Weld Inspection in Confined Spaces
Despite the hazards, confined space entries can be performed safely if they are evaluated carefully, proper equipment is at hand, and guidelines are followed.
SOURCE: American Welding Society
Weld Inspection in Confined Spaces
Despite the hazards, confined space entries can be performed safely if they are evaluated carefully, proper equipment is at hand, and guidelines are followed
BY CYNTHIA W. DUFFIELD AND KRIS BANCROFT
Work in confined spaces poses special hazards, but with proper planning, good equipment, and knowledge of the possibilities, weld inspections can go smoothly and without injury. You need to understand the fundamentals of confined space work, know what equipment is needed to perform the inspections, and follow routine guidelines for entering, working in, and exiting confined spaces. You should also know when to refuse to enter.
First, however, you need to know what constitutes a confined space. Keep in mind the following:
- A confined space is large enough and so configured that an employee can bodily enter and perform assigned work. It 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.
- It is not designed for continuous employee occupancy.
You don't hear a lot about deaths in confined spaces. But believe us, entering a permit-required confined space is one of the most dangerous jobs you may ever do. Entering a confined space supervised by someone who doesn't know what he or she is doing is like getting into a car with a drunk driver who claims he's done this lots of times and "no one's been hurt yet."
Why Is Entering a Confined Space So Dangerous?
Things happen fast in a confined space. Oxygen is used up or displaced. Flammable vapors increase rapidly. Toxic vapors can't dissipate easily. It's usually hard to get in and out, and you're out of view. It may be difficult to see and hear. Sometimes there are machines or chemicals that need to be locked out, bled, and/or blanked.
An employee tests for oxygen first, then percent lower explosive limit (LEL). Entrants have the opportunity to observe.
Because of the high risk of death from these hazards, the Occupational Safety and Health Administration (OSHA) published the standard 29 CFR 1910.146, Permit-Required Confined Spaces. This standard only applies to general industry; the construction and maritime industries also have confined and enclosed space regulations that must be followed. To keep your skin whole, however, we recommend you follow 29 CFR 1910.146.
Who Must Comply with Which Regulations?
If an employer has control over a confined space (i.e., it's part of the facility or contract), the employer must address the hazards. If employees enter any confined space, the employer must comply with additional requirements. A permit-required confined space or permit space is a confined space that has one or more of the following characteristics:
- It contains or has a potential to contain a hazardous atmosphere; It contains a material that has the potential for engulfing an entrant; It has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor that slopes downward or tapers to a smaller cross section;
- It contains any other recognized serious safety or health hazard.
As mentioned previously, OSHA's Permit-Required Confined Spaces Standard, 29 CFR 1910.146, applies to general industry. Several standards, including 29 CFR 1926.21, cover confined space entry in the construction industry. In 29 CFR 1926.21, employers are required to instruct employees who enter confined or enclosed spaces regarding the hazards, necessary precautions, and use of protective and emergency equipment. Maritime standards also address the hazards of confined and enclosed spaces. In some ways, the maritime standards for confined space entry are more specific than the general industry standards. Subpart B of 29 CFR 1915, Confined and Enclosed Spaces and Other Dangerous Atmospheres in Shipyard Employment, requires spaces be visually inspected and tested by a competent person. (See 29 CFR 1915.7 for competent person qualifications.) What Went Wrong?
Let's look at some confined space accidents and what went wrong. These are real cases. You can find more of them by looking on the OSHA Web site (www.osha.gov) under "Statistics" and then "Accident Investigation Search." Example 1. Two employees prepared to inspect a heat-treating vessel. One of them wanted to get the right personal protective equipment and a permit. The second one said he wasn't going to do the paperwork for such a short job. The first employee removed the vessel lid with a hoist while the second put a ladder in the vessel and entered. When the first employee turned around, he saw the other employee trying to climb up the ladder then fall to the bottom of the vessel. The first response team was called and, using the hoist, removed the victim within four minutes. They began CPR, continuing until relieved by the ambulance crew. The victim was taken to a hospital where he was pronounced dead of argon asphyxiation. The atmosphere in the space was tested and found to contain 5.2% oxygen.
If they'd tested the atmosphere, the employee wouldn't have entered unless he was wearing a self-contained breathing apparatus (SCBA) or the vessel had been ventilated until the oxygen was above 19.5%.
The entry supervisor signs the permit after atmospheric testing results are recorded and rescue service is verified.
Example 2. Employees were repairing a fuel leak in an aircraft wing. They used methyl ethyl ketone (MEK), a scraper, and a handheld vacuum to remove old sealant. They later discovered one of the employees unconscious in the interior right main tank of the aircraft wing. His coworkers tried to remove him from the wing but were unsuccessful. The fire department arrived and, after several attempts, the victim was retrieved. The paramedics couldn't revive him. He was wearing a half mask respirator with organic chemical cartridges.
1) The concentration of a volatile solvent in a confined space will increase rapidly. The space can reach IDLH conditions (immediately dangerous to life and health) in a short time. The atmosphere should have been continuously monitored and employees removed when the atmosphere became toxic. 2) There should have been an attendant monitoring all entrants. 3) The employer should have provided the fire department access to permit spaces where rescue may be necessary so the fire department could develop a rescue plan and practice rescue operations. Example 3. Two employees were cleaning out a process water tank using an air pump. Carbon disulfide was discovered in the flow meter that measures water moving from the tank to the reactor. Contaminated water from the area surrounding the carbon disulfide bulk storage tank had been pumped into the process water tank. One employee used a water hose to keep down sparks. He had a flashlight and a drop light to see inside the process tank. The employees smelled carbon disulfide, but no measurements were taken despite its flammability. The water for cleaning had been turned off and on again at a pump when there was a flash and then a fire. The first employee sustained second-degree burns over 35% of his body and third-degree burns on his shoulders and arms. 1) The atmosphere should have been monitored for a flammable atmosphere. 2) Intrinsically safe lights and nonsparking tools should have been used. Example 4. An employee was assigned to inspect the interior of a new railroad tank car. He and his attendant followed the company's confined space program by getting a permit and an oxygen/lower explosive limit (LEL) meter. They put the meter on a broomstick and waved it around inside the tank, listening for an audible alarm. Then they brought the meter out into the outside air and took the oxygen reading, which was 20.8%. The employee entered the tank car with no respiratory protection. He was unconscious in less than a minute. The attendant called another employee who also went in and passed out. A third employee tried to enter, became dizzy, and had to be helped out. The local fire department arrived with SCBAs and rescued the first two employees. The first employee died and the others were hospitalized. The car contained a nitrogen blanket to inert the atmosphere. 1) If the atmosphere had been tested correctly, the employees wouldn't have entered. 2) If the first employee was wearing a harness and rescue line, the other employees could have performed a nonentry rescue. Example 5. Three employees, an electrician, a recovery foreman, and an instrument mechanic, were assigned to work on a recovery boiler precipitator at a pulp and paper mill. The precipitator had a grounding problem. The instrument mechanic ran a gas test for oxygen, hydrogen sulfide, flammability, and mercaptans. The test results were negative, and a confined space permit was issued. Although the recovery foreman had authorized the permit, the precipitator had not been de-energized and locked out. The electrician entered the confined space and was electrocuted when he contacted an exposed energized part of the 51-kV DC precipitator.
Lockout/tagout of hazardous energies such as electricity should be part of the permit-required confined space entry and should be included on the permit.
Chemicals, water, and steam must be locked out in addition to electrical systems..
Typical Problems with Confined Space Programs
As an inspector, you may be called upon to enter a confined space that's controlled by another company. Although that company may have a permit-required confined space program, don't trust your life to just any program. Even if permits are used, know how to detect an inadequate program. Check to see if any of the following conditions apply.
- Inadequate atmospheric testing equipment such as no equipment, equipment not calibrated, or the equipment doesn't measure an important hazard. Inadequate attendant. Is there no attendant, one who checks "occasionally," or one who is untrained? Has the attendant been given the job as a form of discipline? Inadequate rescue service. This could mean no rescue service selected, the rescue service has not seen the permit space, or the time for rescue response is too long. It could also mean no harness, lifeline, or mechanical device is available to retrieve personnel.
- Inadequate lockout/tagout. The company may have no lockout/tagout program or it may lock out some sources of energy, such as electrical, but neglect others, such as chemical, pneumatic, and hydraulic, or each entrant does not have the opportunity to put his or her own lock on each disconnect.
When preparing to work in a confined space, don't take anything for granted. Be sure to ask questions such as the following:
- When was the direct-reading instrument (gas meter) last calibrated? Who provides rescue service for your entries? How long does it take for the rescue service to arrive at your location? When was the last time the rescue service practiced a rescue operation?
A word of caution: Don't go in a permit-required confined space if any of the following conditions are present.
There is no signed permit (1910.146(c)(5)(ii)(H)). You don't see the atmosphere tested at least at the top, middle, and bottom of the space. (You have the right to observe the preentry testing [1910.146(c)(5)(ii)(C)].) Oxygen is below 19.5%, LEL is above 10%, carbon monoxide is above 50 ppm, or hydrogen sulfide is above 20 ppm. (Be suspicious if the readings approach any of these values because they can change quickly.) Mechanical or electrical equipment that could start up has not been locked out. (While there is no requirement for each entrant to place his or her own lock/tag on each disconnect and to pocket the keys, that is one option. The company can also have a good group lockout program. However, every entrant must be given the opportunity to verify isolation and attach a personal lock/tag to the group lockout device (1910.147).) You don't have a harness and rescue line (1910.146(k)(3)(i)). There is no attendant (1910.146(d)(6)). Solvents or paint is in use or curing unless there is monitoring for the specific solvents. (Flammability testing isn't good enough. IDLH concentrations are usually below the detection limit of a meter that measures flammability.) An internal combustion engine is operating nearby and carbon monoxide is not monitored. Rescue service has not been notified of the entry. (The entry supervisor is required to verify rescue service is available and the means for summoning it works [1910.146(j)(4)].)
- A person is in trouble and you don't have rescue training and equipment. (More people die attempting to rescue others from a confined space than do the original entrants.)
If you enter confined spaces in a number of different facilities, we suggest you or your employer invest in the following equipment. Don't make the mistake of doing without important equipment because the host employer doesn't have it available.
- Four-gas meter and calibration gases Harness, retrieve line, and connectors Intrinsically safe flashlights Several padlocks, hasp, chain, and tags for lockout/tagout
We don't recommend you buy a respirator because it can give you a false sense of security. If the atmosphere is not acceptable, insist forced ventilation be used and continue the ventilation during your confined space entry.
Permit-required confined space entries can be done safely if you evaluate each entry as a new confined space. Hazards can change rapidly. Follow a permit system. And never enter a permit-required confined space if you have any thoughts that things are not quite right.v
CYNTHIA W. DUFFIELD (firstname.lastname@example.org) is Safety and Occupational Health Manager, U.S. Geological Survey, Reston, Va. She is a Certified Industrial Hygienist, Certified Safety Professional, and Certified Quality Engineer. KRIS BANCROFT (email@example.com) is President, Tiger Safety Consultants, Dayton, Tenn. He is a Certified Safety and Health Manager.
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