NAC455C.284. Blowoff piping and fittings.

     1. The construction of the setting around each blowoff pipe must allow free expansion and contraction. The openings for the setting must be sealed without restricting the movement of the blowoff piping.

     2. All blowoff piping, when exposed to heat from a furnace, must be protected by firebrick or other heat-resisting material so constructed that the piping may be inspected readily. Each boiler must have a blowoff pipe, fitted with a valve or cock, in direct connection with the lowest water space. Cocks must be of the gland or guard type and suitable for the pressure allowed. The use of globe valves must meet the requirements established by the American Society of Mechanical Engineers. If the maximum allowable working pressure exceeds 100 PSIG:

     (a) Each blowoff pipe must be provided with two valves or a valve and cock, and the valves and cocks must be made of extra-heavy steel, or bronze when listed as acceptable in table 126.1 of the Power Piping Code, as adopted by reference in NAC 455C.108, and must not be galvanized; and

     (b) The blowoff piping must be at least extra-heavy steel from the boiler to each valve and must be run full size without reducers or bushings.

     3. All fittings between the boiler and blowoff valve must be made of steel. In case of the renewal of the blowoff pipe or fittings, they must be installed in accordance with the requirements for new installations set forth in the Power Piping Code, as adopted by reference in NAC 455C.108.

     (Added to NAC by Div. of Industrial Relations by R101-02, eff. 12-15-2004)