The U.S. Navy has used galvanized steel ducting in Surface Ship ventilation systems for many years. Overall performance of this material in service has been acceptable, but excessive corrosion has been observed at weather openings and at locations where water collects. The corrosion observed could be attributed to design problems, such as improper placement of weather intakes and lack of low point drains, or to use of a ducting material which is incompatible with the service environment. Besides the cost associated with ducting replacements, seawater ingestion and duct corrosion can cause personnel hazards fromprojected debris and electrical arcs at switchboards. This paper discusses the various configurations and design issues considered in recent corrosion control evaluations of these systems. The benefits and problems associated with material options including stainless steels, textiles, and composites, is discussed. A cost benefit analysis for some of these options is included.
Millions of dollars are spent each year by the operational Navy to maintain shipboard ventilation systems, and much of this cost is a direct result of corrosion. In fact, the Navy has reorgnize-dventilation system corrosion as one of their top maintenance burdens. Recognizing that this and other maintenance burdens are a significant drain on fun@ the Naval Sea Systems Command has pursued the concept of engineering for reduced maintenance. As the Navy?s budget has decreased, this concept has received greater attention. This paper will focus on cost reduction by engineering for reduced maintenance for Surface Ship ventilation system ducting.
The primary material of construction for ventilation ducting on Navy ships for many years has been galvanized steel.(]) Overall, this material has performed well, but, corrosion performance has been poor for applications at weather openings and at locations where water collects. As a result, on average, partial ducting replacements are necessary every seven years. An additional consequence is that projected corrosion products can cause personnel hazards and electrical arcing at switchboards. Therefore, the desire to fix the corrosion problem is motivated by more than cost savings.
