There will always be a bypass line in a process plant. However, are you having the correct bypass line set-up? A bypass line set-up is different if the line is used for steam or oil or slurry. If you are using the bypass for a steam line, you can have the bypass line at the bottom of the main line. You must also have a steam trap installed as well on that bypass line to ensure condensate water is released when necessary.
What if you have a slurry line? I was checking my email and found the
Cheresources newsletter that tells about this. The bypass lines should be placed above the control valve (as shown in the photo) so that the slurry cannot settle out and build up in the line during bypass. In addition to that, slurry lines should be sloped 1/2" for every 10 feet of horizontal pipe to avoid settling. Actually the steam line should have certain degree of slope to hinder water from settling and
further create water hammering which can destroy the pipeline.