Sabre Tubular Structures Provides Steel H-Frames to Repair Damaged Transmission Line

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Transmission & Distribution

Sabre Tubular Structures Provides Steel H Frames Essential in Repair of Damaged Transmission Line.

Residents in the Midwest are no strangers to harsh winter weather. But the major storm that struck southeast Iowa on February 24, 2007 and damaged a 20 mile stretch of 345 kV transmission line in Poweshiek County was more severe than even the hardiest Midwesterner expected. More than 269,000 utility customers lost power as a mix of freezing rain, high winds, sleet, and snow caused extensive damage to vital transmission and distribution infrastructure.

The damaged section of 345 kV line was part of a 36 mile north-south line extending from the Ottumwa Generating Station (OGS) to the Montezuma Substation and is considered the backbone of the area's transmission system. The two to three inches of radial ice that collected on the line exceeded the design capacity of the existing H-frames, causing the line to collapse and triggering a cascading failure that spanned 20 miles of the 36 mile line. In total, 81 structures were damaged.

TEAMWORK IN ACTION

To repair the damaged line and meet peak summer season demand, the customer required delivery of replacement structures as quickly as possible. To meet this aggressive timeframe, teamwork was essential. Fast response to inquiries and requests, quick turn around in drafting and design, competitive pricing, quality control, and sharing of internal scheduling were crucial elements in completing the project.

A-Frame Transmission Structures

Structures began shipping in April and completed shipping in June. The typical timeframe for design and fabrication of a job this complex would be close to 6 months with total completion timeframes as long as 30 months.

Laminated wood poles were considered for the reconstruction, but were ultimately eliminated due to cost and reliability considerations. Ultimately, steel was the product of choice and the new structures were designed to withstand future storms of this magnitude or larger.

To replace the damaged line, the job required 28 different designs and 3.2 million pounds of steel to complete.

CONCLUSION

Through the collaborative efforts of the owner, contractor, and suppliers, the redesign and rebuild of the transmission line was completed in less than 5 months. The line was restored to service on July 22, 2007.

Sabre Tubular Structures, the steel pole division of Sabre Industries, Inc.,
designs and manufactures tubular steel poles used in power
transmission & distribution applications, substation applications, and sports and high mast lighting.

Sabre Tubular Structures • 8653 E. Highway 67 • Alvarado, TX 76009
Toll Free: 866-254-3707 • Fax: 817-852-1703 • Email: utilitysales@sabre-sts.com

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