Head cut is made at the front end of interface at the first gravity change.
Midpoint is made at the middle of the interface.
Tail cut is made at the last gravity change before pure products.
Heart cut. A narrow-range cut, usually taken near the middle portion of the stock being distilled or
treated. A delivery of pure product is taken from the middle of a batch at some intermediate point of the
pipeline. A portion of pure product is taken from the line before and after the interface at intermediate
terminals.
Disposition of Interfacial Mixture. The disposition of interfaces is determined by product use limits.
Off-specification products whose qualities fall within established use limits may be used for their intended
purposes. The extent to which a product can be safely thrown off specification determines how much
adjacent product can be blended with it.
There are three alternatives for disposing of interfaces. These alternatives depend on the type of batch
change. They are as follows:
All of the mixture is cut in one or the other of the adjacent products. This protects critical products and
creates usable interfaces. The dispatcher should determine percentages if each product in the interface
is to be cut into the adjacent products.
The mixture is divided between the two adjacent products, usually at the mid gravity point. This provides
minimum contamination for both products if blending tolerances are considered. Dispatching personnel
should determine percentages of each product in the interface to be cut into the adjacent products.
The whole interface is taken off the line into a slop tank and is later blended with incoming product. This
mixture becomes a new product with its own identity. Dispatching personnel should determine the
percentages of product in the slop tanks that are to be used in blending.
8-5
QM 5096
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