The present invention relates to a polymerization process for producing olefin polymers in a loop reactor comprising two or more settling legs, comprising the steps of: —introducing into the loop reactor one or more olefin reactants, polymerization catalysts and diluents, and while circulating said reactants, catalysts and diluents; —polymerizing said one or more olefin reactants to produce a polymer slurry comprising essentially liquid diluent and solid olefin polymer particles; said process further comprising one or more cycles of: (a) allowing said polymer slurry to settle into said setting legs, and (b) sequentially discharging said settled polymer slurry from said two or more settling legs out of the reactor, whereby the aggregate time of discharge of all the legs is more than 50%, preferentially more than 80% and most preferably more than 95% of the time interval between two triggerings of the same settling leg.