This is very much confusing for me.
In P&ID it shows a gate valve and a check valve. the direction of flow is from check valve towards gate valve. line is to be routed for steam out. P&ID shows a process drain in between of these.
Is there any reason behind providing this drain? If yes plz somebody can explain?

In the same P&ID at another place again the same valves. but direction of flow is opposite. i.e. from gate valve to check valve. at this situatuin there is no drain valve in between of them but there is a drain after check valve. Does we require a drain valve between two valve here also?

Be sure that in both the cases the routing is such that you can not sandwich the valves. and service to flow is steam for steamout purpose

waitning for response

Thank You
Siddharth Jain