A safe relief valve, also known as a safety relief valve, is an automatic pressure relief device driven by medium pressure. According to different usage scenarios, it can be used as both a safety valve and a relief valve.

Taking Japan as an example, there are relatively few clear definitions for safety valves and relief valves. Generally, safety devices used for large energy storage pressure vessels such as boilers are called safety valves, while those installed on pipelines or other facilities are called relief valves. However, according to the "Technical Standards for Thermal Power Generation" of the Japanese Ministry of International Trade and Industry, the use of safety valves is an important part of equipment safety protection, such as boilers, superheaters, reheaters, etc. In situations where the lower side of the pressure reducing valve needs to be connected to the boiler and turbine, a relief valve or safety valve needs to be installed. From this perspective, safety valves require greater reliability than relief valves.

In addition, from the high-pressure gas management regulations of the Japanese Ministry of Labor, the regulations of the Ministry of Transport, and various levels of ship associations regarding the recognition and regulation of safe emissions, we refer to valves that ensure emissions as safety valves, while valves that do not guarantee emissions are referred to as relief valves. In China, whether fully open or slightly open, they are collectively referred to as safety valves.

I. Overview

Safety valves are important safety accessories on boilers, pressure vessels, and other pressure equipment. The reliability and performance of its actions are directly related to the safety of equipment and personnel, and are closely related to energy conservation and environmental protection. And some users and design departments always choose the wrong model when selecting.

2、 Definition

In a broad sense, the so-called safety valve includes a relief valve. From the perspective of management rules, when directly installed on steam boilers or pressure vessels, the necessary condition is that the valve must be recognized by the technical supervision department. Narrowly defined, it is called a safety valve, while others are generally referred to as relief valves. The safety valve and the relief valve are very similar in structure and performance, both of which automatically discharge the internal medium when the opening pressure is exceeded to ensure the safety of the production equipment. Due to the inherent similarity between the two, people often confuse them when using them. In addition, some production facilities also specify which one can be used according to the rules. Therefore, the differences between the two are often overlooked. As a result, many problems have arisen. If a clearer definition of the two is to be made, it can be understood according to the definition set forth in Section 1 of the ASME Boiler and Pressure Vessel Code:

(l) A safety valve is an automatic pressure relief device driven by the static pressure of the medium in front of the valve. Its characteristic is a fully open action with a sudden opening. Used for gas or steam applications.

(2) Relief valve, also known as overflow valve, is an automatic pressure relief device driven by the static pressure of the medium in front of the valve. It opens proportionally as the pressure exceeds the opening force. Mainly used in fluid applications.