Glossary · System coordination, integration and orchestration
Shutdown sequence
Also known as: Shutdown procedure
German: Abfahrsequenz
In industrial automation, a shutdown sequence is the defined series of steps by which a machine, unit or plant is brought from operation into a stopped, safe and consistent state, for example emptying lines, stopping drives in order and depressurizing equipment.
- System integration
- Process industry
In one sentence
A shutdown sequence brings a machine, unit or plant step by step from operation into a stopped, safe and consistent state.
Example
The shutdown sequence of a reactor unit stops the feed, finishes the reaction, cools the vessel, transfers the product and only then switches off agitation and heating.
How it applies
- Engineering: Design normal shutdown sequences so they leave the plant in a state from which a clean restart is possible. In the process industry, order matters: stopping upstream first avoids trapped material and pressure build-up.
- Commissioning: Test shutdown from every operating state, including partial operation and degraded modes.
- Operation: Automated shutdown sequences reduce operator error; the HMI should show progress and wait points.
- Documentation: Describe normal shutdown, shutdown for maintenance and shutdown after faults in the operating instructions, including checks at the end, such as confirming depressurization before opening equipment.
Shutdown sequence vs. emergency stop
A shutdown sequence is an orderly, planned stop for operational reasons. An Emergency stop is a safety function initiated by a person to avert an imminent hazard, with a defined stop category. Emergency shutdown systems in the process industry are safety instrumented functions designed to IEC 61511 and are also distinct from a normal shutdown sequence.