Current through Register Vol. 51, No. 19, September 20, 2024
A. Number of
Valves.
(1) A hot water heating boiler shall
have at least one safety relief valve which is:
(a) Officially rated; and
(b) Set to relieve at or below the maximum
allowable working pressure of the boiler.
(2) A hot water supply boiler shall have at
least one safety relief valve which is:
(a)
Officially rated;
(b) Automatically
reseating; and
(c) Set to relieve
at or below the maximum allowable working pressure of the boiler.
B. A safety relief
valve with an officially rated capacity shall have pop action when tested by
steam.
C. When more than one safety
relief valve is used on a hot water heating or hot water supply boiler, each
additional valve shall be:
(1) Officially
rated; and
(2) Set at a maximum of:
(a) 6 PSI above the maximum allowable working
pressure of the boiler, for a boiler having a maximum allowable working
pressure of 60 PSI or less, or
(b)
10 percent above the maximum allowable working pressure, for a boiler having a
maximum allowable working pressure exceeding 60 PSI.
D. A safety relief valve shall be:
(1) Spring loaded; and
(2) Arranged so that it cannot be reset at a
pressure higher than the maximum permitted by this regulation.
E. A material that can fail
because of deterioration or vulcanization when subject to saturated steam
temperature corresponding to capacity test pressure may not be used for any
part.
F. Size.
(1) Except as otherwise provided by this
regulation, the standard pipe size of a safety relief valve may not be:
(a) Smaller than 3/4 inch; and
(b) Larger than 4-1/2 inches.
(2) A boiler having a heat input
of 15,000 BTU per hour or less may have a rated safety relief valve of 1/2 inch
standard pipe size.
(3) An inlet
opening shall have an inside diameter approximately equal to, or greater than,
the seat diameter.
(4) The minimum
opening through any part of a valve shall be at least 1/2 inch in diameter or
the equivalent area.
G.
Subject to the requirements of § I of this regulation, the minimum steam
relief capacity of a pressure relief device on a boiler, in pounds per hour,
shall be the greater of the capacity determined:
(1) By dividing by 1,000 the maximum BTU
output at the boiler nozzle, obtained by firing any fuel for which the unit is
installed; or
(2) In accordance
with Table
09.12.01.11B
G.
H. When operating conditions change or
additional boiler heating surface is installed:
(1) Valve capacity shall be increased, if
necessary, to:
(a) Meet the new conditions,
and
(b) Comply with this
regulation; and
(2) If
there is no intervening valve, any additional valves required because of
changed conditions may be installed on the outlet piping.
I. The safety relief valve capacity for a
boiler shall be sufficient to ensure that, with fuel burning equipment operated
at maximum capacity, pressure cannot exceed:
(1) 6 PSI above the maximum allowable working
pressure of the boiler, for a boiler having a maximum allowable working
pressure of 60 PSI or less; and
(2)
10 percent above the maximum allowable working pressure, for a boiler having a
maximum allowable working pressure greater than 60 PSI.
J. If there is any doubt as to the capacity
of a safety relief valve, an accumulation test shall be conducted in accordance
with the ASME Code, Section VI, Recommended Rules for the Care and Operation of
Heating Boilers.
K. A valve of any
type may not be placed:
(1) Between a safety
relief valve and a boiler; or
(2)
On a discharge pipe between a safety relief valve and the atmosphere.
L. Discharge Pipe.
(1) A discharge pipe shall be:
(a) At least full-size; and
(b) Fitted with an open drain to prevent
water from lodging in the upper part of a safety relief valve or in the
discharge pipe.
(2) If a
safety relief valve discharge pipe has an elbow, the:
(a) Elbow shall be located near the safety
relief valve outlet; or
(b)
Discharge pipe shall be securely anchored and supported.
M. Safety relief valve discharges
shall be located or piped so as not to endanger workers.
