Keywords: Trench safety - warped welded end link 2 (9250657724).jpg An instructor comparing a safe welded end link left to an unsafe stretched link right https //www flickr com/photos/niosh/9250657724/ Trench safety - warped welded end link 2 2010-03-17 11 17 https //www flickr com/people/25069384 N03 National Institute for Occupational Safety and Health NIOSH from USA PD-USGov NIOSH http //flickr com/photos/25069384 N03/9250657724 2015-04-23 18 50 23 United States Government Work Construction Safety Shoring Work Workplace National Institute for Occupational Safety and Health |