Components and assemblies
In addition to the boiler body itself, the maximum permissible operating overpressure and the maximum permissible temperature of all components and assemblies directly connected to the boiler must also be observed. These include, in particular, fittings, sensors, pipes, seals and apparatus.
Pressure-temperature curve for flanges in accordance with EN 1092-1
A key difference between hot water boiler and steam boiler systems lies in the way pressure is generated. In hot water boilers, the operating pressure is not imposed on the system by the combustion system, but by a pressure maintaining system. This pressure maintenance fulfils several safety-related tasks:
- Compensation for pressure fluctuations caused by temperature fluctuations or water losses
- Ensuring a minimum pressure in the system to prevent the formation of vapour bubbles (evaporation)
Reliable pressure maintenance is therefore essential for trouble-free and safe operation.
Safety measures during the design
The difference between the determined pmax,perm and the maximum permissible overpressure of the next higher boiler pressure stage can already be considered as design safety. If additional design reliability is required for the pressure range, this can be achieved by selecting a correspondingly higher boiler pressure rating.