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THE HIDE SERIES – The new generation G-valves

The most common failures due to malfunction of tank vent check valves are related to either water ingress or abnormal pressure in tank.


Water ingress typically occurs when the ship is listing heavily and the valves are completely or partially submerged. If the float is stuck, damaged or missing, the tank will take in water through the vent valve. Such a situation can rapidly become serious, especially if no pump can be activated due to electrical failure or missing machinist on board.

Abnormal tank pressure is a result of blocked or chocked air flow through the vent valve. Both over and underpressure caused by a stuck float can create significant stress levels in tanks or hull structure. In worse case, this could lead to structural breakdown due to suction blocking or overfilling of tank. Correct dimensioning of tank venting is therefore essential to avoid abnormal pressures.

The reliability of the valves is of the highest importance for safety at sea. John Gjerde AS believes in continuous innovation and our mission is to improve the safety of the crew, their vessels and the environment. We have solid in-house competence and can rely on own test facilities to study all safety aspects related to our products.

Patent No.: 10-1642210

HIDE quality pays off!

Did you know that the unique HIDE winterization solution appears as the most economical in the market?


The 80% savings during installation pays for the entire shipset. In addition, 80% fuel and NOX savings also pays for the entire shipset one more time after only one year in operation.

This position the HIDE quality valves as the most economical and green air vent check valves in the market.

The unique savings are due to a self-regulating heating element, that is optimally located, spending only the necessary power to ensure function. The solution requires 95% less cables, 95% less MCB, and 45kw less generator effect for a shipset of 80 valves.

Unique advantages of HIDE Patent No.: 10-1642210

John Gjerde believe in continuous innovation to improve the safety for the crew, their vessels and for the environment.

John Gjerde have solid in-house competence using our own testing facilities for studying the safety aspects of ships.

The unique advantages of the HIDE valve are:

1.  The guiding pin, which ensure perfect performance even under tilted conditions.

2. The unique disc-float shaped for optimal airflow with integrated lip seal gaskets

  • Provides protection against damage from overfilling
  • Provides efficient noise suppression and “clapping” of float
  • Prevents leakage in dipping situations. The disc and pin concept protects the closing mechanism and makes the  G-valve the most reliable valve in the market


3.  The cross-section area inside the valve is larger than the air flow area required by the This decreases the risk of “suction blocking” and structural breakdown.

4.  The flame screen is of robust construction and is re-enforced to prevent breakdown due to water overfill, or debris in water. The screen is large, which minimizes pressure drop.

5.  The shield protects the closing mechanism from airborne pollutants such as dirt and spray painting.

6.  The heating solution for winterization (optional)

  • Ensures proper functioning in icing conditions down to -50°C
  • Is simple, robust and reliable

7.  ATEX and IECEx approved

8.  Can be ordered in corrosion resistant aluminum, galvanized steel, stainless steel or higher Duplex steel qualities.

9.  Fulfills the important requirements of DNV-GL Ship Rules Pt.3 Ch.3 Sec.6 Openings and closing appliances: I 308, 401, 402, 403 og 404

10.  Approved by all major classification societies:


Heating / Winterization

John Gjerde`s heating element ensures fully operational functions in icing conditions down to -50°C thanks to its location directly close to the guiding pin.

The heating solution is simple, robust and optimized to reduce the total power consumption by 80% compared to conventional

  • Self-limiting PTC heating system to ensure enough heat and to minimize power consumption by 80%. Turns on at < +5 deg C
  • 80% reduced installation cost, 95% less cables and 95% less MCB /sw board.
  • ATEX  and IECEx approved
  • All casted valves are prepared for heating and are easy to upgrade

HIDE – Options:

Below you have the several Hide options.

  • Flame/Bug/Rat screen
  • Heating/Winterization
  • Additional mud chamber preventing mud from entering the valve (See Mud Chamber).
  • Mounting alternatives: Flanged, threaded or welded
  • Painting
  • Vent through superstructure (see Hide 2)
  • Closing device for dry cargo (see Hide 3)
  • Vent through superstructure, self drained (see Hide 6)
  • Can be ordered in galvanized steel, stainless steel or higher Duplex steel qualities