Does anyone have any pics of bolt corrosion from two different types of metals being in contact with each other. I could also use a concise explanation on why using two different metals for bolts/hangers is incorrect. The area I'm climbing in has galvanized expansion bolts with stainless steel hangers and some plated hangers. I will post pics of anchors and bolts I feel need to be replaced.

I don't have permission from the locals on replacing the anchors/bolts and I figured this may be the safest way to approach the subject without hurting thier feelings.

Peace Eric

en.wikipedia.org/wiki/Galvanic_corrosion

The simple dirty answer is that different types of metal have a greater attraction for electrons than other types. As a result some metals steal electrons from other metals. The loss and gain of electrons results on the corrosion and loss of strength.

It's a little thing known as 'dissimilar metals'. Exact same reason iron and aluminum don't mix well.