Minn. R. agency 151, ch. 5205, STEAM BOILERS, pt. 5205.0330
The requirements of this item shall not apply to heating plants in buildings occupied solely for residence purposes, with accommodations therein not to exceed four families; to railroad locomotives; nor to railroad locomotive engineers employed by railroad companies.
Any steam boiler with a safety valve set to permit a pressure exceeding 15 pounds shall be considered a high-pressure steam boiler.
Safety valves shall not discharge within seven feet of floor, platform, ground, or boiler top, across a passageway or foot-walk or in such a way as to endanger persons operating stop valves. The arrangement of piping must not be such as to create a back pressure on the safety valve.
Open blowoffs shall not discharge within seven feet of floor, platform, or ground, across a passageway.
Safe exit from all parts of boiler room shall be provided by at least two stairways, ladders permanently fastened in place, or other means of exit.
An effective valve locking device is one which will prevent any motion of the valve stem, and which is so attached to the valve that it cannot be removed. When two or more boilers are connected to a common steam, feedwater, or blowoff line, at least one controlling valve in the connection from each boiler to each such common steam, feed-water, or blowoff line shall be equipped with an effective valve locking device; and whenever a person is working in any boiler of a battery, the steam, feed-water and blowoff valves shall be closed and locked.
A nonreturn valve is one which will automatically close and prevent steam from the main line from flowing back into the boiler if the pressure in the latter should fall below that in the steam line. Where two or more boilers are connected to one steam line, a nonreturn valve shall be provided in the main steam connection of each boiler, either in addition to or combined with the regular stop valve.
Minn. R. agency 151, ch. 5205, STEAM BOILERS, pt. 5205.0330
Statutory Authority: MS s 182.657