A vessel header comprising a plurality of lateral flow tubes arranged in a parallel configuration and entering the vessel header through alternating header penetrations with a single header penetration per lateral flow tube. A method of increasing the throughput of a polymerization reaction comprising conducting the polymerization reaction in a reaction vessel comprising a plurality of lateral flow tubes arranged in a parallel configuration and entering the vessel header through alternating header penetrations with a single header penetration per lateral flow tube wherein the polymerization reaction displays an increase in throughput of 10% and a decrease in volatiles of from 5% to 10% when compared to a polymerization reaction carried out in a reaction vessel lacking a plurality of lateral flow tubes arranged in a parallel configuration and entering the vessel header through alternating header penetrations with a single header penetration per lateral flow tube.