When it comes time for maintenance, the cover on a PVC drainage pipe valve can be hard to get off after years of use. The cover is in the valve box, subject to changes in soil, moisture and temperature. Over time sediment fills the space between the cover and the riser and the plastic can fuse to the surrounding surface. Using a screwdriver or a pry bar to get the cover off will usually crack the cover, or worse yet, damage the riser below.
Lid-Sticking
In the case of a PVC drainage pipe valve cover assembly , the cover is not usually glued on . It sits in the valve box opening and is held in place by friction, gravity, or a snap-fit. Over years of service, fine soil particles and organic debris find their way into the seam between the cover and the box. Water brings in these particles and when the soil dries it acts like a weak cement. The plastic cover and plastic box also swell and shrink with the temperature changes and after enough cycles the two surfaces can bond tightly. Older installations may have the cover painted over or surrounded by landscaping material that has compacted over the years.
A Method That Often Works
The safest thing is to break the cover rather than to pry at it. The important part is the riser below . The valve cover on a PVC drainage pipe is cheap to replace . If you pry the cover too hard, the screwdriver or pry bar can slip and crack the riser. The riser is embedded and much harder to fix. Deliberately breaking the cover, with hammer and chisel or a small pry bar applied to the center of the cover, concentrates force where it does no harm. When the cover is broken up the pieces come away and the opening to the riser is exposed for inspection or cleaning.
Prior to removing the cover, ensure that a replacement of the correct diameter and marking is at hand. Standard valve box covers are available in sizes such as 6-inch and 10-inch round, and are stamped with labels such as "ICV" for irrigation control valve or "SEWER" for sanitary cleanouts. Order the replacement first so the system isn't exposed to debris while you wait for the part to arrive
When the Cover is Removed
Remove the PVC drainage pipe valve cover and check the riser and valve below it. Sediment that built up around the cover may also have entered the riser. If the valve is an irrigation control valve, check that the solenoid and wiring are not damaged. If the access point is a sewer cleanout, make sure the plug or cap below it is tight. The new cover should be easy to put on. If not, the riser opening may have debris or damage that needs to be addressed before the cover is replaced.