Is there a recommended sanitization/maintenance program for a distribution system for process air piping?

The use of properly rated terminal filters (with verified integrity/particulate removal efficiency) is sufficient to secure no risk of undue product contamination, along with suitable sanitary piping downstream of the filter. Most sanitization/maintenance programs would focus mainly on the terminal filter and piping downstream from the filter. Upstream, you would need to ensure that air has been properly dried and the piping is free from any leaks. This would need to be monitored as part of your maintenance program.