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How to Use MegaPress Fittings for Steam

April 13, 2021 Viega
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We get a lot of questions about using MegaPress and ProPress in steam applications so we thought we’d address some of the most common ones. While both MegaPress and ProPress are approved for use in low-pressure applications, there are differences in how they should be used.

Sealing elements to look for

Viega offers two types of factory-installed sealing elements in its MegaPress carbon steel fittings for steam pipes: EPDM and FKM.

Fittings with an EPDM sealing element are marked with a green dot and are approved for residential applications up to 5 psi or approximately 227°F on a steam saturation chart.

Fittings with an FKM sealing element are marked with a white dot and are approved for low pressure applications up to 15 psi or approximately 250°F on a steam saturation chart.

Is steel or copper better for steam applications?

There is a bias against using copper piping in steam applications. The reason is that steam moving through the system at a high speed, coupled with constant temperature fluctuations between cycles, can cause the pipe to expand and contract. This torsion on soldered joints can cause them to leak.

However, ProPress copper fittings are better able to absorb the torsion and can even act as swing joints in the system. So ProPress copper fittings are a better option for steam systems than soldered copper fittings.

That said, we do recommend steel fittings as they are stronger.

MegaPress and schedule 80

Many steam systems use schedule 40 pipe for distribution and schedule 80 pipe for condensate return. Here’s why: Condensate piping is used to remove condensate from steam-heated vessels, ideally for recovery and re-use in boiler feedwater. Because condensate can contain carbonic acid and other corrosive elements, condensate piping is susceptible to corrosion and pinhole leaks. That’s why stainless steel is the preferred material and will deliver a longer life.

However, if less expensive carbon steel piping is chosen, schedule 80 pipe should be used because its thicker walls will prolong the life of the pipe.

MegaPress fittings are designed for schedule 5 to schedule 40 pipe. Steam condensate return piping with MegaPress carbon steel Is not recommended for use with schedule 80. MegaPress stainless is preferred in those situations.

Some steam systems will mix materials, using carbon steel for distribution and stainless steel for condensate return. In those systems, MegaPress fittings can be used with steam traps to make the transition from carbon steel to stainless steel. A MegaPress carbon fitting is used at the steam trap intake while a MegaPress stainless fitting is used for the outflow.

As anyone who’s ever done it can tell you, steam fitting is tricky. Using MegaPress and ProPress fittings with a single tooling platform can simplify things while delivering safe, secure and long-lasting connections.

Here’s an example of MegaPress being used for steam in a Brooklyn apartment complex.

We also have this video series available:

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