Maxi-Bolt Application - Steam Generator Retrofit

Drillco Maxi-Bolts have been used in steam generator replacements at the following plants.

  • Indian Point 2 - Consolidated Edison
  • Arkansas nuclear One - Entergy
  • South Texas Project - Houston Lighting & Power
  • Joseph M. Farley - Southern Company
  • McGuire - Duke Power
  • Byron - Commonwealth Edison
  • Braidwood - Commonwealth Edison
  • Shearon Harris - Carolina Power & Light
  • Ginna - Rochester Gas & Electric
  • Sequoyah - Tennessee Valley Authority
  • Problem: New platforms adjacent to the new steam generators at Consolidated Edison's Indian Point 2 Nuclear Power Plant were needed.

    Solution: The rebar congestion in the concrete adjacent to the generators made Maxi-Bolts the easy choice for this application because it would greatly reduce the number of anchors required. Instead of 8, and even 16 bolt baseplates they were able to reduce it down to 2, and 4 bolt baseplates. Drillco support, from engineering to manufacturing was available 24 hours a day from the early design phase through installation. This support is crucial for a job like this on critical path.


    Problem: A crane to lift the steam generator needs to be fastened to existing concrete. The loads being transferred are enormous.

    Solution: The 1-1/4" Maxi-Bolt has an allowable load of over 50,000 Lbs./bolt. If you are doing a factored design, you can increase the allowable to over 85,000 Lbs./bolt. Using the factored design approach, and a 4 bolt pattern you can get an allowable load of 340,000 Lbs./plate. The bearing type ductile design similar to a cast-in-place anchor, and the high allowable load gives the engineer confidence that he will be able to safely pick the generator.


    Problem: Lift points around the cavity are required to lift the generator.

    Solution: Flush mounted Maxi-Bolts have a threaded insert that allows an eye-hook to be turned down into. You can run a cable through the eye hook down to the generator. These flush mounted Maxi-Bolts have the same high capacity that stud mounted Maxi-Bolts have, and after use a cap can be screwed into the flush mount to protect the threads until it is needed again.

    Problem: Material Handling devices (conveyors) need to be anchored down, and they are subject to vibration and heavy loads.

    Solution: The Maxi-Bolt was designed for vibration. The bearing type design does not allow the Maxi-Bolt to slip out of the hole, even when loaded with heavy loads over several thousand cycles. The ductile characteristic would produce yielding of the steel as the load approached its minimum ultimate strength. With Maxi-Bolts, the engineer had confidence that he would be able to safely move the steam generator worth millions of dollars.

    Problem: Many generators are set up differently. The piping sometimes changes from one generator to another, and sometimes it can be large bore piping with heavy loads.

    Solution: Maxi-Bolts are known for their high capacities which can be used for large bore piping, but Maxi-Bolts can also be used in the ceiling for sustained tension supports like piping. Since the Maxi-Bolts retain a large percentage of their preload, retensioning of the Maxi-Bolts is not required. You can rely on shear friction to keep your piping right where you want it. Conventional anchors that do not retain preload need to be checked occasionally, and may slip out during the retensioning process.

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