The pressure vessel of a boiler is usually made of steel (or alloy steel), or historically of wrought iron.
In the 20th century, design practice instead moved towards the use of steel, which is stronger and cheaper, with welded construction, which is quicker and requires less labour.
It should be noted, however, that wrought iron boilers corrode far slower than their modern-day steel counterparts, and are less susceptible to localized pitting and stress-corrosion.This makes the longevity of older wrought-iron boilers far superior to those of welded steel boilers. Cast iron may be used for the heating vessel of domestic water heaters.
Another possibility, much simpler and more convenient, is now using the Internet, and there on special pages or forums, you will find plenty of tips and tricks that will allow us to easily be repaired.
Pressuretrols to control the steam pressure in the boiler..Boilers generally have 2 or 3 pressuretrols: a manual-reset pressuretrol, which functions as a safety by setting the upper limit of steam pressure, the operating pressuretrol, which controls when the boiler fires to maintain pressure, and for boilers equipped with a modulating burner, a modulating pressuretrol which controls the amount of fire. Safety valve: It is used to relieve pressure and prevent possible explosion of a boiler. Water level indicators: They show the operator the level of fluid in the boiler, also known as a sight glass, water gauge or water column. Bottom blowdown valves: They provide a means for removing solid particulates that condense and lie on the bottom of a boiler.As the name implies, this valve is usually located directly on the bottom of the boiler, and is occasionally opened to use the pressure in the boiler to push these particulates out. Continuous blowdown valve: This allows a small quantity of water to escape continuously.Its purpose is to prevent the water in the boiler becoming saturated with dissolved salts.
Saturation would lead to foaming and cause water droplets to be carried over with the steam ? a condition known as priming.
Blowdown is also often used to monitor the chemistry of the boiler water. Flash tank: High-pressure blowdown enters this vessel where the steam can 'flash' safely and be used in a low-pressure system or be vented to atmosphere while the ambient pressure blowdown flows to drain. Automatic blowdown/continuous heat recovery system: This system allows the boiler to blowdown only when makeup water is flowing to the boiler, thereby transferring the maximum amount of heat possible from the blowdown to the makeup water.
No flash tank is generally needed as the blowdown discharged is close to the temperature of the makeup water.Źródło: https://en.wikipedia.org/wiki/Boiler