3

BOARD OF INVESTIGATION NEW ORLEANS DISTRICT

OLD RIVER LOCK: FLAT BRAID WIRE ROPE FAILURE, 30 Jan 2007 1. GENERAL: a. Purpose: This board of investigation was convened on 21 March 2007 to gather and evaluate information to determine the cause of the property damage incident occurring at Old River Lock, New Orleans District (MVN), on 30 January 2007; to develop recommendations for the prevention of future occurrences of similar accidents; and to prepare a report of the investigation, findings, and recommendations. b. Authority: USACE Supplement 1 to AR 385-40. d. Accident Summary: On 30 January 2007, employees at Old River Lock, New Orleans District, conducted a maximum load test on the emergency bulkhead machinery. During the process, the flat braid wire rope failed which resulted in the dropping of eight bulkheads. In addition to the failed/broken wire rope, structural damage was caused to the eight bulkheads and superficial damage to the lock wall. 2. DESCRIPTION: a. Construction of the Old River Lock was completed, and the Lock became operational in 1963. As is common for U.S. Army Corps of Engineers Locks, steel bulkheads are used for emergency and/or maintenance situations. This lock has four slots (one upstream and one downstream of each miter gate). In the event of an accident, the slot on the Mississippi River side is used for emergency closure. Bulkheads for this slot are equipped with rollers to allow lowering all of the bulkheads at once under high velocity flows. To set the bulkheads, two separate processes and equipment are utilized. First, a crane (See Appendix A: Photo 1) is used to lift and set the bulkheads onto a lowering carriage (A.K.A. sinking block with rollers) (See Appendix B). The lowering carriages are set within recesses in the lock chamber walls. Second, a winch system is used to lower and raise the bulkheads to the bottom of the lock chamber. This system includes a flat braided wire rope (See Appendix C). It is a unique wire rope configuration made from fifteen 5/8-inch diameter wire ropes held together side by side with hand-stitched seizing wire. b. On 30 January 2007, a maximum load test was being conducted on the emergency bulkhead system before final acceptance of new Programmable Logic Controlled (PLC) motors. Seven bulkheads were successfully set and lowered. As bulkhead 8 was lowered, employees heard a binding/squealing/popping sound. The crane operator was directed to raise the bulkhead to the

4

level of the lock wall. As employees were observing and discussing potential causes of the sound, the wire rope on the north side of the lock failed suddenly (See Appendix A: Photos 2 and 3). 3. FINDINGS: a. Background Information: The wire rope was the original material installed in the early 1960’s. The cable was at least 45 years old, and there is no evidence that it was ever subjected to a maximum load test. The lock gatebay was dewatered in 1979, and 6 bulkheads were used; however, a maximum load test (12 bulkheads) was never attempted until January 2007. b. Physical Evidence: The failed portion of the wire rope was not available for the board’s inspection. Following the accident this portion of the wire rope was taken to Yarbrough Cable Service in Memphis, Tennessee, and tested for tensile strength. A test certificate dated 2 March 2007 certifies the sample provided failed under a load of 515, 900 pounds. After the testing the sample was left at the Yarbrough plant and disposal occurred. The remaining portion of the wire rope was onsite and available for inspection (See Appendix A: Photos 4 and 5). This portion of the wire rope was covered with a heavy grease coating making it difficult to inspect; however, small uncovered areas revealed external corrosion. The entire lowering carriage system had been sent for maintenance and was unavailable for the board’s inspection. In order to inspect a similar lowering carriage system, the board visited the Port Allen Lock (See Appendix A: Photo 7). c. Interviews: (1) On site interviews were conducted with the Old River Lock project employees, MVN shop employees, and project operations management. The Old River Lock employees witnessed the accident, and the MVN shop employees inspected the wire rope approximately 3 months prior to the accident. Interviews with the inspection team indicated corrosion was found in one area but it was superficial (could be removed with a wire brush). In addition, other MVN operation and engineering employees were consulted. (2) Mr. Dan Merrell of Yarbrough Cable Service and Don Pellow of Pellow Engineering Services were consulted via telephone following the site investigation. d. Chronological Events: (1) The Old River Lock opened for operation in 1963. There is no evidence of an emergency bulkhead load test. (2) In 1979 the river side gate bay was dewatered for maintenance reasons. Six bulkheads were needed for dewatering purposes. This is the only record of a load test of the system prior to the January 2007 accident. (3) In 2003 a solicitation was generated for new direct drive electric motors and PLCs for the lowering carriage system. This replaced the hydraulic drive system. This solicitation included new flat wire rope. This equipment was delivered in 2004. (4) Shortly after the above equipment was ordered, problems with the flat wire rope at Port Allen Lock were communicated to Old River Lock.

5

(5) Old River Lock project personnel decided to delay installation of the new wire rope until the wire rope problems at Port Allen Lock were resolved (See Appendix A: Photo 6). (6) In January 2005 Periodic Inspection Report No. 8 pointed out problems with the lowering carriage system. The report recommended replacement of the hydraulic motors with new inverter duty brake motors controlled by variable frequency drives and operated by PLCs. The report did not specifically address the flat wire rope but pointed out that the use of the crane and lowering carriage system would be problematic with little chance of success in an emergency situation. This assessment was based on the age of the system and lack of operation. (7) Since installation of the new wire rope was delayed, project personnel decided to inspect the old (in service) wire rope. MVN shop personnel were utilized for an October 2006 visual inspection and lubrication of the old wire rope. An email message dated 27 October 2006 stated the wire rope had been inspected and was in good condition except for broken binding wire in three different locations. (8) In January 2007 the new electric motors and PLCs were installed. (9) To test the new electric motors and PLCs a load test was planned for 30 January 2007. Even though the system was designed to carry 12 bulkheads, this test was intended to lift 10 bulkheads. Project personnel decided this would be adequate to test the system. (10) On 30 January 2007 the above test was conducted leading to the wire rope failure as described. e. Description of Hazards: A Critical Lift Plan was prepared for the load test and implemented in accordance with EM 385-1-1, section 16.C.18. The Critical Lift Plan recognized recent upgrades to the crane’s electrical system that resulted in new electronically-imposed limits to radius and capacity. With the electronic load limits the crane no longer had sufficient capacity to reach the bulkhead slots with the bulkhead and pickup beam. To provide personal safety the pickup beam was designed for automatic pick-up and release action, but it weighed 13,000 pounds. It was found that by using lighter manually-attached slings, the crane could reach the bulkhead slot with the 66,000 pound bulkhead with a small 2,000 pound safety margin. As a result, the pickup beam was removed from service. Now direct hook-up to each bulkhead is required. After the crane lifts the bulkheads into place, a worker is required to walk out onto the bulkhead and release the connections. During the January 2007 load test, the worker performing this activity was tied to a safety line and safety procedures were followed. The worker was not on the bulkhead at the time of failure. No overhead utility lines were observed by the board. f. Related Information: The hazards of lifting heavy bulkheads with old equipment have resulted in other bulkhead accidents. Port Allen Lock in Port Allen, Louisiana, has a bulkhead hoisting design very similar to Old River Lock. Port Allen Lock had two separate bulkhead accidents on 17 and 19 October 1990. Each accident has its own Board of Investigation Report. On 17 October 1990, a bulkhead was dropped onto Control House No. 1 because of a rigging failure while lifting with the crane using manual slings. On 19 October 1990, a bulkhead was dropped while suspended in the bulkhead slots by the pickup beam due to a bulkhead hoist brake failure and subsequently the pickup beam latch was jammed.

6

4. CONCLUSIONS: The board’s conclusions are based on wire rope industry consultation, research, interviews, photos provided, and inspection of the Port Allen Lock lowering carriage system. a. Primary Factors Contributing to the Accident: (1) Age of equipment. The wire rope was 45 years old. Even though there are no records of the original manufacturer and warranties, 45 years exceeds the general life expectancy of flat wire rope. This can vary depending on application and exposure. (2) Design of the emergency bulkhead system. The following statements were extracted from Design Memorandum No. 9A dated April 1959. (a) “The lifting sheave will have a diameter of 20 inches which is smaller than usually recommended for the 5/8 in. x 8 in. flat wire rope. However, since the bulkheads will be operated infrequently, the life of the rope is not a factor.” This board believes the design should have given more consideration to potential for corrosion and normal deterioration of wire rope. Also, the board believes the sheave diameter could have been a contributing factor in the accident. Consultation with Mr. Dan Merrell, VP of Yarbrough Cable Service, revealed the recommended sheave diameter is 30 inches. According to Mr. Merrell the wire rope strength would be reduced significantly by failure of the sheaves to operate properly or by permanent storage in one position causing a kink where the rope wraps 180 degrees around the carriage assembly top sheave (See Appendix B). Interviews with project personnel indicate the top two sheaves were operating properly, but revealed the rope failure could have occurred at or near the above-mentioned bend around the sheave. (b) “Because of the slow rate of lowering, it was not considered necessary to include any allowance for impact.” Also, review of the original design indicates there was no allowance for obstructions, binding, and inoperable sheaves. Our interviews indicate the bulkheads were loaded onto the lowering carriage very carefully with no impact loads. While there was no direct evidence of these factors contributing to the accident, consideration of these factors in the design would have resulted in a higher factor of safety. (c) Flat wire rope design. The email documenting the October 2006 inspection results revealed failure of the binding (seizing) wire in 3 locations. A load test of a similar system at Port Allen Lock resulted in multiple binding wire failures and ultimately damage to the wire rope. The binding wire does not add tension strength, but its failure allows the flat wire rope to open up and damage occurs when wrapping on itself. (d) In summary, the original design provided a factor of safety of 3.2 which falls short of today’s requirements. EM 1110-2-3200 dated 30 September 1998 requires a minimum factor of safety of 5 for dynamic loaded rope. Also, the flat wire rope is obsolete and no longer recommended by the above EM. (3) Failure to conduct the wire rope inspection with a qualified team. In October 2006 a team of MVN shop personnel was directed to perform a visual inspection of the wire rope. This team had no training for this purpose and was not qualified to conduct this type inspection.

7

(4) Miscommunication between Old River Lock and Port Allen Lock. Failure to install the new wire rope at Old River Lock was based on problems with the wire rope at Port Allen Lock. However, there was confusion and misunderstanding as to differences (if any) of the new product. Even though the two products are similar, it is the board’s opinion the new wire rope has improved binding (seizing) wire. This along with addition of a hoist drum spacer should reduce the problems incurred at Port Allen Lock. In hindsight the new wire rope should have been installed.

b. Indirect Factors: (1) No guidance regulating wire rope replacement. There was no guidance provided on the wire rope life expectancy and replacement cycle. (2) No maximum load test ever. There is no documentation that the system was load tested at its inception in 1963. All the equipment and material is original and is 45 years old. (3) Inadequate maintenance of the wire rope. The wire rope was lubricated with heavy grease. This is not approved by EPA and is not recommended by the wire rope industry. It has been determined that heavy grease tends to hold moisture in the wire rope rather than keep it out. Also, it catches dirt and debris that can damage the wire rope. Wire rope provided by Yarbrough Cable Services comes with a lubricant that has been approved by EPA. (4) Added bulkhead weight. The bulkheads were recently repaired and upgraded to comply with Hydraulic Steel Structure criteria. Interviews with project personnel revealed serious concerns about the added weight. In consultation with MVN engineering, this board determined these concerns were unfounded. The additional weight was less than a 1% increase and thus considered inconsequential. 5. RECOMMENDATIONS: a. OPERATING PROCEDURES. As an interim measure install the new wire rope previously purchased and onsite. Procure the services of a professional wire rope consultant and inspector. Two such companies are Pellow Engineering Services in Kansas City, Missouri, and Longview Inspection in Laport, Texas. Utilize this service to inspect the damaged wire rope at Port Allen Lock, provide advice on corrective measurements needed for both locks, and train project personnel in the proper use and maintenance of wire rope. Develop mandatory wire rope lifespan replacement criteria and a process for periodic testing until a new emergency bulkhead lowering system is added. b. NEW EQUIPMENT DESIGN. This system provides emergency closure through the main line Mississippi River Levee and its importance cannot be over emphasized. Flat braid wire rope is no longer standard industry practice for this use. EM-1110-2-3200 recommends against the use of flat wire rope. For a long-term solution this board recommends development of a team to design a new emergency bulkhead lowering system. Based on input from project personnel, there is a need for a system that can be tested on a frequent basis (yearly +/-) to assure employees are trained and prepared for emergencies. With this in mind, a new design concept will be needed. This design will need to comply with the latest regulations and accommodate frequent use. One

8

option would be to change the hoisting system to use large conventional (round) stainless steel wire ropes or a large roller chain. Other options should be explored as well. 6. ANCILLARY CONCERNS: a. Port Allen Lock. The board’s findings and recommendations are directly applicable to Port Allen Lock. b. Old River Lock crane limitations. The existing portal crane's builder (Colby Manufacturing) no longer exists. This crane was recently rehabilitated and had electronic load limiters installed. Based on interviews with project personnel, it appears the rehabilitation cost approached the cost of a replacement crane (Manitowoc 2250 or similar). A replacement crane would have provided increased capacity to lift bulkheads with the pickup beam, along with other advantages afforded by an updated design. c. Old River Lock bulkhead installation. The site lost the capability to automatically latch and unlatch bulkheads when the 13,000 pound lifting beam was deleted to save weight. Without the lifting beam, workers are required to climb onto the bulkheads to connect the manual sling. Even with the manual slings the crane’s excess capacity is limited and exceeds the bulkhead weight by only 2,000 pounds. d. Lack of PLC Cut-off. There was no programmed PLC cut-off; therefore, the effect of overloads are not known. 7. INVESTIGATION ISSUES: The highest quality investigation results could not be achieved because of the lack of physical evidence including clear close-up photos of the wire rope failure. In the event of a future accident, it is recommend that all evidence be protected and made available until after the investigation is completed.

10

APPENDIX A PHOTO 1: EXISTING OLD RIVER LOCK CRANE

APPENDIX A PHOTO 2: BROKEN FLAT WIRE ROPE

11

APPENDIX A PHOTO 3: BULKHEADS DROPPED IN CHAMBER

APPENDIX A PHOTO 4: SECTIONS OF FAILED WIRE ROPE RETAINED ONSITE AFTER REMOVAL FROM WINCH

12

APPENDIX A PHOTO 5: SECTIONS OF FAILED WIRE ROPE RETAINED ONSITE AFTER REMOVAL FROM WINCH.

APPENDIX A PHOTO 6: NEW FLAT WIRE ROPE ONSITE NOT INSTALLED

13

APPENDIX A PHOTO 7: PORT ALLEN LOCK SIMILAR BULKHEAD LIFTING SYSTEM

LOWERING CARRIAGE

LIFTING BEAM AND BULKHEAD

WINCH AND FLAT ROPE WINCH AND FLAT ROPE

14

APPENDIX B: PORT ALLEN LOWERING CARRIAGE SIMILAR TO OLD RIVER LOCK

15

APPENDIX C: FLAT BRAID WIRE ROPE