For the record- I worked for about 4 years in a dairy where they welded stainless steel piping together on a regular basis and I can assure you there were no rough edges inside the pipe. This would still not permit to be used as a raceway per the NEC. I would not have a problem if it were parted of a listed assembly as reviewed by UL. My reason for posting is to tell you SS piping as used in a dairy is absolutely smooth both inside and out due to the special welding process and the need for sanitation and ease of cleaning.
