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VCO Swagelok for 2000 psi hydrogen

VCO Swagelok for 2000 psi hydrogen

VCO Swagelok for 2000 psi hydrogen

(OP)
Folks, can anyone comment on the suitability of VCO face seal fittings (instead of Swagelok) for high pressure hydrogen?  I know very little about VCO and can't find any reference to swagelok or VCO in ASME B31.3.  There is information on www.swagelok.com, however I am interested in other (non swagelok) comments as to the suitability of VCO for high pressure flammable gas.

The H2 is fed to a control panel at 138 barg/2000 psi cylinder pressure, and let down through a regulator to 10 barg/150 psig.  It is proposed to modify the existing setup to VCO (or perhaps Swagelok) type valves and pressure gauges to facilitate maintanance on this equipment which is mounted onto the control panel.

I realise fully welded is safer, however the current fully welded design is very impractical with regards to valve/equipment maintenance.  (And if hydrogen becomes unavailable due to valve failure, this poses a different safety risk downstream of the panel.)  The panel is outdoors, in a remote location and any electrical equipment in the vicinity is Ex rated.

RE: VCO Swagelok for 2000 psi hydrogen

Even the largest VCO fittings are good to 2300 psig at room temperature.

We use ordinary 2-ferrule Swagelok compression fittings routinely to beyond 2000 psig with hydrogen without problems.  We use VCO in these services where straight line pull-out is required (i.e. such as when used in a panel).

The fitting is not firesafe due to the o-ring seal.  VCR (the metal gasket version) should be closer to firesafe.  If your master shut-off valve on the supply of hydrogen to this panel is firesafe with a fusible link, the issue is probably moot, but you'll have to decide that yourself based on your circumstances.

 

RE: VCO Swagelok for 2000 psi hydrogen

20 yr ago ,We had an H2 system ,much as you describe; a couple systems were tested and we found Swagelok to be most reliable. Swageloks were also required for serious autoclaves, to 20,000 psi.

RE: VCO Swagelok for 2000 psi hydrogen

You would be using cone and thread construction at 20,000 psig (i.e. Autoclave Engineers, Sno-Trik, Butech, HiP etc.), not Swagelok 2-ferrule compression fittings or even their new medium pressure fittings.

RE: VCO Swagelok for 2000 psi hydrogen

I've used all of the above on hydrogen systems without any issues.  I would stick with the VCR fitting over the VCO to avoid compatibility and temperature concerns, but the regular compression Swagelok fitting are pretty much our standard.

Dan

www.eltronresearch.com
Dan's Blog

RE: VCO Swagelok for 2000 psi hydrogen

Molten; you caught me. We had several autoclaves ,the lower pressure units (5000 psi ?) had swageloks and the very high pressure units were Autoclave engineer.

RE: VCO Swagelok for 2000 psi hydrogen

(OP)
Thanks moltenmetal, blacksmith & Dan for the useful responses.

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