Potential Confined Space Hazards

Always ventilate spaces with normal air and never pure oxygen. Introducing a source of ignition into a space containing a flammable atmosphere will cause an explosion. Consider hazardous most liquids, vapors, gases, mist, solid materials, and dusts space. 

All welding and cutting operations carried on in confined spaces must take place with adequate ventilation to prevent the accumulation of toxic materials, possible oxygen deficiency, or explosive atmosphere. 

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The chemical release into a confined space is life threatening. High-pressure liquid, falling objects, and slippery surfaces in a confined space are all potential hazards. The limited space, inadequate ventilation and light, and excessive noise are also physical hazards that increase the confined space hazards. The chemical waste and useful chemicals are also life threatening. 

General industry and the construction industry have a lot in common when it comes to confined space hazards the potential for fire, explosion, chemical exposure and oxygen enrichment or deficiency. In spite of the commonalities, there are significant differences between the two, says Edward J. Willwerth, an NFPA-certified marine chemist who has taught confined space safety courses for the U.S. military, shipyards, petroleum terminals, chemical manufacturers and industrial facilities. 

F. All site control elements of the safety and health program must be fully implemented as described in the program. The purpose of site control requirements is to ensure that only properly trained and authorized individuals enter those areas of the site with potential hazards, and that, in the event of an emergency, rapid assistance can be rendered to employees working in the exclusion zone. This section discusses the findings of two components of site control the establishment and maintenance of site work zones and the establishment and implementation of appropriate confined space procedures. 

Contract employees must perform their work safely. Considering that contractors often perform very specialized and potentially hazardous tasks, such as confined space entry activities and nonroutine repair activities, their work must be controlled while they are on or near a process covered by PSM. A permit system or work authorization system for these activities is helpful for all affected employers. The use of a work authorization system keeps an employer informed of contract employee activities. Thus, the employer has better coordination and more management control over the work being performed in the process area. 

An assessment of each element of the program of work is carried out using the Assessment of Potential Hazards Form APHl (see below), which is to be completed by the person responsible for the task to be carried out. This may include hot work cutting/grinding work on electrical systems working alone use of hazardous materials (e.g. chemicals, solvents, etc.) confined spaces or any other work which may be of a hazardous nature. 

Potential sources of carbon monoxide hazards include metal-refining processes, in which it is formed as a byproduct and used as a fuel (LEL 12.5%), and running vehicle engines (particularly petrol-driven) or gas-fired heaters in poorly ventilated confined spaces. It is also a feedstock in the manufacture of a variety of chemicals, e.g. methanol, acetic acid, phosgene and oxo-alcohols. 

A brief example helps If I have ajar containing gasoline it is a potential explosion hazard, or is it If the jar is sealed vapor tight, where s the hazard Now take the eap off the jar Is there a hazard If so, to whom The air blowing aeross the jar and the vapor pressure of the liquid will cause it to evaporate. Again, no problem — maybe or maybe not. However, if we are in a confined space with an source of ignition, there may be an explosion. Similarly, if the container falls off the shelf and releases the gas, there is an additional hazard which may lead to fire or explosion. 

Maintenance must sometimes be performed at elevated heights, within confined spaces, and in situations with challenging ergonomic conditions. Opening equipment that has not been properly prepared may have potential to release chemicals or electrical or mechanical energy. Hazards that exist in other parts of the process could be transported to areas where maintenance is underway, if the systems have not been suitably isolated or fully cleared of residual chemicals. 

Metallic mercury is mostly a problem in confined spaces or where it is handled in industrial processes or in laboratories. It is not generally an environmental problem, more likely an industrial hazard. However, metallic mercury does occur naturally (it was mined in Spain and Slovenia, for example) and the use of mercury for metal reclamation is a potential environmental hazard in countries such as Brazil where miners use it to extract gold from river sediments. Inorganic and organic mercury may be produced from the metallic mercury during its use and subsequent release into the environment. 

Nitrous oxide is purchased in cyhnders containing 15,000 htres which provides some 12 hours of operation of an N2O/C2H2 flame. When removed from the tank at 15-20 L/min expansion of the gas in the pressure regulator can freeze the diaphragm rendering it inoperative. Heated regulators for N2O are recommended for AAS applications. As with C2H2, a portion of the N2O in the cylinder is liquefied so that the drop in head pressure with consumption will not be hnear. The areas where this gas is stored or used shoiild be well ventilated as this gas is an asphyxiant and a potential hazard in a confined space. 

Pyrotechnically generated smokes from grenades or powder clouds may not be acceptable from a safety point of view in certain circumstances for example, where fires may be produced, or in confined spaces with low rates of ventilation where asphyxial effects could develop. In order to reduce such potential hazards, a variety of approaches have been investigated. One of these is the use of highly volatile PCSI materials, which can be projected into enclosed spaces, but no material of sufficiently low toxicity has yet been found which is acceptable. An alternative approach is the use of a PCSI substance dissolved in a volatile solvent, and the mixture projected into the area by means of a pressurized aerosol canister or a frangible missile. This results in the development of an airborne vapor or aerosol of irritant (Ballantyne, 1979). 

Hazard identification. All suspected conditions that may pose inhalation or skin absorption hazards that are immediately dangerous to life or health (IDLH) or other conditions that may cause death or serious harm shall be identified during the preliminary survey and evaluated during the detailed survey. Examples of such hazards include, but are not limited to, confined space entry, potentially explosive or flammable situations, visible vapor clouds, or areas where biological indicators, such as dead animals or vegetation, are located. 

Asphyxiation Asphyxia or suffocation. Asphyxiation is one of the principal potential hazards of working in confined spaces. 

Confined Space any space not intended for continuous human occupancy and having a limited means of egress. A permit-required confined space contains or has the potential for a hazardous atmosphere (toxic, flammable, or oxygen deficient) and/or engulfinent or entrapment hazards. Confined or enclosed spaces include, but are not limited to, storage tanks, process vessels, bins, boilers, ventilation or exhaust ducts, sewers, underground utility vaults, tunnels, pipelines, and open top spaces more than 4 feet in depth such as pits, tubs, vaults, and vessels. 

Contract employees must perform their work safely. Considering that contractors often perform very specialized and potentially hazardous tasks such as confined space entry activities and nonroutine repair activities, it is quite important that their activities be controlled while they are working on or near a covered process. 

Maintenance work is, by its very nature, hazardous. Workers maintain equipment that is opened or disassembled, thereby exposing those workers to a wide range of potential hazards that stem from toxic chemicals, heat, electricity, moving machinery, hydraulics, pneumatic equipment, falling objects, springs and coils, and falls from equipment. In addition, maintenance workers may be asked to work at heights, in confined spaces, or in other unsafe locations. Therefore, first goal of any maintenance procedure is to ensure that the work can be carried out safely. 

The second definition is a subset of the first. A permit-required confined space is a confined space with one or more of the following characteristics contains or may contain a hazardous atmosphere, contains a material with the potential for engulfment of an entrant (such as sawdust, sand, grain, or earth), has an internal configuration or shape such that an entrant could be trapped or asphyxiated, or contains any other recognized serious safety or health hazard. 

The criterion for permit-required confined space is that it contains or has a known potential to contain a hazardous atmosphere, including chemicals, sludge, or sewage. Hazardous atmosphere means an atmosphere that may expose employees to the risk of death, incapacitation, impairment of ability to self-rescue (escape unaided), injury, or acute illness. Examples of hazardous atmospheres are a flammable gas or vapor, airborne combustible dust at a concentration that meets or exceeds its LEL, unacceptable oxygen levels, or any atmospheric condition recognized as immediately dangerous to life or health (IDLH). 

All hazards are not addressed by the unwanted energy release concept. Examples are the potential for asphyxiation from entering a confined space filled with inert gas, or inhalation of asbestos fibers. But aU hazards are encompassed within a goal that is to avoid both unwanted energy releases and exposures to hazardous environments. Many authors have recognized the importance of Haddon s writings. 

Not everyone — in fact relatively few workers in total — enter confined spaces. Or work in trenches or on roofs. Operate potentially hazardous machinery. Many more employees take to the highways. 

Before conducting work that involves confined space entry, work on energy systems, and ground disturbance in locations where buried hazards may exist, or hot work in potentially explosive environments, a permit must be obtained that ... 

A space that by design has limited openings for entry and exit, unfavorable natural ventilation, contains or produces dangerous air contaminants, and is not intended for continuous employee occupancy. Occupational Safety and Health Administration (OSHA) uses the term permit-required confined space (permit space) to describe a confined space that has one or more of the following characteristics contains or has the potential to contain a hazardous atmosphere contains a material that has the potential to engulf an entrant has walls that converge inward or floors that... 

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