What Is A Storm Valve?
Storm valves can be found in every day marine systems. Normally, they are situated in sanitary piping systems that have a ship-side exit. These valves have the ability to prevent seawater from entering the system during rough sea conditions. Additionally, these valves, also called “scupper valves” or “discharge check” valves can be found and used on overboard discharge lines to remove sanitary wastes or wastewater.
A storm valve is essentially a swing-check valve, with a closing device. The closing device helps control flow with either a manual wheel or actuated system. The valve functions quite simply, and offers either fluid isolation or non-return.
How Does A Storm Valve Work?
When working with a storm valve, you will notice that there are two openings – the inlet and the outlet. Quite simply, fluid flows in through the inlet and out through the outlet. Inside the valve is a flap which is attached to a counter weight, and a locking block. The locking block is the piece of the valve that is controlled and operated by the external hand wheel or actuator. The purpose of the locking block is to hold the flap in place which ultimately prevents the flow of fluid.
Once flow begins, the operator must choose whether to open the locking block, or keep it closed. If the locking block is closed, the fluid will stay out of the valve. If the locking block is opened by the operator, fluid can flow freely through the flap. The pressure of the fluid will release the flap, allowing it to travel through the outlet in one direction. When flow stops, the flap will automatically return to its closed position.
Regardless of whether or not the locking block is in place, if flow comes through the outlet, the back flow will not be able to enter the valve due to the counterweight. This feature is identical to that of a check valve where back flow is prevented so that it will not contaminate the system. When the handle is lowered, the locking block will again secure the flap in its close position. The secured flap isolates the pipe for maintenance if necessary.
Storm Valve Tests
The most beneficial test to perform on your storm valve is a hydrostatic test. In a hydrostatic test, your storm valve will be tested for strength and leaks. To perform a hydrostatic pressure test on your storm valve, view this video and follow the steps below.
1. Open valve to a fully open position.
2. Attach gauged disk to flange (outlet)
3. Fill valve cavity with water
4. Block off flange with a blank disk (inlet)
5. Raise pressure to 723 KPA for 3 minutes
6. Check body for leaks
7. Release pressure
8. Lower handle to fully closed position
9. Remove blank disk
10. Vacate valve cavity of water. Now only the inside of the valve (where backflow would potentially be) is only filled with water.
11. Raise pressure to 482 KPA for 1 minute
12. Check seat for leaks
13. Release Pressure
14. Raise handle
15. Raise pressure to 482 KPA for 1 minute
16. Check seat for leaks
17. Release Pressure
18. Remove gauged disk from flange.
19. Lower handle
The standard body and seat test is performed on this valve. However, the seat test is conducted as two separate tests with the handle raised and lowered. It is important to note that due to the purpose of this valve the pressures are not rated as high as other valves.