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Trade Press Release

Langh Ship steel products transport systems strengthen MacGREGOR portfolio


Pressurised hold system prevents hatch cover leaks

Suitable for newbuildings and existing cargo vessels, MacGREGOR's patented hold overpressure system solves hatch leakage problems on board and ensures a ship operational efficiency and safety

MacGREGOR's patented hold overpressure system is a way of maximising the weathertightness of hatch covers. After the covers have been closed and cleated, and all other openings including non-return drainage valves have been shut, the cargo hold is pressurised to a slightly higher pressure than atmospheric, to a maximum of 0.04 bar.

All leaks caused by, for example, old sealing systems, or wear and tear in stoppers, can be prevented by pressurising the hold. The positive pressure is enough to ensure weathertightness even in the case of several small leaks. Pressure in the hold is maintained by fans throughout the voyage a relief valve ensures that the pressure is kept at the correct level and a pressure gauge is fitted on the bridge. The system works with CAT-profile, Flexseal and sponge seals.

Fittings needed for the hold overpressure system are:

  • air fans (capacity depends on the hold size)
  • shut-off valves for non-return drainage valves
  • pressure relief valve to ensure the correct pressure level in hold
  • pressure gauge for checking the correct pressure level.


  • leaks can be avoided by pressurising the hold
  • fewer cargo claims and thus lower insurance premiums
  • easy testing of weathertighteness, particularly with MacGREGOR's ultrasonic Sherlog system
  • suitable for newbuildings and existing vessels
  • easy to operate.

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