The boiler is a devsteamice used to produce steam. The temperature in the boiler is very high so that the pressure is also high. Therefore, the steam system needs to be kept safe. One type of automatic safety device that is needed in steam systems is the safety valve in the boiler system.
Safety Valve Function in Boiler System
The safety valve will protect the tools and devices from hazards caused by temperature and force due to excessive vapor pressure in the system. So, the safety valve will open and remove excess steam if the pressure and temperature in the steam system exceeds the set point limit (set conditions).
In addition, the safety valve also functions to remove steam that has become condensate so that it does not enter the turbine and cause corrosion in the turbine.
The safety valve must be in accordance with the latest steam system developments. Safety valves should be reviewed periodically depending on unit standards, company guarantee recommendations and government laws. The American Society of Mechanical Engineers (ASME) is a department that regulates safety valves. ASME has upgraded the boiler and pressure vessel for safety valves.
In the United States, a big consideration for safety valves is choosing the right size followed by the correct installation. This article will discuss about the Safety Valve installation in the Boiler System.
The right size in the safety valve
The following sizes are recommended for the safety valve:
- The set point of the safety valve is recommended that the delta formed between the steam and regulated operating pressure is at least 20%.
- When considering the downstream flow capacity of the safety valve from the steam pressure control valve, the total capacity of the safety valve at the set point must exceed the maximum flow capacity of the steam pressure control valve. The steam pressure entering the valve shall be calculated at the maximum safety valve setting of the steam supply source
- The safety valve size does not exceed the design calculation. Excessive safety valve in this case is not good because it can cause an unpleasant sound, leakage and damage to the safety valve.
- Single safety valve cannot be done because of its large capacity, limited physical condition of the safety valve and economic considerations.
- The pressure set on the safety valve should be set at or below the Maximum Allowable Working Pressure (MAWP) of the component with the lowest sent point in the system. On the other hand, two components in the same system with different pressures, will be protected by security devices.
Stages of Installing a Safety Valve in a Boiler System
The following are the stages of installing a safety valve in a boiler system:
- The steam system must be conditioned to be clean and free from dirt or sedimentation before installing the steam system with a safety valve.
- The safety valve is mounted vertically with the spindle on the valve in a vertical state.
- The steam pipe entering the safety valve must be equal to or greater than the connection to the safety valve.
- There is no connection at the valve location between the intake safety valve and the steam components isolating the system.
- Ensure that the channel or open hole on the safety valve is not filled with air.
- The safety valve is regulated and guaranteed to prevent the temperature rising. if the wire is open then the valve is unsafe and cannot be used. Contact the supplier as soon as possible if this happens
- For multi-safety valve installations using a single connection, the internal cross-sectional intake area should be the same as the combined entry area for the entire safety valve.
For further information, it is advisable to consult and discuss with experts so that mistakes do not occur considering that the safety valve is very important to protect the potentially hazardous steam system.