§ 3a.27. Different working pressures.
(a) At least one safety valve on each boiler must be set at or below the maximum allowable working pressure. All other valves may be set within a range of 3% above the maximum allowable working pressure. The range of setting of all of the saturated steam valves on the boiler may not exceed 10% of the saturated steam valve set at the highest pressure.
(b) When a boiler system is comprised of boilers with different maximum allowable working pressures having minimum safety valve settings varying more than 6% and connected so that steam flows toward the lower pressure boiler, the boiler system must meet one of the following requirements:
(1) A check valve must be installed in the steam line to protect the lower pressure boilers.
(2) Additional safety valves on the low-pressure side of the boiler system must protect lower pressure boilers and meet the following requirements:
(i) The additional safety valve capacity must be based on the maximum amount of steam that can flow into the low-pressure system.
(ii) Additional safety valves must have at least one valve set at a pressure that is not greater than the lowest maximum allowable pressure.
(iii) Other valves must be set within a range of not more than 3% above the lowest allowable pressure.
No part of the information on this site may be reproduced for profit or sold for profit.
This material has been drawn directly from the official Pennsylvania Code full text database. Due to the limitations of HTML or differences in display capabilities of different browsers, this version may differ slightly from the official printed version.
