Automating a SIS Upgrade Project

Wednesday, June 7, 2017 @ 03:06 PM gHale

By Gregory Hale
Chevron had a refinery sulfur recovery unit furnace SIS upgrade project and they knew the old way of doing things just would not cut it this time around.

They felt they needed to automate the process and be able to get it up and running much faster.

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That is where the Triconex Safety Validator (TSV) came into play as they knew the automated application logic testing system would save time, money and effort.

“We took company standards and we were able to create a ‘truth table’ that could take TSV scripts and created over 100,000 lines,” said Tim Cagle, control systems engineer at Schneider Electric during a session he and Ken Harris, SIS engineer at Chevron Refinery, gave entitled, “Automated application logic testing lessons learned and examples of how automated application logic testing can save time, money and effort” at the 2017 27th Annual Triconex User Group meeting in Lake Forest, CA. “We were able to create a function block library. That allowed us to use good documentation.”

Safety Validator software can perform logic testing at the press of a button. It can create tests in a structured environment; can execute tests; includes auto-run, single-step and select test cases; display automated test results; has an option for entering manual tests and showing pass/fail results, and can repeat and rerun tests. It can minimize the time, cost and effort of testing safety application logic, and increase test quality, while reducing human errors.

In the sulfur recovery unit case, “TSV ended up used for function block certification for 15 blocks and for integrated software FAT for the TriStation Emulator, Honeywell TDS and PanelView Alarm Panel and for SAT commissioning,” Harris said.

The results from the function block certification include:
• Standardized function block library developed and certified
• Over 100,000 lines of test scripting for the most complicated block
• Each function block was exhaustively automatically tested with test results documented
• The final effort provided the project team with a high level of confidence the function block library was of sound design before going into FAT

“For integrated software FAT, we had six complex furnaces where each furnace had an automatic purge/lighting sequence. Just getting the furnace lit manually is quite a process if you do it manually,” Harris said.

There were about 280 shutdowns tested and the scope included the Tristation Application (.PT2), the Honeywell TDC DCS Graphics and Alarms and the PanelView HMI.

Time Savings
Software FAT using TSV scripts saved about two weeks of testing time and provided consistent and reliable equipment resetting for Safety Instrumented Function (SIF), Harris said.

When it came time for SAT and commissioning, management was hoping for a shorter time frame.

A previous validation on a similar SRU unit took 9 (24 hour) days for 2 furnaces (manually forcing points for resetting furnace between SIF trip checks), Harris said. To avoid being “critical path” on the turnaround, the team ended up allotted 5 (24 hour) days to validate this six furnace system.

Time savings involved reducing the “dead time” spent on equipment restarts. To this end, the team used TSV to automate furnace reset versus doing it manually.

The end result showed by employing TSV, the team was able to reset each furnace in an average of 20 seconds; where it typically took 5 to 10 minutes manually.

“It was less cumbersome to do the restart; less time and there was better team engagement,” Harris said.

In addition, there was an 85 percent reduction in validation time as the team was able to validate all six furnaces in 4 days (8 shifts). On average, the validation hours required per furnace reduced from 108 to 16.

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