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by Mark B. Geiger, M.S.E., CIH, CSP, Arlington, Virginia
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Risk Review and Management Approaches in the Maritime Industry
Shipyards are among the most hazardous U.S. industries, with a non-fatal injury rate of 22.0 per injuries and illness per 100 full-time workers (BLS data for 2000) compared to a general average of 6.1 per 100 for private industries6. Ship construction and repair operations have a significant range of fall hazards that contribute to these statistics and to the total risk inherent in ship maintenance and construction.
The National Shipbuilding Research Project (NSRP) [Ref. 5] reviewed falls in shipyards addressing both falls from height and at the same level. The evaluation considered engineering and procedural approaches to reducing risks. Participants included eight shipyards. Falls represented approximately 20% of total injuries and 30% of lost-time injuries.
Statistics in the United Kingdom are similar. Review of records from 2001/2002 indicate that shipyard falls from height account for 23% of serious injuries (defined as three or more days away from work). Slips, trips and falls at the same level accounted for 25% of such mishaps [Ref. 6].
Data provided privately by a large American shipyard (Table 2) demonstrates the relative proportion of falls occurring at both the same level and from height. Direct compensation and medical costs for "simple" injuries involving back, knees or other individual injuries were reportedly in the range of $20,000 per event. Those involving multiple injuries, such as back and shoulder, cost in the range of $30,000.
The NSRP data identifies the location of falls and their general common causes and recommends control measures. Losses associated with these injuries were estimated to account for direct costs in the range of $25.2 million, with indirect costs of approximately $100.8 million, for a total loss of $134 million [Ref. 5].
Table 2: Review of Falls in a Major American Shipyard
| Category of fall | Fraction of falls* |
| Falls at same level (slip-trip-fall) | 54% |
| Fall through opening or other space | 24% |
| Fall from ladder or scaffold | 19% |
| Fall between different levels | 16% |
| Falls on stairs/steps | 9% |
| * (Does not equal 100%. Some categories overlap.) |
A high fraction of these mishaps were influenced, and might be controlled by, factors associated with good engineering design and effective process management.
Case Study of Aircraft Carrier Deep Tanks
The Environmental Protection Integrated Process Team (IPT) for the Future Aircraft Carriers Program conducted a special study of fall hazards in aircraft carrier storage tanks. The design of deep tanks and voids on large vessels can create intrinsically hazardous environments, combining fall hazards in locations with potential confined space atmospheric hazards, restricted access and typically poor illumination. Shipboard space limitations contribute to tank location in areas that are otherwise difficult to use, such as along the side of a steeply sloping hull. Many tanks and voids are irregularly shaped because of the hull configuration. Impediments to safe and efficient access include small manholes (top entry ports), passage through bulkheads provided by narrow elliptical swash holes as little as 15-inch minimum diameter, footholds limited to "D-hole" penetrations in transverse bulkheads, minimal anchorage points for hoisting, scaffold erection and the securing of personal fall arrest equipment; and irregular space configurations, such as steeply angled bases. Shipyard workers report the irregular placement of D-ring holes in certain tank locations with distances as great as three feet between the tank inner bottom and the first climbing point.
The Safety Branch (Code 106) at Puget Sound Naval Shipyard (PSNS) acts as the lead shipyard for fall protection in the Navy. Its earlier evaluation concluded that D-hole footholds in the transverse bulkheads, used for access into the hull's infrastructure (in wing deep tanks and voids), did not qualify as either safe or acceptable ladders since they did not provide any fall protection7. PSNS initiated measures to provide assured fall protection that includes development of an anchorage assembling that fits into D-ring holes and provides an assured anchorage, erection of scaffolding inside many tanks undergoing repair or maintenance; and requirement for fall protection to be used in all jobs conducted at elevation, with the potential exception of the "first man up" in certain situations. PSNS also provides worker training that includes practice inside a mock-up of a carrier deep tank.
The anchorage assembly for scaffolding and personal fall protection has not been widely used outside PSNS. Other facilities are reportedly reluctant to erect scaffolding inside tanks because of the additional labor costs.
Current configurations were reviewed with reference to recommended criteria for human systems integration [Refs. 7, 8].
Evaluation of existing configurations, approaches to installing scaffolding and secure anchor points developed by Puget Sound Naval Shipyard and discussion with workers and technical experts suggest that relatively minor changes might reduce the risk of entry and improve access8 [Ref. 9].
6 Shipyard work has generally been reported as the second most hazardous work setting in the U.S., second only to commercial fishing.
7 Vertical ladders more than 15 feet high are required to provide fall protection, typically through a climber's safety rails or ladder cages.
8 Recommended changes were developed with the intent of limiting the extent of modifications necessary to layout of new designs. Any such change to existing designs or new structures requires the involvement of Naval architects and professional engineers to evaluate potential impact on structural integrity, stability and stiffness, and other critical design parameters.
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