Piping design pressure, piping connected to equipment or vessels as a pressure system
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According to SH 3059, the design pressure of all pipes connected to equipment or containers as part of a pressure system shall not be lower than the design pressure of the connected equipment or containers. How should “as a pressure system” be understood here? For example, in the case of pumping material, does the pump’s outlet pipeline together with the downstream receiving tank constitute a pressure system?
“To function as a pressure system” means that the pipes and the devices or containers connected to them together endure the same operating pressures and conditions, and are designed and considered as a single unit. In the pump transfer operation you mentioned, if the pressure between the pump outlet pipe and the downstream receiving tank must remain consistent or if they affect each other’s normal operation, then they can be considered as a pressure system. .
Thank you for your reply. How is a single pressure system defined? Is it considered the same pressure system if they are connected? Does this mean that any pipe connected to the tank operates under the same system conditions as the tank? Must the design pressure be greater than the tank’s design pressure?
Yes, generally speaking, as long as the pipes and containers (such as tanks) are directly connected and share the same pressure or are subjected to identical pressure conditions during operation, they can be considered part of the same pressure system. Therefore, all pipes connected to the tank should indeed be considered as part of the same pressure system as the tank, and their design pressure should be at least equal to or greater than that of the tank, in order to ensure the safety and consistency of the entire system. .
I have the same question: for example, regarding the pipeline from the high-level tank to the reactor, is it designed based on the pressure rating of the reactor? This pipeline is only subjected to the static pressure generated by the liquid during operation, and the reactor itself operates at atmospheric pressure
Without valve shutdowns or pressure relief valves, it’s just one system; as long as the pressure is high enough for the equipment
The reaction vessel operates at atmospheric pressure, but its design pressure is certainly not atmospheric; there is no issue with the design pressure of the pipes in relation to the equipment
For example, the pressure at the pump outlet is 0.2 MPa; the fluid is transferred to the reactor, which operates at atmospheric pressure. However, the design pressure for the equipment itself is 0.6 MPa. There is a shut-off valve at the pump outlet. So what should be the design pressure for the entire pipeline?
The reaction vessel operates at atmospheric pressure. From a process perspective, the design pressure can also be set at atmospheric pressure when funding is allocated for the project. However, from the perspective of equipment manufacturers, whether the design pressure is 0.1 MPa or 0.6 MPa has little to no impact on the design, manufacturing, and production of the equipment. When making purchases, the client may provide the design agency with funds based on the higher design value; in such cases, what should be the design pressure for the connecting pipes?
I believe that the design pressure of the pipes should be sufficient to prevent overpressure at the source of pressure. You say this is a common practice. In the case of standard heat exchange equipment, the nominal pressure and design pressure are generally consistent, but actual operating conditions can vary greatly; in such situations, there is no basis for raising the design pressure of the pipes to match the design pressure of the equipment.