Refurbishment of packed tubesheets utilizing plastic ferrules embedded in epoxy cladding

Retubing a Type 316 Stainless tubesheet of the packed tube joint design with more noble super austenitic stainless steel tubes prompted galvanic corrosion of the lead elements comprising the packing. Preventing such attack in a warm seawater cooled condenser was crucial to condensate quality. The fact that the tubes move with respect to the tubesheet greatly complicated the general plan to use an epoxy coating to isolate the tube/tubesheet joints from the cooling water. This paper describes the unique solution that was used to correct the packing deterioration problem. An epoxy tubesheet overlay was applied in a manner that accommodated tube translation. This was achieved by replacing the packing with high density polyethylene (HDPE) plastic ferrules molded with integral crevical knurls which formed a seal with the tube ODs. A single new fiber packing ring behind the plastic ferrule proved critical to the success of this concept. 5 refs., 6 figs.