Rupture disc in piping

As close as practical to the equipment or line section it protects. A short, direct inlet keeps the pressure drop during relief low. It also means the disc sees nearly the same pressure as the protected equipment. The inlet should be at least as large as the disc connection. Straight pipe upstream of the disc gives an even pressure distribution across the membrane. Positions directly after elbows, pumps, compressors or fast-acting valves are best avoided. The discharge side must lead the medium to a safe location. We can review a proposed location when you send us a sketch or isometric.

Straight pipe gives the flow time to settle before it reaches the disc. Elbows, tees and valves create turbulence and uneven pressure across the membrane. Pumps and compressors add pulsation that loads the disc with every cycle. Over time that cycling can cause fatigue and an opening below the marked burst pressure. Metal discs mounted directly between flanges are intended for systems with straight pipe sections. Where straight pipe is not available, a holder and a disc type that resists cycling help. Reverse buckling designs offer better resistance to pressure cycles. Placement and selection work together here.

The disc reacts to the differential pressure over the membrane. Superimposed back pressure on the outlet side raises the upstream pressure needed to burst the disc. Built-up back pressure during flow reduces the capacity of the relief path. If the outlet pressure exceeds the process pressure, the disc is loaded from the wrong side. That can damage a disc that is not designed for it. Vacuum support or a vacuum suitable disc prevents this. The expected back pressure must be part of the specification from the start. Please include it in every request you send us.

The discharge line must lead the medium to a safe location. Toxic, flammable or hot media usually go to a closed system such as a knock-out drum or flare. Vents to atmosphere must point away from walkways, platforms and air intakes. The piping and supports must withstand the reaction force when the disc opens. Liquid should not collect on the outlet side of the disc. A discharge line that drains away from the disc avoids static loads and freezing. The outlet should keep rain out without restricting flow. We raise these points whenever we review a relief path.

Yes, and it is a very common combination. The disc protects the valve from corrosive or fouling media and prevents seat leakage. The valve limits the loss of medium after the disc opens and can reclose. The disc and valve are usually mounted close together. The space between them must be monitored for pressure build-up. A pinhole leak can raise that pressure and make the disc open later than intended. A pressure indicator, tell-tale or burst detection sensor in the interspace solves this. We supply the disc and holder for such combinations.

It depends on the conditions in the piping. Metal discs can be mounted directly between flanges in systems with straight pipe sections. Graphite discs are often installed directly between ANSI or DIN flanges. For pulsating pressure, cyclic loading or critical positions, a holder is generally the better choice. A holder gives reproducible clamping and protects the disc during installation. It also allows detection to be integrated and improves spacing to other safety devices. After an opening, the holder stays in the line and only a new disc goes in. We advise on the option that suits your line.

In a disc and valve combination, the two are mounted close together by design. For separate devices, the spacing should allow each to work without disturbing the other. Devices mounted too close together can interfere during relief and are harder to inspect and replace. Access for maintenance is a practical concern that is easily overlooked. A holder helps create better distance to other safety equipment. Detection equipment also needs space for cabling and connections. The overall layout should be reviewed together with the piping design. We are happy to look at the arrangement with you.

Start with the medium and its composition. Add the operating pressure including peaks, the required burst pressure and the temperatures. Include the expected back pressure on the outlet side and any vacuum conditions. State the connection standard and nominal size. A sketch or isometric of the inlet and discharge line is very helpful. Mention nearby sources of pulsation such as pumps, compressors or control valves. With that information we can advise on disc type, holder and detection. Send your data to sales@dutchvalvevision.com and we will get back to you.