Can I can string beans in my pressure cooker?

Please don't try to can in a pressure cooker. If you have a pressure canner, then you're good to go, but pressure canners and pressure cookers are two different breeds of the same animal. A pressure cooker (aside from being an unsafe method) would also require you to add additional processing time, so you're also running the risk of overcooking your string beans.

Here's a link with more explanation from the National Center for Home Food Preservation. http://nchfp.uga.edu/publications/nchfp/factsheets/pressurecookers.html