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Sight Glass Check Valve

Sight Glass Check Valve

Sight Glass Check Valve

I'm not sure if this is the best forum to put this in, but the sight glasses in question are going on pressure vessels, so here goes...

This is concerning sight glasses on two-phase and three-phase separators for use in the oil field (up to 250 psi). Standard gauge cocks used for mounting sight glasses have a ball check valve in them, so if the glass breaks, the contents of the vessel don't go spewing out. The problem we're seeing with this setup is that the ball check valve, (and the needle valve as well), will quickly become clogged and inoperable, rendering the sight glass useless. In some locations, sight glasses never function, even on initial startup. The emulsion is too waxy and the cold metal of the gauge cock solidifies it so fast that the glass never sees liquid.

The proposed solution is to ditch the gauge cock completely (ball check and needle valve), and just leave standard ball valves between the vessel and the glass. The ball valves will be closed when no one is on site, and only used to check levels when an operator is there to supervise - this assumes they remember to close the ball valves when finished. So the main concerns I have are with the safety and ethics of not having that check valve. If you unknowingly had compromised glass, opening the valve could cause a very dangerous situation. Also, if a ball valve was left open and unsupervised, you could have an environmentally unfriendly situation develop very quickly.

Has anyone seen a setup like this before?
Is there an alternative safety/environmental protection I could use in lieu of the ball check?
Does OSHA or the EPA have anything to say about sight glass mounting/construction?

I'm continuing with my own research on this. I just wanted to see if this community had anything to contribute. Thanks in advance for you feedback!

RE: Sight Glass Check Valve

Yeah, I've seen sightglasses without ball-checks, the idea being that they basically never actually work anyways (which, they do if they're operated properly, but that's pretty rare). I don't really favor it, having seen what happens when a sightglass blows (CHPS in a gasoil hydrotreater, was a truly shocking amount of flow, through a ball-check that wasn't backseated all the way). Can't imagine if someone had been in front of the thing at the time...

There are a lot of really good mag-gauges out there now, might be worth a look.

RE: Sight Glass Check Valve


Thanks for your reply and for pointing me towards mag-gauges. I do think that is a better solution, and I will run it past a few customers. However, I think I know what they'll say - keep the cost down. Especially with the way oil prices are now. People aren't looking to get fancier.

RE: Sight Glass Check Valve

Quote (FoxRox)

Especially with the way oil prices are now. People aren't looking to get fancier.

Maybe, and this will depend on who in the owner's organization is talking. Project management: Cheap is good! Technical, Ops, and Reliability management: Cost is something to consider, but safer and more reliable can easily trump cost. Certainly my company has reduced its capital spending, but the projects which I am seeing going forward have not pushed to cut equipment cost at the expense of long term reliability and safety.

And hey, oil went up a bit today!

RE: Sight Glass Check Valve

Yes, we have seen the same. The industry is finding innovative ways to process more wells with less equipment. Reliability and safety have not been compromised. If anything, they have improved because we're building more of the finished product on the manufacturing side instead of roustabout crews building the majority of systems on the fly. But I don't think this particular customer sees the sight glasses as a safety issue. They just need something that will function and be cost effective with their waxy emulsion. Mag-gauges might be the answer, but I'm afraid it will be cost-prohibitive. Competition is tough, and margins are shrinking. Like I said, I will be running the idea past my bosses and customers. That decision is above my pay grade. :)

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