Issue link: http://read.uberflip.com/i/1051049
USICERINKS.COM NOVEMBER.DECEMBER.2018 / 31 of safety risks associated with refrigeration systems. The investigation identified three areas where evidence indicates causal and contributing factors leading to the incident and the subsequent impact to the arena and surrounding community: I. Failure of refrigeration system equipment II. Operational decisions that contributed to the incident III. Impact of inadequate ventilation and discharge systems following the incident I. FAILURE OF REFRIGERATION SYSTEM EQUIPMENT The investigation found that the ammonia release was initiated by a small hole within the curling system brine chiller caused by corrosion pitting at a carbon-steel tube welded seam. The corrosion process typically progresses with the operational use and age of equipment and can accelerate in areas containing defects that promote pitting. An estimated typical operational life-cycle of 20-25 years was identified for this type of chiller which was manufactured 31 years prior to the incident. The investigation did not find documentation indicating the exact start date of active service for the chiller. Ammonia was detected within the brine system during maintenance and brine testing conducted as part of routine shut down procedures at the conclusion of the 2016/2017 operating season. After a summer shut down period, the curling refrigeration system was re-started on October 16, 2017. Ammonia released through the brine system led to an ammonia alarm at 3:53 a.m. on October 17, 2017. In response to the ammonia leak, the brine system and curling chiller were isolated and the refrigeration and brine system were shut down. This impeded brine expansion and ventilation, as ammonia continued to leak into the brine over a five hour period. As the leak continued, the concentration of ammonia would have become higher close to the chiller and the hole in the tube. The likely effect within the brine system near the chiller was: an ammonia saturated volume of brine; a temperature increase from chemical reaction and heat absorption from the room; elevated pressure within the brine system and chiller; and a displaced volume of brine from ammonia being added to the saturated solution. A brine system pipe segment was joined at two locations near the chiller Tube sheet Brine out Brine in Tube sheet Ammonia in Ammonia out Ammonia out Tubes Shell Return head Inlet/outlet head , Figure 1: Generic diagram of a two-pass flooded chiller similar to that used at the Fernie Memorial Arena.