Temporary/Permanent Strainer

I doubt that any mandatory codes apply to this, though they might.

If a piping system could have initial debris in it, but no further source of contamination, temporary strainers/filters/"socks" can be used, and then be removed. This would apply to closed systems such as refrigeration piping.

If continuing contamination can be introduced, such as in open systems, permanent strainers/filters are desirable.

If downtime is undesirable, use duplex strainers/filters.

I agree; we are basically saying the same thing in different words.

Sorry, by my mistake below comment couldn't be seen, so i repost,it sorry once again

Hai Dear ,

What I understand and how I have used this terminology in my past projects.

Term "temporary strainer" in project is used as explained below.

Flushing of new system: when you build new piping, lot of debris (welding spatter, melts, soil etc) get accumulated. To prepare system for operational worthy, you need to put temporary strainer to block this debris to prevent debris to pass through the vital equipments. Usually a mesh is fixed in between the flanges like gasket. After passing flushing media for quite some time as specified by consultant or experts, open this area, remove this screen and clean this area. You will find lot of debris stuck in this portion.

Permanent strainer:

Permanent strainer is an integral part of a particular system by virtue of its design or system requirement. By word permanent strainer doesn't mean, you can not remove or repair it. By adding by pass across the permanent strainer you can remove or repair even when system is online.

I agree with some of the other comments in that a temporary strainer would be for system flushing prior to start up and then would be removed. You have provided little detail on the application. If the system needs a strainer or filter for the application you can have a by-pass as was already suggested but you can also have a duplex filter/strainer in-line. It amouts to having two strainers in parrallel with isolation valves so only one is functional at a time so that the system is always protected even if you are changing or cleaning an element. This would be used on applications that do not have regular maintenance shutdowns and are critical to have filtration maintained. The cost is of course appreciably higher as you have double the filtration installed and valving and space it requres.