Various urea producers and engineering firms have developed ways of minimizing or avoiding the problems in urea manufacture. The usual practice in reviewing urea technology is to discuss each company process as unit. In the present discussion, however, each principal design or operating problem will be treated as a unit and the contribution of each company given; the main companies involved are Chemical Construction Corporation (Chemico; U. S.), CPI-Allied (Chemical Processes of Ohio, inc.-Allied Chemical Corporation; U. S.), Lonza AG (Switzerland), Mitsui Toatsu Chemicals, Inc. (Japan), Montecatini Edison SpA (Italy), Norsk Hydro-Elektrisk Kvaelstof A/S (Norway), SNAMProgetti SpA(Italy), Stamicarbon NV (The Netherlands), and D.M. Weatherly Company (U. S.).