Safety roundtable opens Frame 6 Users’ 30th anniversary meeting

Frame6 LogoFrame 6B gas turbines are the heart and soul of many cogeneration systems serving process plants in the primary-energy and chemical industries. The O&M personnel responsible for these assets typically are challenged by demanding managements to ensure high availability and performance on depression-era budgets. Those who thrive in this anaerobic environment have a practical, solutions-driven mindset that makes doing more with less a way of life.

It is not news that many cogen facilities are not supported by a corporate engineering staff. Success often hinges on the talents of deck-plates personnel, many of whom consider the Frame 6 Users Group their “technical solutions lifeline.” The ability to share information in an open forum is the reason many owner/operators of 6B engines continue to attend meetings year after year—some since the group was founded 30 years ago.

The 2016 conference was conducted at the PGA National Resort in Palm Beach Gardens, Fla, June 13-16. No time for golf, however; all business. Speaking of business, Geoffrey Kret, Total Petrochemicals USA, an active participant and discussion leader since the organization’s first meeting, resigned from the steering committee prior to the conference because of new responsibilities at Total. Wickey Elmo of Goose Creek Systems, conference manager and steering committee member, retired immediately following the meeting.

In their opening remarks, co-chairs Jeff Gillis, ExxonMobil Chemical, and Sam Moots, Colorado Energy, reviewed the hotel’s emergency evacuation plan—a perfect segue to the opening roundtable discussion on safety. Gillis may be the ideal session leader on this topic given his global perspective. He has engineering management responsibilities at ExxonMobil for generating equipment worldwide, which requires learning how other countries and cultures assure worker safety and understanding their regulations. OSHA is not global, and America does not have all the answers.

The safety roundtable focused on fire protection/prevention. By show of hands, most attendees rely on CO2 systems for package fire protection. Here’s how these systems typically work: Initial release floods the compartment to quickly reduce the amount of oxygen. Injection of the inert gas then continues, to guard against re-ignition.

Point was made that it takes time to put out a fire and cool down the package to prevent re-ignition. Be sure there’s a sign like this on the door: “Do not open door when CO2 is being released.” Drive that point home in training, a user suggested to his colleagues. At the recent 7F Users Group conference it was mentioned that operators believed an insulation fire was out and opened the door only to have flames appear once again.

One attendee stressed the need for positive shutoff of the CO2 system when work is being done in the compartment. He mentioned a near miss as motivation for a piping modification at his plant. One way to prevent an accidental discharge, he said, is to install a gate valve in the CO2 line to the compartment and chain it shut as part of the lock-out/tag-out (LOTO) process.

Two more ideas:

      • Remove the heads of the CO2 cylinders and replace them when package work is completed.

      • Put a time delay on CO2 release—say 30 seconds—with lights and alarms. This should allow enough time to get out of the package before CO2 introduction.

Attendees were reminded to train operators to be sure doors are closed and gas-tight before a unit restart. However, testing of door seals may have a downside during a time-constrained outage. It takes about a day to run the test, a couple of days to fix leaks, and another day to re-test. That’s about four days if leaks are not found during the second test—which is not unusual.

Also important is to exercise package louvers regularly to verify they are in working order. Example: Weekly use a test blow of compressed air to see that louvers close properly.

Testing of the CO2 system should include all piping, another user said. He recalled an incident in which CO2 piping passing through the control cab (which didn’t have or need CO2 protection) leaked, forcing personnel to evacuate. CO2 bottles often are located indoors and can pose a danger if connections leak. An attendee said his plant uses a scale to determine if CO2 is leaking.

Another point made: Sometimes too much “safety” creates an unsafe condition and/or impedes reliable operation. For the plant, he said, concerns go beyond the gas turbine; for the OEM it doesn’t. Example: OEM might want to trip the gas turbine if a sensor says the door is open or if ground faults are identified in detector wiring. But the owner certainly doesn’t want to trip the refinery unless an unsafe condition can be confirmed.

Another concern brought to the floor: Possible conflict between European and US safety standards regarding the Frame 6B, which now is made in France. Be sure to do your homework.

Water mist technology was discussed as an alternative to CO2 because of its inherent personnel safety aspects. One participant said his company had installed a mist system on one unit to gain some experience before making a decision on whether to replace its CO2 systems on all units. Here are a couple of things to keep in mind if you think water mist might be a good fit for your plant:

      • The failure of a solenoid valve can compromise reliability.

      • Water pump should be powered by compressed air or nitrogen. Electric pumps are not recommended because electricity may not be available.

      • Icing is a possible problem at low ambient temperatures.

      • Demin water was recommended by a couple of users.

      • Water storage tank should be sized to allow misting for at least 30 minutes.

      • Annually, change water in the tank “to keep things from growing.” At the same time, check the entire system to be sure there are no leaks and the fog nozzles are performing as expected.

One attendee questioned the logic of spraying water at ambient temperature on a hot casing. He was told a fine mist would not be harmful, but streaming water and drips could be (see last bullet point above).

Suppression system reliability was the next discussion point. Interesting was that no one in the room had experienced a fire in the last five years, although several were impacted by suppression (CO2) dumps. Thus attendees couldn’t comment first-hand regarding the effectiveness of either system for extinguishing a fire.

Filter-house fires got a quick mention—including the fire caused by contact of a halogen lamp with dry filter media. This had been discussed at several conferences previously. The safety message regarding lighting was obvious: LED is the way to go. Another safety message regarding inlet houses: Provide egress on both sides of the house and at all levels to avoid being trapped in the event of a fire. Industry experience confirms that a filter house with dry media can be totally consumed within few minutes after a fire starts.

Discussion of safety during outages came at the end of the session. Most plant managers say they empower their personnel to stop a job when they believe they see a safety issue. That’s all well and good, an attendee said, but you generally don’t want the person stopping the job to suggest how to mitigate the issue observed.

Reason is that most observers are not sufficiently familiar with the situation/equipment to offer a successful on-the-spot solution. The user commenting said the changes proposed by the observer might be—often are—more unsafe than the original plan. Best plan of action: Stop the work and bring the job supervisor and other experts into a room to review the reason for calling a halt to the activity and to agree on a solution.

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