Fugitive emissions are no laughing matter, and valves are usually the culprit. Even if they don't get you into trouble with your neighbors or the EPA, they could prove costly. We'll explain the problem so you know whether you're at risk, and we'll discuss what to do if you are.
Poor quality valves, especially those that are used regularly but not looked after, will eventually start to leak. Usually they leak along the shaft or “stem” linking the handle to the ball, butterfly, or diaphragm.
That stem is surrounded by packing material. This stops the gas or liquid being controlled from escaping. (Leaks are much more likely with gas.)
In a large industrial valve, there's a housing or “bonnet” around the stem that's filled with packing. In smaller valves, the packing is incorporated into the valve body.
When a valve is operated regularly, the packing around the stem starts to wear. If the stem gets dirty, turning it can push those particles down into the packing and make it wear faster.
Leaks from valves are termed “fugitive emissions,” which the EPA defines as “emissions which could not reasonably pass through a stack, chimney, vent, or other functionally equivalent opening.”
Know if you're at risk
The main problem is with gases, especially those that could be harmful. Chlorine is one example where a fugitive emission could injure anyone working or living nearby. A valve has to be in bad condition to leak liquid, but if it was in a refinery or chemical plant, it could evaporate and become a hazard.
Something like this will get you into trouble with the EPA or your state Department of Environmental Quality. But even if the leak isn't hazardous, it's going to cost you money. That's simply because any leak is wasted product. It's been estimated that 3.6 trillion cubic feet of natural gas leaks into the atmosphere around the globe every year.
Requirements if fugitive emissions are a risk
Chemical plants, particularly oil and gas facilities, can't turn a blind eye to the problem. First, they should run a Leak Detection and Repair Program. The LDAR Program involves someone going around with an electronic “sniffer” to check for leaks. The actual sniffing can't be done on a casual basis either. The EPA expects organizations to follow “Method 21” when checking for fugitive emissions. This defines the exact way in which the testing must be done.
Preventing valve leaks
Three steps can reduce your risk of problems. First, don't skimp on valves: buy quality products. Second, conduct regular valve maintenance. Keep the stems clean and tighten the bonnet or nut on the top of the valve if necessary. Third, if you are dealing with hazardous gases, look for valves designated as low-emission (Low-E) or using Low-E packing.