This study investigates the effects of harsh environments, including Steam in Place (SIP) and thermocycling, on diaphragm valves. Seals, typically made from Polytetrafluoroethylene (PTFE) or Ethylene Propylene Diene Terpolymer (EPDM), regulate the flow of drug products in pharmaceutical plants. These seals represent the weakest points in the production process and are the most likely component to fail. Limited research on the degradation of these components exists, resulting in time-based preventative maintenance procedures across the industry. PTFE and EPDM seals are, therefore, replaced regardless of their condition. These time-based preventative maintenance programmes contribute to manufacturing downtime, unnecessary waste and increased costs. This research examines the degradation characteristics of PTFE and EPDM diaphragms to identify precursors to failure, facilitating a shift from time-based to condition-based maintenance. The research was divided into two phases. Firstly, a 'cradle to grave’ degradation path was determined for these advanced materials by studying changes in material properties under challenging conditions. Diaphragms were subjected to 500 industry-representative Steam-In-Place cycles using a bespoke test rig. A test regime based on the American Society of Mechanical Engineers Bioprocessing Equipment (ASME-BPE) Standard was adopted. Following exposure, diaphragms were analysed using material characterisation techniques to assess the impact of SIP cycles on the diaphragm materials. First, seal and shell tests determined whether the diaphragms performed as intended. The second set of tests determined the condition of the diaphragms using visual and microscopic inspections. Degradation features such as material flow, surface creasing, discolouration, and deformation were identified. A third set of tests focused on the material properties of the diaphragms, including flexibility and hardness.