The following guidelines can help you be more proactive in minimizing hazards and keeping workers safe in confined spaces.
Know the standard
A confined space has limited means of entry or exit and is large enough for a person to enter to perform work, but is not designed for continuous capacity.
OSHA standard 1910.146 covers terminology, general requirements, duties of each person involved in a confined space project, training, and rescue and emergency services. The standard will also help you determine whether a site is a permit-required confined space. A permit-required confined space has one or more of the following characteristics:
• Contains or has the potential to contain hazardous atmosphere
• Contains a material that has the ability to overcome an entrant
• Contains an internal design where a worker could be trapped or asphyxiated by inwardly converging walls or by a floor that slopes downward and narrows to a smaller cross-section
• Contains any other recognized serious safety hazard, such as a fall hazard
Recognizing a permit-required confined space will help with adequate planning, training procedures, and procuring the equipment necessary to keep employees safe.
The next step is to develop and implement a safety program for each permit-required confined space that complies with the standard. Safety managers should also offer employee training on confined space entry and proper personal protective and/or fall protection equipment.
Fall arrest systems for confined space entries should include an anchor, connector and harness. Choose a system based on the type of work and particular environment. Anchorage options can include:
• Tripods: Tripods are ideal for manhole entry and retrieval applications because they are typically lightweight, portable and can be easily set up by one worker. Tripods are limited, however, in the size of the manholes they may be able to accommodate.
• Davit arms or davit posts: An alternative to the basic tripod, davits have a variety of base configurations that make confined space entry possible. Some have adjustable bases to accommodate the worker over large openings; others are fixed in a V-shape and placed adjacent to the openings. Davit bases can be portable and offer a fixed position.
• Counterweight systems: A counterweight system uses weights to provide a sturdy support structure to offset the weight of a worker. They are useful when a confined space does not allow the legs of the tripod or davit arm to be placed adjacent to the opening.
• Side-entry system: The side-entry system is designed for confined space entry/retrieval and rescue operations involving horizontal entries with vertical positioning required inside the space. The system clamps or bolts to the side of a tank to provide an anchorage point and base for attaching a winching mechanism.
Develop a confined space entry rescue and retrieval plan before working in any confined space. The plan should identify all potential hazards and related rescue scenarios. Confined space deaths often happen during rescue situations because rescuers are put at considerable risk. There are three categories of confined space rescue:
• Self-rescue: Although not always possible, self-rescue is always the fastest and safest option. When a worker senses danger, he/she should remove themselves from the space immediately.
• Non-entry rescue: This method involves another worker but without having anyone else enter the confined space. For example, a winch line can be attached to the person in the confined space. Non-entry rescue is required unless a feasibility study was done proving that non-entry rescue will create a greater hazard to entrants.
Entry rescue: Entry rescue should be a last resort and only used if self-rescue and non-entry are impossible. A trained worker(s) will enter the confined space to rescue the trapped person. Entry rescue workers are put at considerable risk and should wear proper fall protection equipment, such as a full-body harness connected to a winch and davit system. Make sure the rescuer is trained on the proper respiratory protection for entry rescue.
Workers should know the plan and be properly trained for confined space rescue. The most effective training sessions have a good mixture of classroom and hands-on training. Equipment manufacturers offer on-site training courses on how to properly use equipment and implement effective rescue plans. Training experts offer specialty programs to train workers to be attendants, entrants, supervisors and rescuers.