The flow straightening vanes are used to reduce the flow turbulence made up by sudden way deviation as elbow, branch or valves, because their use often allow sufficient reduction of stream meter tube length, so that may be instalied flow meter instruments.
Two type of flow straightening vanes:
1) The Tubular type generally used for liquids and vapours
2) The Fin type generally used for gas applications
They may constructed for direct mounting in pipe line with locking device or with ring for mounting between RF flange.
This second type should be preferred because is the most widely used and it can be easily removed for inspection or pipeline cleaning