Understanding the Operation Dependency Chain and Error Handling

A dependency establishes a relationship between two or more operations. For example, if operation A is performed before operation B, then operation B depends on operation A. In the blend process, dependencies are also established through the vessels that are used in the operations. When you insert new operations or revise existing operations, the system has to recalculate the dependency chain.

Dependency chains cross with multivessel operations.

Operations that are performed on the same vessel share an implicit dependency. If two operations share the same vessel, the After lot of the first operation becomes the Before lot of the second operation.

You can instruct the sequence of operations, establish a link between unrelated operations, or establish a link between operations before common vessels are known. You can also insert operations into a dependency chain or remove them from it and recalculate the dependent operations. The system can report results in any sequence of the dependency chain.

Operations are linked in a dependency chain by common vessels. The order or sequence of operations in the chain is determined by the Actual Start Date.

If you create and schedule a new operation in the middle of a sequence of operations, the list of dependencies changes. The system automatically recalculates the new/revised operation and all downstream operations in the dependency chain. During this time all operations and vessels in the chain are reserved to prevent data integrity issues.

You can also reschedule operations by selecting the Re-Schedule Operations option on the Operations Header form and moving the date of the operation forward. The system moves the instructed start dates of subsequent operations accordingly.