how to protect SG Iron.

[freewilly]

Hi Guys/Galls

I have a issue with protecting SG iron parts that are mated with steel (s275)parts, the two parts are then infused together with in a GRP part (this is the product interface). We can't hold the surface flatness required for the product so we are looking at machining the area (1800mm diameter about 200mm wide) then protecting it. Any ideas that will with stand a c5 (marine) enviroment, tempuratures down to -20c, and will give a 25 year protection and won't weaken the bond between the parts and the epoxy. The interface that produce is assembled to is protected by Hot thermal Zn spay, which is what we have been using on the Sg iron parts up until now (the steel parts are new to the equation). Did I remember to say that the products are 35m and 40m and will most lickly be getting bigger.

 

[kenvlach]

Why not use the same hot Zn spray on all metal surfaces (the machined SG iron surface, the rest of the SG iron and the steel) before epoxy coating?

 

[freewilly]

The part is manufactured in two moulds, the flatness problem comes about when we join the two half together. We can still Zn spray the part after join-up / machining, but it would mean a dedicated area and we all ready are having problems with space. moving such large objects around has its own problems, so I was hoping to find a method that could be applied during the finish phase and with-in the existing work space. Is there such a mirical solution.