Emergency Outage and Restart
Day & Zimmermann (D&Z) led the restart efforts at a customer's plant following an emergency plant shut-down that occurred when a water hammer event caused damage to the cold reheat line. The line dropped eight feet resulting in significant damage to the plant. D&Z was awarded the full scope of the repair and remediation of the cold reheat line and sub systems. Once stabilized, the customer managed the engineering scope of the project with outside vender support including stress analysis. D&Z performed the following scope of work.
- Repaired structural damage including beams, grating, hand rails, stairways, and elevator support steel.
- Replacing 20 cold reheat piping spring cans, hanger rods, and friction clamps, along with damaged structural support steel.
- Replaced 100 feet of the vertical riser and the two 90° elbows on either end of the 36-inch cold reheat piping.
- Replaced portions of six electrical cable trays.
- Installed approximately 11 miles of cable.
- Replaced secondary piping that included extraction steam piping, soot blower piping, coal silo CO2 piping and several reheat drain systems.
- Replaced all associated insulation along with additional insulation that was removed for NDE inspections to verify that the remaining piping systems were of sound quality for continued operation.
- Welded eight 36” x .872” CRH piping joints, two 14” x .375” extraction steam, and a cold reheat drain valve.
- Coordinated the post weld heat treatment of all the 36” x .872” cold reheat piping welds that were installed by D&Z. 100% weld approval though x – ray testing. Work required maintaining proper rigging support to eliminate any chance of elongation or deformation to the affected piping.
Accomplishments and Innovations
D&Z mobilized immediately, and on-site staff reached 214 craft workers; 180 were new hires. Work was completed on schedule in four weeks. A total of 40,000 hours were worked with zero OSHA or DART incidents.