Valve boxes and curb boxes are underground devices that protect valves within water, wastewater and gas utility lines. They also permit access for valve operation.
Valve boxes and curb boxes telescope outwards and consist of upper and lower sections. The upper sections are made of steel pipe and are designed to telescope up or down within a base casting that is often made of iron. The upper sections are held in place by a clip ring at the top of the base, and differ in terms of maximum extension. Swaged lugs at the bottom of the upper section are designed to fit into a cast slot in the base, preventing the upper section from turning during the removal of the lid or pentagon plug. Typically, the pentagon plugs for valve boxes and curb boxes are made of cast brass.
Types of Valve Boxes and Curb Boxes
There are several different types of valve boxes and curb boxes. Two common categories are arch pattern curb boxes and Minneapolis curb boxes. Arch pattern, arch base, or Y-base curb boxes and accessories cover the curb stop, but are not connected mechanically. Using a cotter pin, the shut-off rod attaches to the T-head of the curb stop and is fixed in place. Minneapolis curb boxes have female threads that are machined into the bottom of a base which screws onto male threads. By threading the curb stop into the curb box, these curb boxes provide a unified valve and box assembly. They telescope up to one foot, and carry specifications for ball valve curb stops and plug type curb stops. Erie pattern or eclipse valve boxes and curb boxes are also commonly available.
Valve boxes and curb boxes are designed for water, sewer or gas-line applications and comply with standards such as ASTM A48, Class 25. Components include water lids, sewer lids, and gas lids; centering rings, rods, stops, and arches; anchor bolts, anchor nuts, and support rings; and Minnesota pattern valve support brackets. With curb boxes and accessories, standard lids include Erie pattern products, as well as lids that are tapped 1", 1.25", 1.5", and 2". Pentagon plugs are designed for use with ball valve curb stops or inverted plug-type curb stops. Bases are categorized as enlarged or standard. Valve boxes and curb boxes also include curb box keys, pentagon keys, fire sprinkler lids, irrigation lids, and reclaimed water lids.