Hidden hazards associated with wall/floor/ceiling penetrations
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Type:  Lessons Learned

Publisher:  National Aeronautics and Space Administration, Kennedy Space Center, Cape Canaveral FL

Published As:  Public

Date: 

Topics:  Occupational Safety and Health, Operations, Maintenance, Work Management/Planning

The Center was in the process of upgrading one of its buildings when some of the actions being taken by plumbing personnel resulted in a close call. A sub-contracted pipe-fitter was drilling holes in the concrete floor of the building in preparation for the installation of a gas panel. As the drill bit was passing through the concrete, the back pressure on the drill increased. In response, the pipe-fitter withdrew the drill bit and replaced it with one that was appropriate for rebar, since he believed the rebar to be the cause of the increased back pressure. With the new drill bit installed the pipe-fitter resumed drilling. However, shortly thereafter, water began to backfill and drain out of the drill hole. At this point the pipe-fitter stopped his work and notified building personnel. The building personnel halted the remaining part of the job to investigate the source of the water.

The immediate investigation was able to determine that a conduit housing both water pipes and three potentially lethal energized 480V AC electrical conductors was breached by the drill bit. Consequently, work was stopped, the job site secured, and measures were taken to safely complete the job.

Lessons Learned: Using out of date or unintelligible building drawings to guide potentially hazardous work is comparable to not consulting any drawings at all. This practice actually increases the risk of exposing personnel to hazards since the work is unjustifiably considered to be safe or controlled. Consequently: a. A hazard analysis should be performed when a standard control is compromised or suspect. Critical safety requirements and processes may be undermined and overlooked if they are placed in the appendices of a document, they do not provide sufficient implementation details, or if they reference non-existent documents. Halting a penetration operation and investigating it when there is a change in backpressure or ejection of an unexpected material is a good practice that can prevent a serious injury.

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