The Effectiveness of Pressure Safety Valves in Chemical Supply Systems to Prevent Fire, Explosion and Overpressure in the Korean Semiconductor Industry

Abstract

This study was conducted to review the safety and appropriateness of PSV (Pressure Safety Valve) installation in the supply tank, which is a pressure vessel included in supply systems dedicated to supplying the acid/alkaline substances used in the Korean semiconductor manufacturing process. Three aspects of design, risk assessment, and regulations were reviewed to determine if there is a source of pressure higher than the maximum allowable working pressure (MAWP) of the supply tank that could cause fires, explosions, and overpressure. In the case of the design review, all 17 overpressure scenarios described in API Standard 521, i.e., pressure-relieving and depressuring systems, were reviewed, and there was no overpressure scenario above the maximum allowable working pressure (MAWP). Then, the risk assessment, i.e., the Hazard and Operability Study (HAZOP) technique, was used, and as a result of reviewing all possible risk situations, we can state that there were no overpressure scenarios that can exceed the design pressure of the supply tank; thus, we decided that the installation of a PSV on top of the supply tank is unnecessary. Finally, accident prevention measures against overpressure, such as the KS B 6750-3 system design and the Korean Industrial Standard, were reviewed from a legal point of view. It was confirmed that the hazardous chemical supply system for the semiconductor industry designed in this study has several protective functions to prevent fires, explosions, and overpressure. As a result of reviewing the above three aspects, it can be said that there is no need to install a pressure safety valve in a pressure vessel storing hazardous chemicals.