33 CFR 142.84: Housekeeping.

All staging, platforms, and other working surfaces and all ramps, stairways, and other walkways must be kept clear of portable tools, materials, and equipment not in use and be promptly cleared of substances which create a tripping or slipping hazard. When engaged in an activity on the drill floor in which the spillage of drilling fluid is inevitable, such as when pulling wet strings of drill pipe, footwear and flooring designed to reduce slipping substantially may be used instead of keeping the drill floor free of drilling fluid during the activity.