Safery Relief Valve for SCU - Marine application (410A)

Hi,

I need help to clarify if a safety Relief Valve is needed for a Self Contained unit using R410A.
After almost 30 years working with refrigeration systems, I have never encountered a system with no safety relief valve apart from some small hermetical fridges.

I have an SCU which will be installed in an unmanned sub station on board a ship.

SCU cooled (36°C LT cooling water)
20kg R410A,
Receiver approx 10L but not used, and isolated with a Valve on the liquid side.
(according to manufacturer the receiver can be used in conjunction with a portable recovery unit.
Plate heat exchanger for condenser.
External evaporator (DX) for air cooling.
Cooling capacity Approx 70kw.
CE approval on SCU.


According to DNV any refrigeration units below 100kw are not applicable to class rules, so manufacturer does not want to install a safety relief valve.

Surely this is not good engineering practice ? and is there a regulation i could use to push for a safety valve to be installed?

Regards