Z--Heat Straightening at Lock and Dam 5A

Lock and Dam 5A Miter Gate Repair by Heat Straightening Scope of Work 1. General. The contractor shall provide all plant, labor and material to repair bent webs and flanges of the vertical miter girder member through heat straightening. 2. Repair Areas. The downstream intermediate wall miter gate was damaged as the result of a tow boat impact several years ago. The miter girder (last girder towards the centerline of the lock chamber) was left with an approximate four inch permanent distortion toward the lock wall on the upstream side of the member. This distortion is limited to approximately the top 8 feet of the member directly under the top horizontal girder. This permanent deflection does not allow the miter contact blocks to meet as intended. The miter girder is a built up member made up of 3/8 inch thick web plate and L 6 x 4 x flange angles. These components are riveted together. See attached photographs and as-built drawings. They are comprised of 1930s vintage ASTM A 7 steel. Required yield strength was specified as 33,000 pounds per square inch. See attached as-built drawing and damage photos. 3. Required Relevant Experience. The Contractor shall have at least 10 years experience in conducting heat straightening repairs for damaged steel structures. During the preceding three year period, the Contractor shall have conducted an average of at least five heat straightening projects per year. The personnel conducting the heat straightening must have a minimum of 5 years experience on heat straightening projects. Experience documentation shall include: date of project, location, bridge owner, number and type of members straightened, and duration of the project. 4. Equipment. a. Heating shall be with an oxygen-fuel combination. The fuel provided will be acetylene. b. Heat application shall be by single or multiple orifice tips only. The size of the tips shall be proportional to the thickness of the heated material. As a guide, the tip sizes shown in the table below are recommended. No cutting torch heads are permitted. Steel Thickness (in) Orifice Type Size less than 1/4 Single 3 3/8 Single 4 1/2 Single 5 5/8 Single 7 3/4 Single 8 1 Single Rosebud 8 3 2 Single Rosebud 8 4 c. Jacks, come-alongs or other force application devices shall be gauged and calibrated so that the force exerted by the device may be controlled and measured. No external force shall be applied to the structure by the Contractor unless it is measured. 5. Damage Assessment. a. Suspected areas of cracking shall be called to the attention of the Government before any testing or work is performed. 6. Heat Application. a. The temperature of the steel during heat straightening shall not exceed 1100 degrees Fahrenheit. b. The Contractor shall use one or more of the following methods for routine, ongoing documented temperature verification during heat straightening: Temperature sensitive crayons, Pyrometer, or Infrared non-contact thermometer. c. Material should be heated in a single pass and allowed to cool to below 250 degrees Fahrenheit prior to re-heating. d. Vee heats shall be shifted over the yield zone on successive heating cycles. e. Simultaneous vee heats may be used provided that the clear spacing between vees is greater than the width of the plate element. f. Repair of previously heat straightened members in the same region of damage may be conducted once. Further repairs of previously heat straightened members will not be conducted unless approved by the Government. 7. Application of Jacking Forces. a. Jacks shall be placed so that forces are relieved as straightening occurs during cooling. 8. Field Supervision of Repair. a. Heating temperatures shall be routinely monitored to ensure compliance with specified limits. 9. Tolerances. a. The dimensions of heat straightened structural members shall conform to the tolerances specified in the following table except as noted in paragraph 8. b. Member Type Minimum Tolerance Beams, Truss members, or Columns Overall At Impact Point inch over 20 ft inch over 20 ft Local Web Deviations d/100 but not less than inch Local Flange Deviations b/100 but not less than inch d is the depth of the member, b is the width of the flange b. Relaxation of the tolerance limits will be at the discretion of the Government based on one or more of the following conditions: Type and location of damage in the member or degree of restoration required to restore structural integrity. 10. Lock and Dam 5A Location and Lockmaster. Mr. Mark Beseler, Lockmaster W679 State Highway 35 Fountain City, WI 54629-7214 +1 (555) 000-0000 11. Government Technical Point of Contact. Ms. Elizabeth (Beth) Killian, P.E. 180 5th Street East St. Paul, MN 55101 +1 (555) 000-0000 +1 (555) 000-0000 (cell) 12. Government Provided Equipment, Personnel, and Services. a. The Government shall provide an aerial lift sufficient to accommodate the contractor's crew and tools. The Government will provide the operator for the aerial lift. The aerial lift and operator shall be made available for up to three work days. Use of the aerial lift and operator is restricted to regular duty work hours during the work week. It may not be used on federal holidays or weekends. b. The Government shall provide a means to transport the contractor's materials between the parking lot and the lock chamber. c. The Government shall provide crane support to place the contractor's tools and equipment on the aerial lift in the lock chamber. Use of the crane and operator is restricted to regular duty work hours during the work week. It may not be used on federal holidays or weekends. d. The Government Technical Point of Contact shall be on site during the heat straightening operation to offer any technical assistance/ approvals necessary to complete the work. e. The Government shall provide sufficient oxygen and acetylene gas to complete the repairs described in this scope of work. f. The Government shall provide jacking brackets per the contractor's submitted sketch at the contractors specified locations. The jacking brackets requested by the contractor shall be limited to an eight inch by quote mark thick angle (L8 quote mark x6 quote mark x quote mark ) with gussets welded for support. The bracket may only remove 3 rivets at a time when attaching to the gate. The bracket may be repositioned as needed limiting the removal of rivets to 3 at a time. 13. Site Visit. The Government will provide a site visit during regular duty work hours during the work week. It may not be requested on a federal holiday or weekend. 14. Schedule. The Contractor shall complete all work to straighten the bent webs and flanges of the vertical miter girder member as shown in the attached photos no later than 1 March 2015. 15. Coordination. The Contractor shall coordinate with the Lockmaster and Government Technical Point of Contact a minimum of five (5) work days prior to the scheduled start date to ensure all necessary arrangements for access, operators and removal of rivets have been made. If the contractor will need special jacking brackets installed, due to the repair location, the contractor shall provide the Government Technical Point of Contact the required location, a sketch of the brace and the material thicknesses to jack against a minimum of seven (7) work days prior to the scheduled start date to ensure fabrication and installation prior to the contractors arrival. 16. Submittals. All submittals shall be sent to the Government Technical Point of Contact. Electronic submission of required documentation is acceptable. At least three business days shall be allowed for review unless noted otherwise. All submittals are for Government Approval. a. Relevant Experience. Description of previous relevant experience as noted above in paragraph 2. This submittal is required within five (5) calendar days of contract award. b. Equipment Description. Provide a description of tools, equipment, and personnel to be placed in the aerial lift, to include weight and area. The weights of all equipment over 100 pounds must be provided to ensure the Government provides an aerial lift capable of accommodating the contractor's personnel and equipment. This submittal is required within five (5) calendar days of contract award. c. Calibration. (i) Documentation showing electronic temperature measuring devices have been calibrated within the previous year shall be submitted within 7 calendar days of contract award. d. Schedule. A schedule showing starting date and estimated ending date shall be submitted within 7 calendar days of contract award. Attachments: Photographs 1, 2, 3, and 4 As-Built Drawings: M-L5A-21-1 27 Foot Miter Gate General Drawing M-L5A-21-4 Details of Girders