ASME BPVC 2023 Section XIII

PART 3
REQUIREMENTS FOR PRESSURE RELIEF VALVES
3.1 GENERAL
3.1.1 Applicability of Part 3 Requirements
This Part contains requirements applicable to all pressure
relief valves that are to be marked with the Certification
Mark and any Designator. Requirements unique to a
specific Designator are identified.
ð23 3.1.2 Valve Characteristics
a All pressure relief valves shall be of the direct
spring-loaded, pilot-operated, or power-actuated type.
b Pilot-operated pressure relief valves shall be
designed such that
1 the pilot is self-actuated
2 the main valve will open automatically at a pressure
not exceeding the set pressure
3 if some essential part of the pilot fails, the main
valve will discharge its full rated capacity at or below the
relieving pressure used to determine its rated capacity
c Section VIII, Division 1 and Division 2 UV Designator
pressure relief valves shall be designed and
constructed such that when installed per Section VIII,
Division 1, UG-156, they comply with the following:
1 They shall operate without chattering.
2 When operating at the flow-rated pressure, they
shall not flutter in a way that would either interfere with
the measurement of capacity or result in damage.
3.2 DESIGN AND MECHANICAL REQUIREMENTS
3.2.1 Body
In the design of the body of the pressure relief valve,
consideration shall be given to minimizing the effects of
deposits.
3.2.2 Drains
a If the design of a pressure relief valve is such that
liquid can collect on the discharge side of the disk, then,
except as permitted in b, the valve shall be equipped with
a drain at the lowest point at which liquid can collect.
b Pressure relief valves that cannot be equipped with
a drain as required in a because of design or application
may be used, provided all the following conditions are
met:
1 The pressure relief valves are used only on gas
service where there is neither liquid discharged from the
valve nor liquid formed by condensation on the discharge
side of the valve.
2 The pressure relief valves are provided with a
cover or discharge piping per 12.8c to prevent liquid
or other contaminant from entering the discharge side
of the valve.
3 The pressure relief valve is marked FOR GAS