Journal of Safety and Environment

Traditional hazard and operability (HAZOP) analysis relies heavily on expert judgment and lacks quantitative evidence when evaluating structural risks in shell-and-tube heat exchangers， often resulting in ambiguous and experience-dependent consequence descriptions. To address this limitation， this study proposes a systematic methodology that integrates steady-state fluid–thermal–structural sequential coupling simulations into the HAZOP framework to enable quantitative， mechanics-based risk assessment of structural integrity. A detailed three-dimensional numerical model of a fixed tube-sheet heat exchanger is constructed using the ANSYS Workbench platform， incorporating realistic geometric features and temperature-dependent material properties of 304 stainless steel. Steady-state computational fluid dynamics (CFD) simulations are first conducted to solve the Reynolds-averaged Navier–Stokes equations with the shear stress transport (SST) k–ω turbulence model， thereby obtaining the flow field and conjugate heat transfer temperature distributions under both nominal and deviation conditions. The resulting temperature and pressure fields are subsequently transferred as thermal and mechanical loads to a finite element structural model， where thermoelastic equilibrium equations are solved to determine equivalent stress distributions and total deformation. A dedicated risk assessment matrix is established by integrating the computed safety factor—defined as the ratio of material yield strength to maximum equivalent stress—with a region-specific sensitivity classification that distinguishes primary， secondary， and peak stress zones in accordance with pressure vessel design codes. Eight deviation scenarios are designed based on HAZOP guidewords， encompassing variations in cold and hot fluid mass flow rates (0.7–2.8 kg/s) and inlet temperatures (0–100 ℃). Simulation results demonstrate that temperature-induced deviations exert the most pronounced influence on structural integrity. Notably， the cold fluid inlet at 0 ℃ yields a maximum equivalent stress of 274 MPa and a safety factor of 0.8， corresponding to an extremely high risk level， while a hot fluid inlet at 100 ℃ results in 242 MPa and a safety factor of 0.91. In contrast， flow rate deviations induce comparatively moderate stress variations (102–177 MPa) and lower risk rankings. The proposed methodology not only aligns closely with empirical engineering judgment but also transforms qualitative HAZOP consequence descriptions into explicit， data-driven risk classifications， thereby providing robust， quantitative support for risk-based inspection planning and proactive safety management of shell-and-tube heat exchangers.