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Resiliently Seated Valves

Systems Engineering Division (CG-ENG-3)

Each Code of Federal Regulation (CFR) cited below is updated annually in a free searchable database available from GPO Access.

A resiliently seated valve (RSV) is a valve in which the closure of the line is accomplished by resilient nonmetallic material instead of a metal to metal seat.  These valves are categorized and accepted by the U.S. Coast Guard based on intended service as per 46 CFR 56.20-15.

Positive Shutoff Valves:

Required Locations. Piping subject to internal head pressure from a tank containing oil must be fitted with positive shutoff valves located at the tank in accordance with 46 CFR 56.50-60(d).  Otherwise positive shutoff valves may be used in any location in lieu of a required Category A or Category B valve.

Standard Test Procedure: For Positive Shutoff Valves, the standard test procedure requires:

Category A Valves:

Required Locations. Except where positive shutoff valves are required, Category A valves are required in each of the following locations:

Standard Test Procedure: For Category A valves, the standard test procedure requires:

Vital Systems:

The term vital system is used in several places in U.S. regulations and other documents, sometimes without formal definition.  A system should be regarded as vital if it must start or continue working to protect the vessel, personnel, or the marine environment from serious harm.  Such systems generally include, but are not limited to, the following:

Once a system or a portion of the system has been designated as vital, the specific regulatory requirements should not be applied arbitrarily.  For example, while aluminum and other heat-sensitive materials should not be used in vital parts of systems without specific authorization, if the vital system is one that may not continue to function after a major fire, such as propulsion or steering, the use of some aluminum components that would not be damaged by minor fires may be authorized.  However, dry fire mains and dry foam mains, for example, must resist major fires while dry and then function properly later thus aluminum components should not be authorized in such systems.

The term vital has sometimes been used incorrectly to describe hazardous systems.  A hazardous system may or may not be considered vital.  For example, a high-pressure air system used only for tools and industrial machinery might contain a great deal of stored energy capable of injuring personnel or even damaging the ship if it failed violently.  However, this is not a vital system because it could be taken out of service at any time, even during a casualty or in a maneuvering situation, with no risk to personnel, vessels, or the marine environment.  Non-vital hazardous systems may still be subject to other regulations just not those specific to vital systems.

Valve Acceptance Procedures:

General Acceptance.  Valves are not issued a Certificate of Approval by the U.S. Coast Guard.  Instead, the Marine Safety Center (MSC) determines if a valve is suitable for the intended purpose during engineering plan review for each vessel/system.

Test Procedures.  There are three different methods that may be used to obtain acceptance by the MSC during plan review, with the flow rate performance test being the preferred method.  Manufacturers are responsible for forwarding the test results along with all related documentation to the MSC in Washington DC to demonstrate that the valve complies with 46 CFR 56.20-15.  The following are the only acceptable test methods for valves:

Category B Valves:

Valves that do not provide effective closure of the line, or that permit appreciable leakage from the valve when the resilient material is damaged or destroyed, are Category B valves.  Category B valves are not required to be tested and may be used in any location except where Category A or a Positive Shutoff Valve are otherwise required.  Category A valves that fail to meet the requirements for positive shutoff are considered Category B.

Contact the Systems Engineering Division (CG-ENG-3):

Commandant (CG-ENG-3)
U.S. Coast Guard
2703 Martin Luther King Jr. Ave. SE STOP 7509
Washington, D.C. 20593-7509
Tel: +1 (202) 372-1367

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Last Modified 9/10/2013