Water-related failures in commercial heating and cooling systems can be expensive, time-consuming and sometimes deadly. Modern water treatment chemical programs and application knowledge are more than sufficient to maintain these systems properly and prevent failures, yet failures continue to occur.
Experience has shown that in a large percentage of water-related equipment failures, the root cause failure analysis points to one or more of three factors: a) poor operating and maintenance practices; b) inadequate water treatment and service programs; and c) lack of facility management support for water system operations. This paper uses detailed case histories to illustrate these problems and demonstrate the need for a total management approach to water system operations.
INTRODUCTION
Rarely is there a single definable cause for a failure. A root cause failure analysis goes beyond the immediate cause – for example, oxygen pitting in boiler tubes. When did the pitting occur? What was the source of the oxygen? What happened to the oxygen scavenger? Was the deaerator working properly? What was the condition of the condensate? What were the boiler operating practices? Why was the problem not detected and corrected long before a failure occurred? What sequence of events, perhaps extending back several years, led to this specific failure? What can be learned from this experience to help prevent similar failures in the future?
Failures range from weeping threaded joints, or a loss of vacuum in a condenser, to major equipment failures, sometimes with personal injuries. A consultant usually becomes involved after the fact. Something bad has happened, and either the owner, the water treatment vendor, or perhaps an attorney, has hired a consultant. The consultant’s job is to investigate the problem, explain what happened and why, and offer recommendations. The tools the consultant has to work with include the failure itself, plant and vendor records, personal inspections and interviews, the technical literature, and his/her own knowledge and experience.
The two failure analyses presented in this paper were selected to illustrate how sequences of apparently unrelated problems led eventually to specific failures. The emphasis in the discussion is not so much on the failure itself as on the events leading to the failure and the interactions of management, operations and water treatment vendors at each location.