Boilers must be equipped with safety valves according to their rated evaporation capacity. Specifically, any steam boiler with a rated evaporation exceeding 0.5 tons per hour must have at least two safety valves. For boilers with a rated evaporation of 0.5 tons per hour or less, a single safety valve is sufficient. In addition, all separable economizers and steam superheaters must also have safety valves installed to ensure safe operation under high-pressure conditions.
Safety valves should be mounted vertically in the highest position on the boiler drum and headers. It is crucial that no outlet pipe or valve is placed between the safety valve and the drum or header, as this could interfere with the proper release of pressure during an emergency.
For lever-type safety valves, there must be mechanisms in place to prevent the hammer from moving unintentionally and a guide system to stop the lever from derailing. Spring-type safety valves, on the other hand, should include a handle for easy lifting and a locking mechanism to prevent the adjustment screw from being turned accidentally.
The throat diameter of the safety valve is important for performance. Boilers operating at a rated steam pressure of 3.82 MPa or lower must have a throat diameter of at least 25 mm. For higher-pressure systems, above 3.82 MPa, the throat diameter should not be less than 20 mm to ensure proper flow and pressure relief.
The connection pipe between the safety valve and the boiler must have a cross-sectional area equal to or greater than the inlet area of the safety valve itself. If multiple safety valves are installed on a short pipe connected directly to the drum, the short pipe’s cross-sectional area should be at least 1.25 times the total exhaust area of all the safety valves combined.
Each safety valve should also have an exhaust pipe that leads to a safe location. The exhaust pipe must have enough cross-sectional area to allow unobstructed discharge of steam. At the bottom of the exhaust pipe, a drain line should be installed and connected to a safe area. Importantly, no valves should be placed on either the exhaust or drain pipes to avoid restricting the flow during critical situations.
These requirements are essential for ensuring the safe and efficient operation of steam boilers, preventing overpressure incidents, and protecting both equipment and personnel. Proper installation and maintenance of safety valves are key to compliance with industry standards and operational reliability.
Ratchet Buckle,4 Inch Ratchet Buckle,Handle Ratchet Buckle,Painted Ratchet Buckle
Jiangsu Zhongyi Tools and Riggings Co., Ltd. , https://www.zy-rigging.com