A customer has asked about a lube fitting on the valve body for use as meter riser valves on natural gas.

One of the key advantages of a ball valve over older types (such as conical plug valves, which are the traditional valve used for gas meter sets) is that the ball valve seals absolutely bubble-tight without any sealant or lubricant being required. The reason for this is that the geometry of a ball valve allows the ball to “float” and therefor find its own center. That means the spherical surface of the ball is in perfect conformance with the circular shape of the downstream Teflon seat. The contact pressure between the ball and the seat is uniform, all the way around the sealing circle.

Such a self centering feature is not possible with a conical plug valve. A tiny difference in the cone angles of the plug and the mating female cone in the body can make the plug and body lose contact with eachother, either at the top of the plug or at the bottom. This problem has traditionally been overcome by injecting a lubricant/sealant into the body of the plug valve to fill up the small opening between the body and plug.

Of course this lubricant must be replaced occasionally in order to keep it fluid and to fill the leak spaces. That is the reason for the grease nipple on the stem or on the side of the body of traditional conical plugs. But Teflon-seated ball valves need no such periodic maintenance, and therefore they have no such grease fitting.

I hope this will help you explain to your customer why we don’t have grease fittings on our BONOMI INDUSTRIES SRL ball valves.