Hot Work

9/24/2018

Hot work: this term encompasses activities that involve burning, welding, or using fire or spark-producing tools.  Such tasks include welding, torch cutting, brazing, soldering and grinding. And persons performing these activities are exposed to risks of fires from ignition of flammable or combustible materials within the work space as well as flammable gas leaks, burns from physical contact with hot surfaces and eye injuries from visual exposure to UV light.  When hot work is performed in a confined space environment, serious consequences due to oxygen depletion, explosive atmospheres and inhalation of airborne contaminants can result. 

The more obvious hazards associated with hot work include fires and explosions, which in turn, can lead to serious injuries. Therefore, hot work needs to be performed in locations that are away from fire hazards. Such hazards include flammable vapors or combustible materials.  It is prudent practice to keep such flammable materials as volatile organic solvents (alcohols, ketones (acetone), ethers (MEK), and glycol ethers) at least 35 feet away from any hot work. That’s because these materials have extremely low flash points and even the smallest of sparks can ignite these solvents, causing a fire that could instantaneously cause a work area and even a building to be engulfed that would be too great for fire-fighting measures to be effective! While 35 feet is an OSHA requirement (29 CFR 1910.252(a)(2)(iii)(A)) for a safe distance from hot work, it is always important to ensure sparks and slag do not come near flammables – no matter how far they may originate from a work location.

While the term combustible is no longer defined by OSHA (per the recent Hazard Communication Standard (29 CFR 1910.1200 – Haz Com 2012 per adaptation of the UN globally harmonized system), “combustible” is still a term used for transportation (DOT regulations) and environmental (EPA – RCRA) activities. OSHA now classifies such materials as Flammable Category 4 (with a flash point greater than 140º F). Nevertheless, combustible material (or category 4 flammables), can still catch fire and can propagate rapidly.  For instance, a fire that initiates in a typical 2-story house will be completely engulfed (when no firefighting equipment is used) in less than five minutes! 

Using guards or non-porous barriers may also be considered as they can control the heat, sparks, and slag from reaching beyond the immediate work area.  Guards may be necessary as hot work may be required in some areas where flammables and combustibles cannot be relocated (such as in a refinery where large tanks exist) and therefore the ability to move flammables/combustibles a safe distance from hot work may not be feasible.

Whenever hot work is being conducted, it is important that appropriate fire-extinguishing equipment is on hand. This includes using fire watch personnel. A fire watch has the dedicated responsibility to be stationed in the immediate area where hot work is being performed.  This job assignment is not designed to be a collateral function (where another work activity can be performed at the same time as being assigned as a fire watch).  Being a fire watch requires formal training and persons assigned to this position need to have immediate access to the appropriate fire extinguisher (such as a type ABC fire extinguisher that is designed to extinguish fires associated with combustibles, flammables and electrical components) and even a Class D (when combustible metals are involved). The fire watch person needs to be proficient with operating the fire extinguisher and understands emergency procedures. In addition, fire watch persons need to remain in the area where hot work is performed for at least 30 minutes after hot work has ceased. This is to ensure that ambers or sparks do not smolder leading to a potential reignition. In such a scenario, the fire watch’s immediate action would be to douse the area with water or, if more appropriate, use the designated fire extinguisher.     

Hot Work Permits have become an important component of performing hot work. A hot work permit is required for any temporary operation involving open flames or producing heat and/or sparks. In its simplest term, a hot work permit is really nothing more than a formal checklist to ensure that potential safety issues are addressed in the area you will be doing the work and that someone else (i.e. supervisor) agrees it is safe to do the work.  Therefore, the hot work permit helps us to ensure that the area is safe.  After the hot work is completed, the permit should then be filed in a project folder or other secured location (while OSHA does not specify any minimum records retention period, a general industry-accepted practice is one year). 

There are cases where a general hot work permit is used. This occurs when a specific location has been established as a permanent location to perform hot work activities.  In these cases, a “standing” permit can be issued and can remain in effect for up to one year. Changing conditions in the immediate area or nearby locations may require a revision or even a new permit. 

Typical tasks that need to be conducted in areas where hot work is being performed include:

• Maintaining clean floors (i.e. sweeping, vacuuming, etc.)
• Removal of flammable liquids, dust, lint, and oily deposits.
• Ducts and conveyor systems need to be protected or shut down to prevent sparks from being carried to other combustibles.
• Removing combustibles where possible; otherwise, the area will be protected with fire resistive tarpaulins or metal shields.
• Portable fire extinguisher, suitable for the type of possible fire, need to be readily available within the work area.

Depending on the specific type of hot work, personal protective equipment needs to be considered. Operations such as welding and torch cutting require specific eye and face protection. This includes specific lens shading which is presented in 29 CFR 1910.133 (General Industry) and 29 CFR 1926.102 (Construction). For example, when performing metal arc welding, the operator should have an eye shading of 10 -12; depending on the arc current used.  In addition, to protect persons in the area who may inadvertently look in the direction of hot work, welding curtains need to be installed (to prevent cornea damage from the produced UV radiation). Other PPE would include leather clothing (to protect operators from sparks), leather gloves and safety shoes.  

Industrial Hygiene monitoring and sampling can be very important as these methods can verify personal exposures to welding fumes as well as assessing flammable atmospheres that exceed 10% of the lower explosive limit and determining oxygen depletion (less than 19.5%). Such conditions require a stop work as they represent imminent danger, triggering potential life-threatening conditions.

The OSHA regulations, 29 CFR 1910, subpart Q, “Welding, Cutting, and Brazing,” and 29 CFR 1026, Subpart J, “Welding and Cutting,” provides a comprehensive description of S&H practices required for Hot Work.  Of course, when in doubt of the proper S&H requirements or you just need a little SME help, contact your S&H professional.

I cook with wine, sometimes I even add it to the food

W. C. Fields