Cross-linked polyethylene (PEX-a) pipes have been quickly replacing metal piping in home and industrial applications due their cost-effective manufacturing process, ease of installation, and long projected lifetimes. However, PEX-a pipes are not immune to oxidative degradation from their environment while in-use, creating the opportunity for premature failure. Therefore, understanding the degradation process is critical to helping extend lifetimes and prevent expensive failures. We have developed several experimental protocols to accelerate the ageing process in-house in our efforts towards this goal, isolating the effects from various environmental stresses present during in-service conditions. By conducting FTIR microscopy measurements on unused/virgin pipes, as well as both in-service and in-house aged pipes, we have found several key indicators of an aged pipe that play a role in pipe failure. Principal component analysis (PCA) was conducted to identify characteristics of PEX-a pipes subjected to these various ageing environments.