What is the consequence of over-tightening a fitting on a pipe?

Over-tightening a fitting on a pipe can lead to stretching of the fitting or the pipe material itself, resulting in a compromised joint. When excessive force is applied during tightening, it can deform the materials at the joint, leading to gaps that allow fluid to leak. This occurs because the materials may yield beyond their elastic limit, creating an irregular connection that is no longer able to form a reliable seal.

In contrast, while it might seem intuitive to think that over-tightening could eliminate leaks completely, this can actually increase the risk of leaks due to the damage caused by deformation. The wrench breaking is a potential concern, but it is not a direct consequence on the fitting or joint itself. Additionally, the overall length of the pipe does not typically decrease due to over-tightening; rather, the risk of failure in the joint increases, leading to potential leaks. Thus, the stretching of the fitting and resulting joint leak is the primary consequence to consider.