R 408.41483 Caissons used under pressure.

Rule 1483. (1) A caisson used under pressure shall be subjected to a hydrostatic test equal to 200% of the working pressure before being used on a job, at which pressure it shall be tight. The caisson shall be stamped on the outside shell about 12 inches from each flange to show the pressure to which it has been subjected. (2) All caissons that have a diameter or side greater than 10 feet shall be provided with a man lock and shaft for the exclusive use of employees. In addition to the gauge in the locks, an accurate gauge shall be maintained on the outer and inner side of each bulkhead. These gauges shall be accessible at all times and kept in accurate working order. (3) In caisson operations where employees are exposed to compressed air working environments, employers shall comply with Occupational Health Standard Part 665 “Underground Construction, Caissons, Cofferdams, and Compressed Air,” as referenced in R 408.41410.