Specification G2.2 Installation of boilers and pressure vessels
2. Boilers and pressure vessels
To specify the requirements for boilers and pressure vessels.
Clause 2.1 provides requirements for the distance between the vent of any explosion relief device and any adjacent wall, roof, ceiling or other solid construction. Table 2.1 provides the minimum clearance required which is based on the volume of the space being vented. The minimum clearance is determined by a formula which includes the volume of the space being vented. The intention of the explosion relief provisions are that in the event of an explosion the extent of damage is limited.
The minimum clearance determined in the first row is 0.4 m from an adjacent wall or ceiling/roof.
The minimum clearance determined in the second row is 0.6 m from two walls at right angles, or one wall and a ceiling/roof. This scenario poses a higher risk of damage from overpressure experienced during deflagration, therefore the clearance is increased.
Examples of compliance with Table 2.1
V = Volume of space being vented (e.g. furnace to the flue connection)
For this example the volume is 5 m3
x = Clearance from adjacent wall or ceiling/roof
y = Clearance from two walls at right angles; or one wall and a ceiling/roof
x = 0.4(V/3)1/3
x = 0.4(5/3)1/3
x = 0.47 m
Therefore the minimum clearance is 0.47 m.
y = 0.6(V/3)1/3
y = 0.6(5/3)1/3
y = 0.71 m
Therefore the minimum clearance is 0.71 m.
Floor and drainage
Clause 2.2 contains two parts. The first is to require the floor surface beneath the boiler or pressure vessel to be water resistant and the floor to be graded away from supports and structural building elements. The second is to ensure that where a safe tray is provided, it must be of a material that is resistant to corrosion from the contents of the boiler.
Protection from heat
For steel, concrete and timber elements, Clause 2.3 requires the protection of these elements to prevent exposure to certain temperatures emitted by a boiler or pressure equipment.
2.1 Explosion relief
The distance between the vent of any explosion relief device and any adjacent wall, roof, ceiling or other solid construction shall be calculated in accordance with Table 2.1.
|Minimum clearance (metres)
|Adjacent wall or ceiling/roof
|0.4(V/3)1/3 or 0.4 m, whichever is the greater
|Two walls at right angles; or one wall and a ceiling/roof
|0.6(V/3)1/3 or 0.6 m, whichever is the greater
2.2 Floors and drainage
2.3 Protection from heat
Building elements surrounding a boiler must be protected from any surface heat by refractory material or effective air spaces so that—
steel elements do not exceed a temperature of more than 300°C; and
concrete elements do not exceed a temperature of more than 200°C; and
timber elements do not exceed a temperature of more than 150°C.