The tube ends and the flange face are where the cladding often stops short, leaving a thin ring of exposed 316. That ring is a crevice and a corrosion point. The film must wrap over the end and onto the flange face.
The glass-fiber composite is applied with overlap at the ends. The pre-treated film is dense. Material-selection service specifies the end overlap on the drawing. At each outage, the tube end is inspected for lift.
Procurement buys the cladded heater with end overlap. The smooth surface prevents the crevice. The result is a tube with no exposed ring.
Plants that had end-corrosion found the cladding stopped short. The extended wrap fixed it. The result is a 316 heater whose ends are fully protected, because the film wraps over the tube end and onto the flange face.
The tube ends are where claddings often stop just short, leaving a thin exposed ring of 316 at the flange. That ring is a crevice and a corrosion point, and it is exactly where the operator would see a slow weep. The film must wrap over the tube end and onto the flange face, with deliberate overlap rather than a cut-off edge. The glass-fiber composite is applied with the end overlap built into the process, and the pre-treated film is dense. Material-selection service specifies the end overlap on the drawing, because a straight cut-off edge is a hidden failure. At each outage, the tube end is the first place inspected, because edge lift shows up there. Procurement buys the cladded heater with the end overlap as a standard feature. The smooth surface prevents the crevice, and the wrapped edge prevents the exposed ring. Plants that had end-corrosion traced it back to a cladding that stopped short, and the extended wrap fixed it. The result is a 316 heater whose ends are fully protected, because the film wraps over the tube end and onto the flange face instead of leaving a vulnerable ring of exposed metal.
At each outage, the tube end is the first place inspected, because edge lift shows there. Procurement buys the end overlap as a standard feature. The smooth surface prevents the crevice. Plants that had end-corrosion found the cladding stopped short. The result is a tube with no exposed ring, because the film wraps over the end and onto the flange face rather than cutting off clean.
The wrapped edge is smooth enough to seal with a filled-PTFE gasket. At each outage, the flange face is checked. The result is a joint that seals, because the film wraps over the end and the matched gasket seats on the smooth face.
Fabrication discipline is half the protection. Titanium heaters must be built on dedicated benches with non-ferrous tools, so no steel particle embeds. A filled-PTFE liner then covers the cleaned titanium and prevents both galling and iron-induced pitting. The glass-fiber filler is non-conductive, so no galvanic cell forms. After the liner is applied, an iron-test swab checks any exposed flange. The fabrication binder records the tools used. At each turnaround, the smooth liner is holiday-tested. The result is a heater free of hidden iron.
