The question of whether to remove the Sharkbite plastic insert for copper fittings is indeed more complex than it first appears. From my understanding and experience in plumbing, this small component plays an important role but also raises several concerns about system integrity and longevity.

To clarify, the Sharkbite fittings come with a plastic liner or insert designed to reduce friction and protect the copper pipe from direct contact with the brass of the fitting. This plastic insert essentially acts as a barrier that prevents corrosion between dissimilar metals, which can significantly extend the life of the connection. In many cases, the manufacturer explicitly states that the plastic insert should remain in place during installation, especially when connecting copper pipes, as it helps maintain a secure, watertight seal.

If you were to remove the plastic insert, you might risk exposing the copper pipe to brass components directly, which could potentially lead to galvanic corrosion over time. This is particularly true in areas with aggressive water chemistry or high mineral content. Such corrosion could reduce the lifespan of the fitting and increase the chances of leaks. Moreover, the plastic insert contributes to stabilizing the pipe inside the fitting, which can improve flow by maintaining a smooth surface and minimizing turbulence.

Regarding flow rate, while the plastic insert does reduce the internal diameter slightly, the effect is minimal and generally negligible compared to the benefits of corrosion protection and leak prevention. The integrity and durability advantages far outweigh any slight reduction in flow capacity.

When it comes to expert opinions, many seasoned plumbers agree with leaving the insert intact because removing it can complicate the installation and does not provide any tangible benefit. Some plumbers might remove it if they feel the insert is damaged or if they are dealing with unusual pipe conditions, but this is typically on a case-by-case basis.

Temperature fluctuations and varying climatic conditions don’t seem to adversely impact the plastic insert in typical residential or commercial installations. The materials used are designed to withstand these stresses, ensuring a long-lasting connection.

Compatibility-wise, Sharkbite fittings and their inserts are engineered specifically for certain pipe types and sizes. It’s crucial to follow manufacturer guidelines because the insert contributes to the overall system design and performance.

In conclusion, the thoughtful approach is to adhere to manufacturer instructions and keep the plastic insert in place when installing Sharkbite fittings on copper pipes. Removing it without good cause can jeopardize the system’s durability, increase leakage risks, and potentially lead to premature failure. Thus, preserving this small insert is often a best practice supported by both empirical evidence and professional consensus.