The following lessons learned is an example of an industry loss study that determined that instruments in critical service should require routine maintenance and be provided with regular monitoring.

  1. Freeze-up of field-traced instrument in critical service for steam boiler drum level resulted in error to boiler controls which caused a boiler shutdown, which in-turn caused a total plant shutdown. The instrument was a fairly old installation in a moderate climate facility. An abnormal deep freeze resulted in temperatures that were beyond the system performance due to deterioration of the thermal insulation.
  2. Major freeze-up of 8" sanitary water header prevented water supply to safety shower units in process area. The unavailability of the safety showers resulted in curtailment of production in the operation that involved EHS chemicals. The tracer was operating normally, but a 3-foot section of thermal insulation had been removed in advance of planned work on the pipe. No alarms would have picked up this problem unless a temperature sensor was at the actual location. This lesson learned suggests the need to walk down traced pipelines in anticipation of freezing conditions recognizing that there may be recent activity that could result in freeze-ups.