A46Y Pilot Operated Safety Valves

Safety Valves Advantages:

Smaller package on the larger pipe sizes.

More options for control.

Seals more tightly as the system pressure approaches but does not reach set pressure.

Control pilot can be mounted remotely.

Some designs allow for changes in orifice size within the main valve.

Codes and Standards:

United States:

ASME (American Society of Mechanical Engineers) Boiler & Pressure Vessel Code, Section I

ASME (American Society of Mechanical Engineers) Boiler & Pressure Vessel Code, Section VIII, Division 1

API (American Petroleum Institute) Recommended Practice 520 and API Standard 526, API Standard 2000 (low pressure - Storage tank

European Union:

European standard steam boiler safety valveISO 4126 (harmonized with European Union directives)

EN 764-7 (former CEN standard, harmonized with European Union directives, replaced with EN ISO 4126-1)

AD Merkblatt (German)

PED 97/23/EC (Pressure Equipment Directive - European Union)

China:

JB/T308-2004

GB/T12241-2005

GB/T12243-2005

Design Features:

The pressure is supplied from the upstream side (the system being protected) to the dome often by a small pitot tube. The downstream side is the pipe or open air where the PORV directs its exhaust. The outlet pipe is typically larger than the inlet. 2”x3”, 3”x4”, 4”x6”, 6”x8”, 8x10” are some common sizes.