Yokogawa Meets Tight 20 Day Shutdown Schedule for Replacing Legacy DCS with Integrated Solution at Mathura Refinery in India

• The removal of the existing systems, including 180 cabinets and 28,300 terminations, modifications to accommodate the new CENTUM VP system, in-stallation of new marshalling and system cabinets (201 cabinets), termination of signals (approximately 30,000), powering, loop checking, loop commis-sioning and system commissioning needed to be completed within a refinery shutdown period of just 20 days.
• For 400 signals, loop checking extended beyond the field junction boxes as the corresponding trans-mitters were to be replaced by Yokogawa HART transmitters.
• The "as built" I/O database was not available due to modifications that had been carried out over the past 10-15 years.
• No loop/logic write-up was available for the existing system.
• The DHDS AspenTech APC and connectivity to the plant LAN through a Honeywell PHD process information management system needed to be restored on the new system.
• The, suppliers had to be very tightly monitored as they had just eight weeks to deliver 200 cabinets (Rittal), 8,000 safety barriers (P&F), and work-stations and servers (Dell).

With the aim of having minimal re-engineering of control loops and ensuring the commissioning of the units on the first attempt, Yokogawa and IOCL's engineers worked closely together to expedite the following tasks:

• A task force was formed to directly retrieve data from field devices and the existing systems.
• Based upon the physically verified termination schedule, a new I/O database was created and compared with the existing system's database. To ensure the complete correctness of the new database, which had been designed based on existing documents, internal loop checking was conducted on the existing DCS after the plant was shut down. Any necessary modifications were then made to ensure the 100% mapping of field data needed for a smooth start up of the plant. This remained the key for making the system ready exactly as built at site, enabling a smooth re-commissioning of the plant.
• The IOCL engineering team physically validated all engineering inputs, which also served to double check the engineering database.
• Based on photos of the existing graphics, new graphics were created. Each and every type of graphic modifier (color change/blinking ) in the existing DCS was checked and recorded and then configured in the Yokogawa DCS so as to retain operational integrity after the revamp.
• With IOCL's support, all 3^rd party interfaces were engineered, validated, and commissioned on site.
• Staging and FAT for all six units was done in parallel at Yokogawa India, in close cooperation with IOCL.
• IOCL assisted by making building modifications to accommodate the removal of old cabinets and the installation of new cabinets.
• Given the tight schedule for the on-site work, a detailed hourly work plan was prepared for the period commencing with the receipt of the systems at the site. Necessary items were stored based on the order in which they would be used during the refinery shutdown period and consequent evacu-ation of space to make room for replaced system at stores to field loop checking up to field instrument.
• Commissioning of the hydrogen unit and parallel commissioning of all remaining units along with communications between the units were priority items during the shutdown.

All installation work was completed, units were powered on, loops were checked, commissioning was completed, and stable operation was achieved in a span of just 19 days - one day ahead of schedule.

The following key parameters were provided by IOCL as benchmarks for this project and each was met by Yokogawa India:

• Provide a best-in-class DCS/SIS solution on a robust, fast DCS network
• Integrate the DCS/ESD system network
• Ensure a robust HMI to be used as a direct node on the DCS network
• Provide a redundant ProSafe-RS SIS architecture for both ESD, from I/O level to CPU
• Include sequence of events (SOE) functionality with 1 msec event resolution for trip analysis and troubleshooting in the SIS - implemented as a built-in feature of ProSafe-RS
• Ensure stable control functions  - implemented rigorously through offline checks during pre-commissioning
• Strictly adhere to supply and shutdown schedule