in the plant. PSVs release overpressure gasses from equipment in order to avoid overpressurizing and potential process safety incidents and to protect human life, property and the environment. An overpressure scenario refers to a condition that would cause a pressure increase in the piping or pressure equipment beyond the specific design pressure or maximum allowable working pressure. A PSV is considered the last line of defense for overpressure prevention. This means that other overpressure safety devices, such as emergency shutdown valves, should prevent overpressure scenarios before any requirement for a safety valve to act. Figure 5.59 illustrates a PSV inside a power plant; its spring is visible in the picture.
Design Safe Processes
Published in James A. Klein, Bruce K. Vaughen, Process Safety, 2017
James A. Klein, Bruce K. Vaughen
The codes and standards discussed in Section 5.2.1 help designers with both processing, utilities and safeguarding equipment. For example, there are codes and standards for specific pressure vessel safeguarding equipment design. To prevent physically overpressurizing the vessel, pressure vessels must have a pressure relief system designed as its last line of defense. Pressure relief systems are sized depending on the potential overpressure scenarios, consisting of rupture disks, relief valves, or a combination of both. The relief system design includes the inlet and outlet sizes and must conform to the codes used to build the pressure vessel [8]. Industry codes also provide guidance on scenarios that should be considered and on equations for sizing of devices [15]. The potential overpressure scenarios include fire, blocked flow, control valve failure, overheating, power outage, tube rupture, and cooling water failure events. Runaway reactions may cause two-phase flow through the relief system, with specific modeling and design guidance provided by the Design Institute for Emergency Relief Systems (DIERS) [16].
Fire Hazards of Materials and Their Control
Published in Peter M. Bochnak, Fire Loss Control, 2020
Overpressure protection devices should be provided when failure of the pressure regulator could provide downstream pressures that might result in hazardous conditions or damage to equipment. These overprotection devices will take the form of pressure-relieving devices, automatic shutoffs, or regulators. Regulators are required when the gas supply pressure is higher than that at which the gas equipment is designed to operate or varies beyond the pressure limits designed into the equipment. Pressure regulators are equipped with diaphragms that can rupture. Consequently, they should be vented to a safe location outside the building. Under no circumstances should they be vented to the gas equipment flue or exhaust system.
Using the Information Harm Triangle to Identify Risk-Informed Cybersecurity Strategies for Instrumentation and Control Systems
Published in Nuclear Technology, 2023
Michael T. Rowland, Lee T. Maccarone, Andrew J. Clark
A more applicable control for most pressurizer systems is the overpressure relief valve that ensures the pressure boundary is always maintained. This is generally a mechanical device that opens to relieve excess pressure in the primary loop.