The industrial safety valve is one of the most important parts in pressure systems, which has many applications in industries such as oil and gas, refineries, chemical industries, pharmaceuticals, and automobile manufacturing. These valves are installed in pressure systems to prevent sudden explosions. In this article, the operation of the safety valve is investigated.
1- The functional procedure of the safety valve
The industrial safety valve is installed on pressure pipes and if the pressure in this line exceeds the permissible limit, the valve opens and reduces the pressure. In order to achieve the correct operation of the industrial safety valve, it is necessary to pay attention to the correct installation methods. The best method for installation is to install it in a suitable place so that in the event of an explosion, no damage will be caused to other components of the system and the surrounding building.
2- The method of selecting and installing safety valves
Undoubtedly, having a high quality and standard safety valve is very important for pressure systems. The best way to choose industrial safety valves is to review the requirements of the API 520 standard.
3- Safety valve test
Testing of safety valves should be done periodically and continuously to ensure the correct functioning of the issued valve and also to ensure the safety of the system. These tests include the test to set the pressure to start and stop the operation of the safety valve and to check the amount of leakage in order to ensure the normal operation of the valve.
4-Supply of spare parts
When installing a safety valve, the ability to access spare parts is a critical consideration. A good supplier is able to provide spare parts for safety valves, which makes it easy and reliable to carry out repairs if necessary.
The performance of the industrial safety valve is very important and to ensure the quality and correct operation of the valve, the requirements of related standards must be taken into account. Reviewing the requirements of API 520 standard is one of the best ways to choose and install high quality safety valves.
Types of safety valves
- Spring safety valve
- Safety valve with pilot
- Weighted safety valve
- Vacuum safety valve
Type of safety valves
Valve body material is usually selected based on the pressure, temperature, corrosive and erosive properties of flow media.
- Cast carbon steel ASTM A 216 Gr. WCB is the common material for the valve body/bonnet in moderate service such as air, hot water, saturated steam and non-corrosive media.
- Cast Chrome-Moly steel ASTM A217 Gr. WC9 & WC6 or C5 has addition of chrome and molybdenum that provides corrosion resistance and also is suitable for superheated steam.
- Cast Type SS 304 (ASTM A351 Gr.CF8) is for oxidizing and very corrosive fluid.
- Cast Type SS 316 (ASTM A351 Gr.CF8M) is the same as SS 304 but since it has addition molybdenum then better has better corrosion resistance.
- Cast Iron (ASTM A126) is used for steam, gas, water and non-corrosive fluid and is inexpensive.
- Cast Bronze (ASTM B61 & B62) is used for air, hot water, steam, oil and non-corrosive fluid.
- Cast super alloy such as Inconel 625 & Hastalloy is used for off-shore applications and highly corrosive applications.
- Cast Al-Ni-Bronze (ASTM B148) is used for sea water applications.
- Cast Duplex SS Alloy 2205 for highly corrosive environment
- Cast carbon steel ASTM A352 Gr. LCC for low temperature application (-40 C)
Choosing the type of industrial valve (safety valve)
The choice of suitable materials by the manufacturer, considering the edge of the place where the valve works, is very important during the life of the valve, the efficiency of the valve and the performance of the valve. The compatibility of the type of valve with the fluid used in the engine and its physical capabilities and resistance to wear, fluid pressure and erosion caused by the fluid are the primary considerations that should be considered in choosing the type of valve.
The fluid that must pass through a valve is classified as follows:
- Gender
- Pressure
- Temperature
- Speed
and a subset of the following conditions:
- Its clarity and purity
- Stickiness
- Fluid viscosity
- Corrosiveness
- Being erosive
- Cooling
- According to the temperature and speed of the fluid and how the fluid passes, it causes erosion or not.
The presence of impurities is also determined in it.
At the end, the conditions that cause the fluid to pass through the valve or how the fluid in the process should be checked in terms of temperature, pressure and speed of the fluid.