Originally Posted by merziac

Get it all cleaned out and see how bad it is, if its all the way through then it may be time for a creative cutout, rust convertor, paint/seal, frame saver throughout and the sealed BB.

Originally Posted by daka

I own an un-galvanized boat trailer that is used in salt water so I am no stranger to rust. I don't think yours looks too serious. Rust has a much greater volume than the iron that created it so when you get that scale removed I think you will find you haven't lost that much of your bottom bracket after all. Even if it has perforated, remember that many high-end bike builders deliberately cut out material from that area so I wouldn't conclude that the BB is structurally compromised. Spraying some kind of anti-corrosion stuff (Frame Saver, Boeshield, etc.) inside the frame is probably a good idea. Sometimes the interior of old frames were treated with linseed oil when first built but that has probably long since dried up by now.