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Clearance processes are basically designed with two objectives/priorities in mind:
- Safe isolation of energy sources to protect employees.
- A process, for the operational group with overall jurisdiction, to manage scheduled and emergency work and outages with system conditions.
There can be many obstacles associated with clearing equipment. Transmission gas and electric clearances have clearance points stretched over miles of line, clearances which cross jurisdictional boundaries (both internal and external to the respective utility), clearances which take place between utilities and may have a common clearance point with a clearance tag attached for each utility, different criteria and locations for Reporting On and Off cleared equipment, remote Reporting On/Off, and so on. Within the bounds of this article, I will not attempt to list every potential scenario.
Step 1: Author and Approve the Clearance
Updated operational maps, single line diagrams, schematics, P&IDs, etc., are used to choose the points which adequately clear the affected equipment. The clearance is authored by a subject matter expert and approved by a supervisor and the operational group with the final OK authority. The points shall be verified with a walkdown and any needed revisions are then submitted for change on the clearance and associated drawings. Critical Safety checks are inherent in this first step to ensure the right equipment is properly cleared prior to beginning work.
At Bluegrass Generating Station, the operations group (Ops) is the Clearance Supervisor (CS). They clear the equipment and make it available. They are the first to Report On a clearance and the last to Report Off. It's a requirement -- we must ensure our operators, who are responsible for the safe and efficient operation of our 1,000 megawatts of generation, are in complete control of their equipment. The maintenance and/or construction folks who want to Report On and do the work will be classified as secondary clearance holders. The clearance supervisors manage the Master Clearance Board and all secondary clearance holders Report On and Report Off to the CS.
Step 2: Place Master Clearance Point (MCP) Man On Line (MOL) Tag
This point is on the centrally located Master Clearance Board. This is the location where all station employees can see the equipment that's cleared and ensure their Master Clearance Point tag is posted and that they're Reported On, prior to beginning work. While the MCP MOL is in place, the equipment is not to be operated.
Step 3: Clear Field Points
The breakers, valves, switches, etc., required to isolate and clear the energy sources from the affected equipment are placed in their cleared position and tagged with the appropriate MOL/Caution tags. As the equipment is being walked down/cleared, points are being checked as adequate and any required changes are verified, approved and included in the clearance package. This is another critical safety check to ensure the right equipment is properly cleared.
Step 4: Report On the Clearance
Any person requesting the clearance has walked down the clearance points as defined in the clearance package and is Reporting On the cleared equipment. This is another critical safety check. They have ensured the equipment is safely cleared and they are ready to perform the work required. As long as they're Reported On the clearance, the tags placed on the clearance points will protect them from all energy sources. When they're Reported On, the tags are not to be breached and shall remain in place until the person Reported On has Reported Off.
Step 5: Perform Work/Testing
Work proceeds to completion and the equipment may be tested. Of course, we won't energize/test equipment while others are also Reported On the clearance, so they'll have to Report Off while testing is performed. Some tags will probably need to be changed for testing, and the Clearance Process in place will define the specific sequence required to accommodate changing of tags for testing of cleared equipment. At the conclusion of the test, any others who may need to report back on to complete their work may do so, or the equipment can be placed back in service, as applicable.
Step 6: Report Off the Clearance
Work has been completed by those Reported On, the equipment has been tested functional and can be made available for service. We must Report Off, prior to removing tags. If tags can be removed while employees are still working on equipment, then Step 4, above no longer provides any protection.
Step 7: Remove Field Tags and Return Clearance Points to Normal Operating Positions
The breakers, switches, valves, etc., used to isolate/clear the equipment are returned to their normal operating positions. Clearance tags are removed as the points are returned to normal.
Step 8: Remove Master Clearance Point MOL and Report Equipment Ready for Service
The MCP MOL is removed and the clearance is closed out. The equipment is now considered available for service. The designated clearance tags and clearance package can be retained, as required.
This eight-step process will absolutely ensure employee safety while working on normally energized equipment at Bluegrass Generating Station.
The basic design of a clearance process should be a fundamental part of the safety culture at any utility. It is, however, only a tool. And as such, if only partially utilized, or misused, the margin of error can have deadly results. With any safety process at your facility, I urge you take the time to refresh yourself on the content and spirit of the process. Stay engaged and look for opportunities to recognize deficiencies. Understand the process and communication chain for revision, when you spot a potential issue. Be safe, watch out for the safety of your brothers and sisters on the job and take action against unsafe situations.
Never lay your armor down when it comes to safety.