Maximum Allowable Relief Valve Setting (MARVS) – Definition and Pronunciation

Examples of MARVS

Pressure vessels or vessels within which Maximum Allowable Relief Valve Settings (MARVS) can never be achieved require none of the foregoing. For ships built between 1976 and 1980 the above applies, except that pressure vessels of greater than 200 m³ are no longer exempt from the alarm/shutdown requirements.

From “Guidelines for Automatic Cargo Tank Overfill Protection Aboard Gas Carriers”.

For cargo tanks with a MARVS not exceeding 0,7 bar gauge, all liquid and vapour connections, except safety relief valves and liquid level gauging devices, should have shutoff valves located as close to the tank as practicable.

From “Philosophy and general requirements in the gas industry”.

Isolating valves for cargo tanks must be provided in accordance with Gas Codes. Where cargo tanks have a MARVS greater than 0,7 barg (Type “C” tanks), the principal liquid and vapour connections on the tank dome (except relief valve connections) should be fitted with a double valve arrangement.

From “Basic Knowledge of Tankers”.