IBC SL Series Installation & Operating Manual page 49

Warning
During operation, the relief valve may discharge large amounts of steam and/or hot water.
To reduce the potential for bodily injury and property damage, install a discharge line that:
Is connected from the valve outlet with no intervening valve and directed
downward to a safe point of discharge.
Allows complete drainage of both the valve and the discharge line.
Is independently supported and securely anchored, so as to avoid applied stress
on the valve.
Is as short and straight as possible.
Terminates freely to atmosphere where any discharge will be clearly visible and is
at no risk of freezing. terminates with a plain end which is not threaded.
Is constructed of a material suitable for exposure to temperatures of 375° F or
greater.
Is, over its entire length, of a pipe size equal to or greater than that of the valve
outlet.
Do not cap, plug or obstruct the discharge pipe outlet.
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3.11 Water Piping