Methods of setting and retrieving a flow modifier in a pipe

摘要

A method of setting a flow modifying device (3) in a pipe (1) involves pushing the device (3) using a flexible pig (4) into engagement with a stop device (5) set into the pipe (1). Once the device (3) has contacted the stop device (5) fluid pressure in the pipe (1) forces the flexible pig (4) through the device. The device (3) can also be retrieved by removing the stop device (5), inserting a second pig (34, fig 2b) and allowing the pig to drive the device (3) along the pipe (1, fig 2d). The stop device (5) can be of two types. The first type (fig 3) requires that fluid flow in the pipe (1) is stopped for installation, whilst the second type (fig 4) can be installed whilst fluid is still flowing.