Pressure/Vacuum (PV) valves
Pressure/Vacuum valves are designed to provide protection of all cargo tanks against over/under pressure and provide for the flow of small volumes of tank atmosphere resulting from temperature variations in the cargo tank(s) and should operate in advance of the pressure/vacuum breaker, where IG system is in use.
Secondary PV System
To meet the requirements of SOLAS II-2, Part C, Reg. 11, 6.3.2, a secondary means of full flow venting for all tanks is to be provided – this is typically the combination of IG line P/V breaker / vent rise plus individual tank P/V valves. An alternative means of compliance is for a pressure monitoring and alarm system to be fitted. As this is the secondary means, the alarm is required to go off at a higher pressure than the P/V valve.
Reconditioning Procedure
Pressure/Vacuum valves are designed to provide protection of all cargo tanks against over/under pressure and provide for the flow of small volumes of tank atmosphere resulting from temperature variations in the cargo tank(s) and should operate in advance of the pressure/vacuum breaker, where IG system is in use.
Procedure Steps
- Disassembly
- Low pressure sandblasting (inner and outer)
- Construction of inox seat – valve and rectification
- Replacement of on-off lever
- Construction of bush (Teflon)
- Replacement of oring
- Replacement of spacer ring
- Construction of nuts and pins
- Construction of bolts
- Inside covering with Epoxik-adhesive resin
- Assembly
- Pneumatic pressure test
- External painting
Pressure Test
Repair works carried out as mentioned in our work specification and PV pressure tested /opened successfully at 0.14 mbar (or 1400mmwg). Pressure will depend upon the operating characteristics of the PV Valve.
1. Test bench connected to the PV Valve
2. All valves off
3. Air supply valve on
4. Pressure Reg. Valve is slowly opening
5. Pressure is 0,14 mbar and the valve is open
6. PV valves reconditioned
6. PV valves body painted and read to be assembled