On March 13, 2007, Employee #1, a subcontractor, performed maintenance on commercial foodservice equipment. He was in the kitchen area of a single-story restaurant, attempting to locate the source of a refrigerant leak in an ice cream storage dipping cabinet. Employee #1 connected a Nitrogen cylinder to the dipping cabinet’s refrigeration system via a hose WITHOUT using a pressure reducing device, such as a pressure regulator or pressure relief valve. The cylinder’s internal pressure of approximately 2,200 psig was considerably in excess of the dipping cabinet’s maximum test pressure of approximately 150 psig. This disparity overpressurized the dipping cabinet’s refrigeration system and caused it to explode. The upper part of the compressor broke off and struck Employee #1 in the head, killing him.
Here are the requirements from ASME B31.3 leak test (e.g. pressure testing)…