Ronstan RF2429 Series Padeyes — Care & Maintenance

Background

• RF2429-xx padeyes are investment cast from high-strength grade 15-5PH stainless steel.
• In Ronstan's salt-spray testing, prolonged exposure showed only occasional discolouration near the countersunk fasteners. Padeyes that corroded in the field were traced to cleaning products.

Unsuitable Cleaning Products

• Many boat cleaners and gel-coat stain removers contain hydrochloric acid (HCl); their MSDS lists them as potentially corrosive to metals.
• At full strength they typically contain 10-20% HCl and are diluted 1:10 for use, giving 1-2%. That has little or no effect on grade 316 stainless but attacks 17-4PH and 15-5PH.
• At that concentration the corrosion rate on 17-4PH and 15-5PH is seven times that of grade 316, and it doubles for every 10°C rise in temperature – faster in tropical climates.
• In Ronstan's test, a small amount of a diluted off-the-shelf gel-coat restorer brushed onto a padeye was enough to show obvious corrosion.

Products containing hydrochloric acid must NOT come into contact with 17-4PH or 15-5PH stainless steel products.

Care and Maintenance

• To restore the finish after exposure to aggressive cleaners, Ronstan recommended Polinox US Rust and Stain Remover: brush it on the affected padeyes and leave it no more than 30 minutes (longer blackens the stainless surface), then rinse off and wipe down.
• Further protection: apply a protective barrier film such as Interflon Film WB. Cleaning followed by a protective film performed very well in Ronstan's further salt-spray tests.
• Polinox US has since been discontinued by its maker; the replacements are POLINOX Protect Cleaner (repair and refurbishing of corroded surfaces) and POLINOX B Protect (TC) (immersion bath to improve corrosion resistance). Ronstan had not yet tested these when the note was issued.

Recommendation

• Always wash any cleaning solution away thoroughly with fresh water after use, making sure none pools or accumulates around stainless steel deck fittings.