Confined Spaces – Basic Rules of Safety
The following classic article was originally published in the January 1985 BULLETIN. A new introduction written by National Board senior staff engineer Robert Aben has been added.
Confined spaces come in many forms in and around pressure equipment. The following definition of confined space is from the US Department of Labor’s Occupational Safety & Health Administration, Regulations (Standards 29 CFR); Part 1910, “Occupational Safety and Health Standards;” subpart J, “General Environmental Controls;” standard number 1910.146, “Permit-Required Confined Spaces.”
"Confined space" means a space that:
(1) Is large enough and so configured that an employee can bodily enter and perform assigned work; and (2) Has limited or restricted means for entry or exit (for example, tanks, vessels, silos, storage bins, hoppers, vaults, and pits are spaces that may have limited means of entry.); and (3) Is not designed for continuous employee occupancy.
"Permit-required confined space (permit space)" means a confined space that has one or more of the following characteristics:
(1) Contains or has a potential to contain a hazardous atmosphere; (2) Contains a material that has the potential for engulfing an entrant; (3) Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor which slopes downward and tapers to a smaller cross-section; or (4) Contains any other recognized serious safety or health hazard.
Review of these two definitions reveals there is much involved to assuring a space is safe for entry; therefore, inspectors should not assume a confined space is safe to enter. Before entry, inspectors should ask the employer if procedures have been followed to ensure the space has been properly tested and is safe to enter.
Boiler inspectors (or anyone working around or entering confined spaces) should always use caution and follow all recognized safety rules. Complacency and apathy toward safety rules can be as dangerous as playing Russian roulette. Inspectors who regularly work in confined space can become so familiar with the conditions that they tend to let down their guards. Working conditions can be made very safe if inspectors remember to follow a few important, well-conceived safety rules.
Here are some basic rules:
- Before entering any boiler, lock out and tag all equipment items with movable parts connected to the boiler and fuel system. Place a sign at the operating controls indicating that a workman is in the boiler.
- Before entering any confined space, be certain it is properly isolated at all fuel, flue gas, steam, and water sources, and that it is properly vented. Obtain an air sample and check for breathing quality. Use low-voltage lights or explosion-proof flashlights inside the boiler.
- Notify the person in charge at the site when beginning the inspection and upon completion.
- Inspect with another person. If assistance is required, help will be close at hand.
- Always be aware of the nearest escape routes.
- Before closing drum manholes and furnace doors, it is essential to ensure all personnel are out of the boiler.
- Where possible, portable lamps of 12 volts or less should be used, with current supplied from transformers or batteries.
- Use only approved, properly guarded extension cords with waterproof fittings.
- All electrical connections should be made externally.
- Light fixtures should be equipped with explosion-proof guards.
- Sockets, light guards, and fittings should be properly grounded.
- If higher than 12 volt electrical power lines are used inside a boiler, all fittings should be provided with appropriate ground fault interrupters.
- All equipment used in confined spaces should be suitable for the environment to prevent explosion or ignition of combustible materials.
Additional safety precautions may be found in Part 2, Inspection, of the National Board Inspection Code. Failure to abide by these rules could be a shocking, painful experience.
Practice safety at all times; the life you save may be your own.