A settling leg for a polymerisation reactor connected to the lower part of a loop reactor 1. A conduit 2 is welded to the loop reactor and leads to upper block valve 3 and lower block valve 4. Downstream of the lower block valve 4 is a further conduit 5 which leads to a lower region 6 and to a product take off (PTO) valve 7. Conduit 5 has a significantly greater cross-sectional area than conduit 2. In use, the block valves 3 and 4 are always open to allow slurry from the reactor loop to enter the settling leg. The PTO valve 7 is regularly opened to allow the settled polyethylene 'fluff' to be rapidly expelled along conduit 8. The greater area of conduit 5 significantly increases the settling rate and polymer concentration of the polyethylene 'fluff'.