• Inspection and maintenance

INSPECTION & MAINTENANCE OF HIGH VELOCITY P/V VALVES

For vessels that have type-approved end-of-line high-speed pressure-vacuum valves (High Velocity P/V Valves) installed, it is recommended that the following inspection- /maintenance routines are implemented in order to keep the valves in proper operating condition.

Procedure

Preparation for Cargo Operation

Purpose

Check for Free Movement

Recommended interval 

Before Any Cargo Operation 


Procedure: Preparation for Cargo Operation The purpose of this inspection is to ensure full functionality and free movement of the valve;

  • Operate check-lift and ensure free movement of the pressure valve (Acc. to SOLAS Reg. 10, b (i)).
  • Operate check-lift and ensure free movement of the vacuum side (Acc. to SOLAS 10, b (i)).
  • Inspect the Mesh Element/Filter on the Vacuum side and Inspect Seat and Disc on the Pressure side. Clean if found necessary.

Warning: If the valve does not move freely, the cause should be determined and corrected immediately.

Procedure

Recurring On-board Inspection

Purpose

Inspections for Deposits & Wear

Recommended interval 

Minimum every 6 months (1*)


Procedure: Recurring Onboard Inspection The purpose of this inspection is to ensure that the valve’s performance has not limited due to damages, wear an and deposits (cargo residues etc.). Inspection frequency depends on its operating conditions and the type of cargoes carried (*1);

  • Check Free Movement according to procedure “Preparation for Cargo Operation”
  • Inspect “Deposit Indicators” to estimate the level of internal deposits and residues
  • Clean and visually check seat and disc on the pressure side for deposits, groves and “dent marks”
  • Visually check filters/mesh element on the vacuum side for deposits and particles
  • Grease the check-lift handle(s) with a minimum amount of grease (if required)
  • If applicable, remove the mesh element/filter on the vacuum side and clean/inspect the vacuum seat and

If the valve shows any signs of malfunction, damages in seat/disc or a significant amount of deposits/residues, a detailed inspection of the valve and necessary corrective actions must be taken (Please refer to the valve’s maintenance manual).

Procedure

Special Survey Overhaul & Test

Purpose

Valve overhaul

Recommended interval 

Minimum Every 5 Years


Procedure: Recurring Onboard Inspection The purpose of this inspection is to ensure that the valve’s performance has not limited due to damages, wear an and deposits (cargo residues etc.). Inspection frequency depends on its operating conditions and the type of cargoes carried (*1);

  • Check Free Movement according to procedure “Preparation for Cargo Operation”
  • Inspect “Deposit Indicators” to estimate the level of internal deposits and residues
  • Clean and visually check seat and disc on the pressure side for deposits, groves and “dent marks”
  • Visually check filters/mesh element on the vacuum side for deposits and particles
  • Grease the check-lift handle(s) with a minimum amount of grease (if required)
  • If applicable, remove the mesh element/filter on the vacuum side and clean/inspect the vacuum seat and

If the valve shows any signs of malfunction, damages in seat/disc or a significant amount of deposits/residues, a detailed inspection of the valve and necessary corrective actions must be taken (Please refer to the valve’s maintenance manual).

Procedure: Special Survey Overhaul & Test

The purpose of this overhaul is to verify that the valve operates according to its specifications and type-approval;

  • Clean all internal and external parts of the valve
  • Replace or repair any part of the valve that shows signs of substantial wear or tear.
  • Ensure free movement of all moving.
  • Check and adjust the opening setting of the pressure valve by means of a Test Rig (or similar equipment).
  • Check the opening set of the vacuum valve by means of a Test Rig (or similar equipment).

If leakage is suspected, please perform a leak test. 

Cleaning & Repair

All parts can be cleaned by means of a cleaning pad or brush and a thin lube oil (or a suitable detergent). If required, the mesh element/filter can be “soaked” in a suitable detergent.

Lapping (“slightly”) of disc and seat will generate an abrasive effect that can improve the sealing between disc and seat. (Caution: The pressure valve must always be pressurized to at least 80 % of the nominal setting during lapping). Lapping will have little or no effect on a damaged valve seat and/or disc.

Warning: Machining of the valve’s seat and the disc is not recommendable under any circumstances. Machining can change the valve’s characteristics significantly and thus compromise the safety for vessel and crew.

Spare Parts:

In order to maintain the valve’s type of approval, the only type approved spare parts should be used. Original PRES-VAC Spare Parts is recommended.

Test of the P/V Valve

Function Test: Both the vacuum- and pressure side must operate freely (Acc. to the procedure “Preparation for Cargo Operation”).

Opening Setting (Pressure- & Vacuum Side):

The opening setting shall be within ±0,5 kPa or ±6 % of nominal setting, whichever is the lowest. 

Leakage: The leakage rate should be within the allowed limits for the specific size of P/V-Valve (Ref. PV-table no. 1192-129).

Contact
  • Pres-Vac Engineering A/S
    Solvang 22
    3450 Allerød
    Denmark
    Phone: +45 48 17 40 55 
    Email: presvac@pres-vac.com