Why would you use 316 stainless steel?

316 stainless steel is a higher grade stainless. It is suitable for external corrosive environments such as near the ocean or around swimming pools. 

The higher the grade of stainless steel the better it can withstand better in corrosive elements. 

It will also require less maintenance than if it were of a lower grade of stainless steel. 

It is generally reccomended to be used in external applications.