Importance of Safety Critical Devices and Emergency Shutdown Systems in a Process Plant

Engineered Safety Systems are always a critical part of any hazardous process plant and should always be kept align with the design intent to avoid a catastrophic failure of the plant that can cause multi fatalities and lost time injuries. The maintainability of the safety systems especially emergency shutdown systems is always given a high priority for Safe operation and controlled shut down of the process plants.

Fatimafert Limited is an Ammonia-Urea Complex situated in Lahore, Pakistan. Ammonia and Urea plant is a high pressure and high temperature technology that deals with highly flammable and toxic chemicals at its manufacturing facility. The plant is considered High hazardous process and requires special focus on the maintenance and reliability of the equipments and devices to maintain safe operation of the plant and avoid loss of containment.

It is always a challenge to maintain and operate a highly hazardous plant of this vintage (1971). As part of Company’s roadmap for Process Safety Management implementation at the site, a comprehensive review of the existing procedures and practices was initiated with special focus on safety critical devices and equipments and their reliability.

This paper will cover the following major activities that were carried out to improve the inherent safety of the process plant:

• Preparation of a list of Safety Critical Equipments and Devices of all plants
• Development of a comprehensive Preventive Maintenance (PM) Plans of all Safety Critical equipments and devices
• Development of a regime for Functional testing of all available emergency shutdown securities and their logics for availability during extreme emergencies.
• Gap assessment of old vintage plant with latest plants for trip securities and emergency shutdown systems.
• A study for revamp of Emergency shutdown system of Ammonia plant to reduce reliance on human intervention for emergency handling.
• Development of detailed protocols for taking out of service these Safety critical devices with alternate control measures for safe plant operation.
• A comprehensive review of all the securities available in the design and their in-service status; taking them back in service through relevant HSE forums.

Implementation of these systems made the facility safer and reduced plant downtime by avoiding malfunctions / false trippings.