This is not just another RMP General Duty Clause case. This case centers around a “critical utility” and how its FAILURE led to the release of a flammable gas and explosion. And the critical utility was the plant air system and the critical component was air dryer. The facility had recognized these systems as critical AND had the air dryer on an inspection schedule. Each shift, facility employees inspected the desiccant crystals in the air dryer system to ensure that the desiccant crystals are blue in color, which indicates that the air is dry. Employees then record the results on a checklist. The review of these records revealed that during the time period from January 22, 2014 until the time of the incident, area operators had noted the desiccant’s LACK OF blue color on the inspection checklist, but no actions were taken to address this condition. The presence of moisture in the lines in extremely cold temperatures led to the failure of the west flare stack’s valve to open due to a frozen air-line.