Pipelines transporting different grades of crude oil or products usually operate with fixed setpoints for pressure limit switches and relief valves. These setpoints are calculated for a worst case condition as maximum flow rate combined with a sequence of batches of high viscosity ratio, etc. Under standard operating conditions, this worst case condition never occurs, so the setpoints restrict operating flexibility. With a transient simulation model it is possible to calculate these setpoints for actual hydraulic conditions on-line. Special attention has been paid to fail-safe operation of this on-line model and setpoint calculation. Our approach avoids all the problems linked to software in fail-safe applications and may be used for other applications of on-line simulation too. This concept has been successfully applied to a pipeline system in Austria, the AWP-Pipeline. With the new technology, substantial savings in energy costs (1–2 pump stations out of 11) as well as increased maximum throughput are possible now.

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