Minnesota Administrative Rules
Agency 151 - Labor and Industry Department
Chapter 1346 - MINNESOTA MECHANICAL AND FUEL GAS CODES
MINNESOTA MECHANICAL CODE
Part 1346.1006 - SECTION 1006 SAFETY AND PRESSURE RELIEF VALVES AND CONTROLS

1006.4 Approval of safety and safety relief valves. Safety and safety relief valves shall meet the requirements of Section I, IV or VIII of the ASME Boiler and Pressure Vessel Code, as applicable. All boilers and pressure vessels shall have a safety relief valve stamped with the ASME code symbol and shall be set no higher than the maximum allowable working pressure of the pressure vessel. Safety relief valves shall have a rated volumetric capacity greater than the boiler or pressure vessel can produce at nameplate pressure and shall have a nonadjustable pressure set point below the rating of the boiler or pressure vessel capable of relieving all excess pressure at its pressure set point. Safety and safety relief valves shall have a manual method of lifting the seat, without endangering the operator, to ensure proper mechanical operation.

1006.6 Safety and relief valve discharge. Safety and relief valve discharge pipes shall be of rigid pipe that is approved for the temperature and pressure of the system. The discharge pipe shall be no smaller than the diameter of the safety or relief valve outlet and the discharge end shall be reamed and unthreaded. Safety and relief valves shall not discharge so as to be a hazard, a potential cause of damage, or otherwise a nuisance and shall terminate within 18 inches of the floor. High-pressure steam safety valves shall be vented to the outside of the structure in accordance with Minnesota Rules, parts 5225.4100 and 5230.0990 on boilers, pressure vessels, and high-pressure piping under the jurisdiction of the Department of Labor and Industry, as applicable. Where a low-pressure safety valve or a relief valve discharges to the drainage system, the installation shall conform to the Minnesota Plumbing Code, Minnesota Rules, Chapter 4715.

1006.9 Boiler shutdown switch. A manually operated remote shutdown switch shall be located as required by ASME CSD-1-2006.

Exception: A single hot water boiler with a rated input of less than 400,000 Btu/hr (117 kW).