Anything under pressure has the potential to explode. As far as PVC is concerned, many factors would be involved in when it would decide to blow. How often you use your air system, what kind of temps your plumbing will experience, was it glued correctly, are there any nicks or defects in the pipe, age, pressures, chemicals degrading the pipe, vibration effects, etc. Don't know if anyone has done any experiments to see what explosion time frame might be.
As always, common sense should prevail.
