Rusting stainless

Whink

Think Whink - Rust Stain Remover -- will do the job.
Rust Stain Remover | Rust Stain | Whink Products Company - America's #1 Specialty Cleaner Company, Eldora, IA

WARNING: Contains Hydrofluoric acid Hydrogen Fluoride (1.50 – 3.5%), and some Denatonium Benzoate (0.01 – 0.10%), SO?

http://www.wardrobesupplies.com/asse...pdf?1323898750

"Very toxic by inhalation, in contact with skin and if swallowed. Causes severe burns. Inhalation of vapors in high concentration may cause shortness of breath (lung edema). Ingestion causes burns of the upper digestive and respiratory tracts. Will penetrate skin and attack underlying tissues and bone."

Wear gloves and a good mask, eh?
Cheers!
-Eric

I need to ensure I'm on the same page. Your dink has a roll bar? Made of ? Stainless?
,rc

If the rollbar is stainless and was welded, it will always have re-occuring rust stains because of the welding. When Stainless steel is welded, the electricity odizes the metal throughout and it keeps coming up eventually.

Try polishing it with Collinite metal wax, keep the surface wet with the metal wax as you're polishing.....wipe off before it dries. After you do that, and the surface is clean and shiny, then apply Collinite insulator wax and allow to completely dry and then wipe off......

Try using this before you seal it. Spotless Stainless Removes Rust, Protects Stainless Steel

Stainless steel needs to have a proper acid passivation treatment applied after welding to prevent rusting at and near the welds.

And I find you get a lot long protection using a polymer sealant like Zaino, Rejex, etc. than you get with a true wax.

Stainless steel parts will rust after being welded if the weldor didn't know what he was doing and go the part too hot. If the metal gets too hot the chromium in the SS burn off. Chromium is the alloy in stainless which make it rust resistant.

After re-reading the original post a few times, 1) it is a stainless pipe of some kind, 2) it started after a stay in a yard where "we got some grindings off an other metal ship".
It is going to take some heavy rubbing to get the iron pits off/out the stainless surface. You may even start with 1000 grit and wet sand, move up to a compound, them finally a polish and wax.
Think of it as micro iron acne on your stainless. You may even feel it by your finger nail but can't see it (except for the rust stains that come back). These micro bumps cut thru the applied wax and will always be exposed to the air. They have to be flat and clean.