Performing Inspections in Confined Spaces

The hazards of confined spaces and the processes necessary to work in them safely are outlined

AWS Publications | February 8, 2021 | Inspection
Welding Digest ►  Performing Inspections in Confined Spaces

The hazards of confined spaces and the processes necessary to work in them safely are outlined

Inspectors in many industries have to enter a confined space from time to time, if not on a regular basis. A confined space may be defined as a space that has any or all of the following characteristics:

-Limited openings for entry and exit;

-Unfavorable natural ventilation;

-Not designed for continuous worker occupancy.

Confined spaces include, but are not limited to, boilers, pressure vessels, cargo tanks, fuel oil tanks, lube oil tanks, service tunnels, pump rooms, compressor rooms and engine crankcases. Some of the risks are as follows:

-Serious risk of fire or explosion;

-Loss of consciousness from asphyxiation arising from gas, fumes, vapor or lack of oxygen;

-Drowning arising from increased water level;

-Loss of consciousness arising from an increase in body temperature;

-Asphyxiation/suffocation arising from free-flowing solid (engulfment) or the inability to reach a breathable atmosphere due to entrapment.

 

Working in confined spaces is dangerous not only because of the reasons stated above but also because rescue from the confined space, in the case of an accident, is a difficult task in and of itself.

There are some precautions that can be taken to minimize the risk to property and human life. Before entering the confined space, it is always helpful to meet with the safety personnel and others in charge at the site. Getting to know the details of the confined space is very important to help you deal with unexpected situations that may arise during the inspection.

The American Welding Society (AWS) offers free PDF documents that provide clear help in addressing common safety and health concerns, such as the Safety & Health Fact Sheets. These include Fact Sheet No.11, Hot Work in Confined Spaces, for example. For more detailed information, refer to the free ANSI Z49.1 standard.

 

Organizational Procedure

 

Every organization must have a safety procedure for entering and working in a confined space (Figure 1). Before starting inspection work, get to know those procedures thoroughly. Spare the time to take training, if available. Familiarize yourself with the space, hazards related to the space, entry and exit procedures, rescue procedure and Emergency Action Plan (EAP).

Emergency and evacuation procedures should be agreed upon and understood by all parties involved in a potential rescue operation. Steps for safe rescue should be included in all confined space entry procedures. Rescue should be well planned and evidence should be made available that indicates drills have been frequently conducted on emergency procedures.

Fig. 1Figure 1: Signs such as this warn of a confined space area and should be part of the organization’s safety procedures.

 

Entry Certification

 

In many situations, certification by a qualified person is required before personnel may enter a confined space. Whenever there is a requirement for certification, anyone who is not certified, no matter how much experience they might have in similar situations, must not enter and commence work.

 

The Permit

 

Entry into permit-required confined spaces must comply with regulations promulgated by the Occupational Safety and Health Administration. These regulations include developing a written program, issuing entry permits, assigning attendant(s), designating entrants and ensuring a means of rescue. In other words, the permit should

-Identify the nature of work to be done, exact location and precautions taken or to be taken;

-State safe working procedure;

-Provide written authority for the confined space to be entered and the work to start, and the time when the work must cease;

-State the time slot allocated for the designated work;

-Identify the personnel entering the space and verify they have received the required training.

 

Entry into a confined space should only be allowed when a separate permit has been issued verifying tests have been taken to ensure the atmosphere is safe to breathe.

All valves leading in or out of the confined space should be clearly marked “do not operate” (Figure 2).

Fig. 2Figure 2: Warning sign for a valve leading in or out of a confined space.

 

Testing the Atmosphere

 

Never trust your own senses to determine whether the air in a confined space is safe! Many toxic gases and vapors can neither be seen nor smelled, nor can the level of oxygen present be determined without instrumentation. Proper procedures must be established to verify that the atmosphere is safe to work in or if some special respiratory equipment is needed.

 

Effect of Work Performed

 

The type of work performed is also important because toxic atmospheres are generated in various processes. For example, solvents are used in many industries for cleaning/degreasing. The vapors from these solvents are very toxic in a confined space. Operations such as welding, cutting, and brazing produce high heat that consumes oxygen. Painting, scraping, sandblasting, and degreasing generate dangerous gases and/or vapors. As you can see, the atmosphere in a confined space, which may be safe at the time of entry, can become toxic after the work has begun.

 

Personal Protection Equipment

 

Use of proper personal protection equipment (PPE) is very important. You should not only have the proper PPE, but also know how to use it. Some common types of PPE are as follows:

-Body protection (hard-wearing overalls with suitable pockets for notebook, etc.);

-Foot protection (steel toe caps, steel midsoles, good grip, oil resistant);

-Head protection (hard hat with chin straps);

-Hand protection (hard-wearing gloves);

-Eye protection (protective glasses, goggles);

-Ear protection (earmuffs or earplugs, which may need to be worn with a communication system);

-Gas meter (a multigas meter for measuring HC, H2S, CO, O2 is recommended) — (Figure 3);

-Lighting (hand-held with lanyard and appropriate beam width);

-Special equipment as needed, i.e., explosion-proof lighting, special breathing apparatus.

Fig. 3Figure 3: Example of a meter for measuring a variety of gases.

 

Care also must be taken to not carry too much material such as extra drawings, notebooks, unnecessary PPE, etc., because these may cause a problem if a rescue is necessary as well as they could restrict your movement in a confined space. Carry only what you need, nothing more.

 

Lighting and Ventilation

 

A dark confined space is even more dangerous to work in, so ensure a proper level of lighting in the work area. Ensure the electrical connections provided to the lights are properly insulated so as not to cause explosion or fire. The type of light should be suitable for the type of work being done. A 60-W bulb cannot be provided for painting work being carried out in a confined space, an explosion-proof light is required.

Ventilation is also a major factor in this case (Figure 4). Ensure proper arrangement of ventilation or blowers. Table 1 shows the health effects created by varying levels of oxygen. Lack of oxygen can lead quickly to unconsciousness and death.

Fig. 4Figure 4: Ensure proper arrangement of ventilation or blowers.

 

Standby/Rescue

 

A person should never enter a confined space without a rescue person standing by (Figure 5). A standby person should always be available at the entry of the confined space to ensure the worker’s wellbeing. The standby person

-Should not have any duties other than to serve as standby and know who to notify in case of emergency;

-Should never leave his or her post even after help has arrived. The standby person is also a key communication link to others onboard;

-Rescuers must be trained to follow established emergency procedures and how to use appropriate equipment and techniques (such as lifelines, respiratory protection, and serve as standby persons).

 

Fig. 5Figure 5: Diagram showing the positioning of the standby person when work is being done in a confined space.

 

Table 1: Health effects from lack of oxygen

O2 level           Effects

22%                 Oxygen-enriched atmosphere

20.8%              Normal level. Safe for entry (± 0.2%)

19.5%              Oxygen-deficient atmosphere

16%                 Impaired judgment and breathing

14%                 Rapid fatigue and faulty judgment

11%                 Difficulty breathing and death in a few minutes   

 

This article was written by Peter C. Amin for the American Welding Society.