Mich. Admin. Code R. 408.4246 - Blowoff connections; existing power boilers

Rule 246.

(1) The construction of the setting around each blowoff pipe shall permit free expansion and contraction. Careful attention shall be given to the problem of sealing these setting openings without restricting the movement of the blowoff piping.
(2) All blowoff piping, when exposed to furnace heat, shall be protected by firebrick or other heat-resisting material, so constructed that the piping may be inspected readily.
(3) Each boiler shall have a blowoff pipe, fitted with a valve or cock, in direct connection with the lowest water space. Cocks shall be of the gland or guard type and suitable for the pressure allowed. The use of globe valves shall not be permitted.
(4) When the allowable working pressure exceeds 100 psi gauge, each blowoff pipe shall be provided with 2 valves or a valve and cock, such valves and cocks to be at least of the extra-heavy type.
(5) When the maximum allowable working pressure exceeds 100 psi gauge, blowoff piping shall be at least extra-heavy and shall be run full size without use of reducers or bushings. The piping shall be at least extra-heavy wrought iron or steel and shall not be galvanized.
(6) All fittings between the boiler and blowoff valve shall be of steel.

In case of renewal of blowoff pipe or fittings, they shall be installed in accordance with the rules and regulations for new installations.

(7) Each steam heating boiler shall have a blowoff pipe connection fitted with a valve or cock not less than 3/4 inches pipe size connected with the lowest water space practicable.

Notes

Mich. Admin. Code R. 408.4246
1979 AC

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