Staring with their first Safety Instrumented System (SIS) installation, have supported this major manufacturer for over 20 years. Utilized Layers of Protection Analysis (LOPA) to determine Safety Integrity Level (SIL) for each critical interlock function, completed SIL calculations based on the interlock conceptual design, and then documented the Safety Requirements Specification (SRS). Since the PHA was found deficient, site later requested PHA re-do. Extended PHA applications came later when the plant manager was promoted to the chemical division VP and the consultant was requested to also support facilities in Texas. Besides managing and facilitating up to four (4) concurrent PHAs, supported Texas site�s first LOPA, SIL, and SRS, as well as performing quantitative fault tree analysis (FTA) to complex ETT PVC reactor SIFs.