A steam boiler is a closed vessel that boils water to generate saturated or superheated steam. Back in the 19th century, the explosion of steam boilers was a common occurrence. To overcome the challenge, companies conducted independent examinations to reduce the possibility of an explosion and determine its cause. It eventually led to the manufacturing and installation of mountings and fittings on steam boilers that enhanced the safety of the boiler system over time. Mountings on a steam boiler are a set of safety devices installed for the safe operation of a boiler. It safeguards the steam boiler from harm caused due to extreme pressure, low water level, steam backflow, unregulated steam pressure, shell collapse due to vacuum, backflow of feed water to the pump, and dry running.
What is Steam Boiler Mountings?
Steam boiler mountings are fittings, mounted on the steam boiler to ensure its proper functioning. Boiler mountings include water level indicator, safety valve, pressure gauge, etc. It is necessary to note that a boiler cannot function safely without the mountings. These fittings mounted on the steam boiler are required mandatorily for the safe and proper operation of the boiler system.
The primary mountings in the steam boiler are:
- Water level indicator
- Pressure gauge
- Safety valve
- Steam stop valve
- Blow off valve
- Feed check valve
- Fusible plug
- Water Level Indicator:
A water level indicator is installed outside the steam boiler shell to determine the water level in the boiler through a glass tube. It is safety equipment that ensures the safe operation of the steam boiler.
The Water-tube indicator consists of a vertical hard glass tube that is fitted with two gunmetal tubes A and B. Tube A and B join the steam space of the boiler and the water space of the boiler with the glass tube respectively.
Tube A is fitted with a valve, called a steam valve, and tube B is provided with another valve called a water valve. Additionally, a third valve called the drain valve is fitted to the water level indicator. The drain valve helps in periodically draining the water together with condensed steam from the gunmetal tube A.
- Pressure Gauge:
A pressure gauge indicates the steam pressure in the boiler. It is mounted usually on the front top of the steam boiler.
The pressure gauge consists of a circular spring tube A. One end of the tube is closed and joined to a link, while the other end is to a hollow block. The link connects the closed end of the tube to the toothed sector that is hinged. The toothed sector gears with a pinion that carries a pointer. The pointer moves on a dial, indicating the pressure units.
- Safety Valve:
The safety valve is a safety mounting fitted on the steam boiler shell and is crucial on the boiler shell to ensure the safety of the boiler against high pressure. It prevents explosions due to excessive internal steam pressure in the boiler system.
The safety valve is equipment to prevent the increasing steam boiler pressure above its operating pressure. It opens automatically as the pressure in the steam boiler exceeds the normal working pressure. Therefore, it allows excess steam to release into the atmosphere until the pressure returns to its normal valve. A safety valve ensures the safety of the steam boiler from damages due to excessive steam pressure.
The primary types of safety valves include:
Deadweight safety valve
Lever safety valve
Spring-loaded safety valve
- Steam Stop Valve:
A steam stop valve controls the steam flow from within the steam boiler and stops it completely when required. A steam stop valve regulates the steam flow from the boiler system.
The valves mounted on the steam boilers that change the direction of steam flow by 90° are known as junction valves. On the other hand, valves fitted in pipelines that allow the steam in the same direction are called stop valves.
- Blow-Off Valve:
The blow-off valve helps in periodically removing the sediments that are deposited at the bottom of the steam boiler while it is in operation and emptying the steam boiler during its cleaning or inspection.
As the blow-off valve is opened, the water under the pressure of steam rushes out with high velocity and releases the sediments along with it.
- Feed Check Valve:
With the falling level of water in the steam boiler, it is revived to the specified level by supplying excess water. It is known as feed water. The pressure in the boiler will be high, consequently increasing the feed water pressure by a pump before feeding it to the steam boiler. The feed water under high pressure is fed to the boiler system through the feed check valve.
The feed check valve controls the water flow from the feed pump and prevents the backflow of water from the boiler system to the pump. Therefore, the feed check valve is located at the boiler end of the delivery pipe of the feed pump.
- Fusible Plug:
The fusible plug consists of tin or lead alloy of low melting point. The fusible plug puts off the fire in the furnace of the steam boiler as the water level falls below the safe level and thus prevents the explosion that may result from overheating of the tubes and the shell. It is fitted at the apex of the furnace or the combustion chamber.
Conclusion:
Rakhoh Boilers are renowned for their efficient and reliable steam boilers, waste heat recovery boilers, thermic fluid heaters, and boiler accessories since their inception in 1983. We also provide excellent boiler services like energy audit, steam trap assessment, boiler automation, annual boiler maintenance, fuel conversion, etc., to enhance the efficiency and productivity of steam boilers.
Learn more about our products and services at www.rakhoh.com