When utility systems are temporarily connected with a flexible hose to a process, hazardous substances can flow back into the utility system.
- During inerting, cleaning and unplugging operational equipment using utilities.
- When taking a sample a utility is needed to purge a system.
Challenges in the Field
- Lack of knowledge.
- Easy availability of utility stations & hoses.
- Hazard studies did not identify the hazard.
Options to Get it Right
- Awareness of the hazard that utilities can be contaminated with process gasses or liquids.
- Understand the pressures in the systems and how they can deviate during operation.
- Define suitable safeguards against backflow, at least one non-return valve must be present.
- Remove the utility hoses from the process directly when the task is completed.
- Ensure that the hoses applied have the same pressure rating and chemical compatibility as the process when used in normal operation.
- Evaluate backflow during MoC and HAZOP studies when fixed connections exist between utilities and process units.
This page only summarises the guidance – refer to the EPSC website for further information.
For more information on our Process Safety Fundamentals (or other) playing cards please contact us.