Design of pipes behind safety valves for discharging liquids
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In safety relief specifications such as API520 and API521, they only describe the pipeline design of safety valves that discharge gas or the design of safety valves that discharge liquid and gas. They do not explain the pipeline design regulations after the safety valve that discharges liquid, that is, when the pipeline after the safety valve contains liquid phase fluid. Please check which specifications have design instructions for such issues, or what restrictions and factors need to be considered when designing the liquid phase pipeline behind the safety valve that discharges liquid.
Personally, I think the liquid phase pipeline behind the safety valve that releases the liquid should be lower.
This post was last edited by ZQJ at 2016-11-19 12:02 Design Specifications: It is the crystallization of the scientific practice and accident lessons learned by several generations of designers. There are many things that cannot be found in the specifications. But respect science. The most important thing for safety valve relief is accurate take-off pressure. In addition to valve production quality, the main factor affecting accurate relief is back pressure (except for special safety valves). Especially for liquid discharge, it is difficult to lower the pipeline in the back. This can cause the liquid level to accumulate or solidify, increase the back pressure, and cause serious production accidents. approach taken: 1. The pipelines at the rear should be designed to prevent freezing and condensation. ； 2. A relief container should be connected to the rear pipeline at a close distance to eliminate and maintain constant back pressure. 3. The top of the container is connected with a gas phase vent valve (breathing valves that can directly vent the atmosphere must also be designed to prevent freezing and condensation) or pressure balance control. 4. The discharged liquid must be drained cleanly from the container in time. Does not affect secondary discharge.
Thank you very much for the reply! In addition to the above factors to be considered, there is another situation: For example, if the equipment is a full liquid container, then the safety valve must discharge liquid. In this way, the specification only has the calculation of the safety valve that discharges the liquid, and there is no calculation of the liquid discharge pipe after the safety valve. When calculating this liquid discharge pipe, what are the general limitations and regulations that need to be considered in the calculation? Thank you!
Well, the relief pipe of the general safety valve is basically low, whether it is liquid or gas, and the branch pipe is inserted into the relief main pipe at a 45-degree angle.