We report on the design and development of a parallel frontal code HSL_MP43 for the numerical solution of the large sparse highly unsymmetric linear systems of equations that arise in industrial-scale chemical process engineering. HSL_MP43 has been developed for the mathematical software library HSL 2000 (http://www.cse.clrc.ac.uk/Activity/HSL). The main design goals for HSL_MP43 were: probability, ease of use, efficiency, arid flexibility. We discuss how each of these objectives is addressed within HSL_MP43 and illustrate the performance of the code using a range of large-scale problems from chemical process simulation and optimisation.