BRADDOCK DAM MAINTENANCE BULKHEAD INSTALLATION PROCEDURE.pdf

Braddock and Charleroi L/D's, Painting Tainter Gates

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3.10 BRADDOCK DAM MAINTENANCE BULKHEAD INSTALLATION PROCEDURE

General. Four maintenance bulkhead units are provided for bulkheading the upstream tainter gate openings in the dam. Four bulkhead units are required downstream to bulkhead the non-overflow tainter gates and two bulkhead units are required to bulkhead the water quality tainter gate.

Bulkhead Units. Bulkheads are Pratt type steel structures, each with eight panels and triangular end panels. The bulkhead units (Reference Drawing 037-LBR-58/1) are six feet high and are 112'-11" center to center of bearings. Each bulkhead unit weighs approximately 82,000 pounds each. The bulkhead units are fabricated principally of high strength low allow structural steel. A bulkhead unit consists of two horizontal trusses with lateral and longitudinal cross bracing, with vertical channels and angles between the chords of the trusses, with watertight skin plating on the downstream side, with end bearing and side seal plates, and with J-rubber bottom seals. The units are of welded construction. Each bulkhead unit is provided with four permanent bars for connection of latching hooks on pickup frame for lowering each bulkhead unit individually into place in the recesses provided for it in the dam piers. The upstream bulkhead units and pickup frame are normally stored on pedestals behind the Upper Guide Wall, but will be relocated to blocking at the Upper Guide Wall by others to facilitate as shorter radius lift and pickup by the Contractor. The bulkheads must be picked from the Guide Wall with a floating crane, transported and placed in the appropriate gate opening in the dam. Movement from gate opening to gate opening must also be performed using a floating crane.

Pickup Frame. The pickup frame (Reference Drawings 037-LBR-58/8, 58/9, and 58/19) consists of two interconnected vertical trusses fabricated of steel pipes and structural steel spanning the gate bay with pickup points spaced 67'-9" apart. The approximate weight of the pickup frame is 25,000 pounds.The pickup frame is provided with a latching mechanism consisting of pawl, ratchet, spring assembly, connecting rods and 4 hooks for latching and releasing the bulkhead units. Latching mechanism operating procedure shall be as follows:

(1) Placing Bulkhead Units. The lever at the end of the pickup frame shall be set so that the pawl is in position to engage the ratchet teeth on top of the hook. On lowering the bulkhead to its damming position, the pickup beam shall be further lowered to rest on the bulkhead. As the pickup beam is lowered, the hooks will ride down and out of the lifting bars until the hooks are clear of the bars. The pawl and ratchet will hold the hooks in this position so pickup beam will disengage and can be lifted clear of the bulkhead units.

(2) Picking Up Bulkhead Units. The lever shall be set so that the pawl is held clear of ratchet on the hook. The lifting frame shall be lowered onto the bulkhead unit. The final positioning for hooking shall be accomplished by positioning devices on the pickup frame and bulkhead unit.

When the hooks contact the pickup bars they will be deflected against a spring until the pickup frame is lowered sufficiently for the points of the hooks to pass the pickup bars at which time they will be forced into hooking position by spring pressure.

Braddock and Charleroi L/D's, Painting Tainter Gates

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(3) All operations for placing bulkhead units or picking up bulkhead units and for engaging or releasing pick up bars should be confirmed by diver's inspection before and after each bulkhead operation.

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