Double Stem Seals vs Packing Nuts in Valves
Double stem seals are superior to packing nuts in durability, longevity and leak prevention in most applications, which is why Viega uses them in its 2-piece ProPress® and new MegaPress®G valves.
Packing nut designs consist of packed Teflon around the stem between the handle and ball of the valve. As the Teflon shifts or deteriorates, a leak path will form that will have to be corrected by tightening the packing nut. This creates additional work for installation, as well as continued maintenance.
Cutline: Valve with packing nut
There are a few cases when use of a packing nut is beneficial. Viega’s MegaPress® 3-piece ball valves utilize a packing nut to allow for replacement of the internal, wearable components during maintenance.
Why double stem seals are better than packing nuts Unlike packing nuts, which are used in many industry valves, the stem seals used in Viega valves will not deteriorate and leak. The double stem seals also eliminate the need to constantly tighten packing nuts, saving many hours on the front-end and back-end of installation. As those who’ve dealt with leaky valves can attest, a valve can be tightened only so many times before the packing can no longer hold the seal. At this point, the valve must be replaced.
Double EPDM seals between the handle and ball are standard on Viega's 2-piece valves. They are installed with a static seal, eliminating any wear and tear issues. EPDM is a synthetic, cured, all-purpose elastomer with excellent resistance to chemicals and other harsh environmental conditions. With operating temperatures from 0°F to 250°F, it is suitable for any type of water application, as well as compressed air and ketones. Check out why Viega professionals love the EPDM double seal on our new press valves.
Cutline: Viega valve with double stem seal
ProPress and MegaPress valves
We offer eight models of ProPress two-piece ball valves for potable and non-potable copper applications, as well as a ProPress automatic recirculation valve, check valve and butterfly valve. They are configured with a mix of connections, including press, female pipe thread and hose. In addition to valves, the ProPress system includes:
- Tools and accessories
Our new MegaPressG valves for fuel gas applications are available in ½" to 2". MegaPressG configurations include:
- No-stop couplings
- Reducing tees
- Reducing adapters
Both ProPress and MegaPressG valves include Smart Connect technology, which makes it easier to identify unpressed connections.
More information about Viega valves can be found here.