Hazards associated with chemical processes can lead to accidents, which can be managed through process safety strategies. Inherent safety is a proactive tactic, capable of both identifying and minimizing the hazard. Available inherent safety assessment (ISA) methods focus on route selection only. Individual process equipment characteristics, especially the mechanical aspects are not reported for ISA. Subsequently, this paper presents a new technique for suitable material selection of process equipment at initial design stages. In inherently safer mechanical material (ISMM), process characteristics are coupled with the mechanical attributes for mechanical material selection of process equipment. The relative ranking of process equipment is used to highlight the critical process equipment that is more prone to leak. This risky process unit is further studied to select the suitable mechanical material. Two-fold mechanical compatibility criteria are established, which needs to be satisfied for material selection. If the proposed material is found unsuitable, inherent safety theme is used to propose the suitable material. The ISMM technique is verified by a case study of MMA-TBA process plant Hysys simulation. The technique is simple and identifies the crucial equipment in early design stages, which can help the design engineers to implement inherent safety at the basic design stage. © 2018 Institution of Chemical Engineers