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 the Government Publishing Office.
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). Positive shutoff valves may be used in any location in lieu of a required Category A or Category B valve.
For Positive Shutoff Valves, the closed valve must pass less than 10 ml/hr (0.34 fluid oz/hr) of liquid, or less than 3 l/hr (0.11 cubic ft/hr) of gas per inch nominal pipe size through the line at full rated pressure after being subjected to the fire test requirements of API 607 (incorporated by reference; see § 56.01- 2). Packing material must be fire resistant.
Category A Valves:
Required Locations. Except where positive shutoff valves are required, Category A valves are required in each of the following locations:
- Valves at vital piping system manifolds;
- Isolation valves in cross-connects between two piping systems, at least one of which is a vital system, where failure of the valve in a fire would prevent the vital system(s) from functioning as designed;
- Valves providing closure for any opening in the shell of the vessel.
Category A valves must mee the fire test and leakage requirements of API 607.
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:
- Propulsion and necessary auxiliaries;
- Ship's service and emergency electrical generation and necessary auxiliaries;
- Steering;
- Firefighting;
- Bilge pumping;
- Cargo containment 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 catastrophically failed. 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.
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. Fire test for soft-seated quarter-turn valves using the procedures in American Petroleum Institute (API) standard 607. 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.
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.
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