Labour shortages and higher demands on secondaryunits to meet tighter product specifications are changingthe cost and timing of US refinery turnarounds.US refiners are installing more hydrotreating and hydro-cracking units and running existing units harder to meetnew lower sulphur levels for diesel (AGM,23 October,p5).But catalysts in the units are now lia-ble to break down faster,and mainte-nance will have to be carried out morefrequently.Leading US refiner Valeroexpects to have to do turnarounds ondesulphurisation units every two years,in many cases.A crude or catalyticcracking unit can often run for four tofive years between full turnarounds.
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