If you look critically at pp compression fitting, one thing is apparent... they are designed to inhibit the movement of the pipe outward from the fitting. However, they do a poor job preventing the pipe from turning within the fitting. To visualize this, take the example of the connection for a refrigerator icemaker.
Typically, a compression fitting is used to connect copper tubing to the icemaker. To prevent the thin 1/4" tubing from kinking or bending when the refrigerator is pushed back to the wall, an excess of tubing is normally "coiled" behind the refrigerator. This acts like a spring, expanding when the refrigerator is pulled out, and compressing when the fridge is pushed back.
A problem arises if the tubing is not solidly clamped to the rear of the refrigerator. Without this clamping, the tubing creates a rotational stress on the compression fitting as the fridge is moved, and can over time cause the tubing to rotate within the fitting, or even loosen the compression nut, causing a "stealth" leak behind the refrigerator. This can be a particularly nasty leak, because it can soak the floor with not evidence until the damage is severe... or until friendly, family-minded carpenter ants find the nice, damp wood!
The plastic ball valve is also one of our products, welcome to your come and purchase!