The issue of the relief valve’s discharge area

According to the provisions of Appendix B.2.2 of standard GB12337-2014, for spherical tanks storing explosive liquefied gases, it is required to install 2 safety valves, and the discharge capacity of each safety valve must be greater than the accident discharge capacity of the spherical tank. This is to ensure that overpressure can be released promptly and effectively in the event of an accident, thereby protecting the safety of equipment and personnel. Therefore, for the medium-pressure drum you mentioned, the discharge capacity of each safety valve must be greater than or equal to the equipment’s safe discharge capacity in order to meet the requirements for selecting and calculating safety valves. .

Theoretically, it is of course the safety valve at the design pressure or the maximum allowable operating pressure that must meet the discharge requirements, as stipulated in the higher-level technical specification TSG 21-2016. The statements in Appendix B of GB150-2011 are misleading and confusing; GB12337-2014 provides supplementary explanations to avoid such misunderstandings.

I agree with you, thank you! Since it is rare to encounter situations where two safety valve outlets are installed on ordinary equipment, I discussed this issue with an experienced engineer at the company; he felt that the total discharge capacity of the two safety valves should be sufficient to meet the equipment’s safety discharge requirements. We disagreed on this point, which is why I am seeking advice from everyone here. Thank you! :handshake

Not every device is equipped with two safety valves; different safety valves serve different purposes. For example: 1. One in use and one as a backup； This allows the safety valve to be removed for inspection without shutting down the equipment ； 2. Meeting the discharge requirements: Since an increase in the diameter of the safety valve leads to higher costs, a design approach that involves using two or more smaller safety valves to meet the discharge requirements of a single larger safety valve can be considered; in this case, these safety valves can be treated as one entity ； 3. Improve safety: There’s no need to elaborate on this – it prevents safety valves from failing and provides additional means of pressure release; it is generally used in harsh operating conditions or situations with a high risk level ； 4. One high and one low: This configuration requires that one safety valve meet the equipment’s requirements regarding safe discharge capacity. The arrangement of one high and one low is used in devices that generate pressure, aiming to provide space for handling operations as well as to enable additional discharge ； 5. Warning and auxiliary function: A small safety valve is installed with a setting pressure that is higher than the operating pressure but much lower than the design pressure; however, this safety valve cannot meet the discharge requirements, which must be satisfied by the main discharge device.

GB12337 is a standard for spherical tanks; it applies to explosive liquefied gases and is not suitable for medium-pressure steam drums. According to regulation 150, the old engineer’s opinion is correct. The image shows the draft of the new 150; it might be written more clearly.

Not exceeding the design pressure or the maximum allowable operating pressure. Whether it’s technical specifications or standards, everything is explained clearly.

The draft version of GB150 is just more detailed, with higher requirements in certain areas; this will lead to stricter enforcement of the corresponding technical standards, resulting in higher costs for design, manufacturing, and use. Also, what you’ve posted here does not support the opinion of the senior engineer; on the contrary, it supports the opinion of the original poster.

Each one can meet the total discharge volume, but the constant pressure values are different. What is the purpose of him doing this?