NFPA Journal - May/June 2017 - 45

tank collapsed, and one of the contract workers was killed;
eight others were injured, and a significant volume of sulfuric acid was released to the environment.
The CSB began systematically tracking hot work incidents
following the July 29, 2008, accident at the Packaging Corporation of America (PCA) in Tomahawk, Wisconsin. Workers
were performing welding work above an 80-foot-tall storage
tank that contained highly flammable hydrogen gas, the
product of bacterial decomposition of organic fiber waste-a
mixture of recycled paper pulp and water-inside the tank.
This was a new hazard, identified by the CSB. Hot work
ignited flammable vapors, resulting in an explosion that
killed three workers and injured another.

In the 10 months following the explosion at PCA, the
CSB investigated five additional incidents where hot work
ignited flammable gas or vapor, including an explosion at
MAR Oil in La Rue, Ohio, that killed two contractors in
October 2008; an explosion that killed one and injured
another at EMC Used Oil in Miami, Florida, in December
2008; an explosion that killed a contract welder at ConAgra
Foods in Boardman, Oregon, in February 2009; an explosion
at A.V. Thomas Produce in Atwater, California, in March
2009 that severely burned two employees; and the explosion
of a massive gasoline storage tank that killed three workers
at a TEPPCO Partners fuel distribution facility in Garner,
Arkansas, in May 2009.

5 Hot Work Misconceptions

by Guy Colonna

SAFETY TRAININGS SHED LIGHT ON COMMON INACCURACIES SURROUNDING THE PRACTICE

espite repeated fires started by hot work and an NFPA standard on safe hot work practices-NFPA 51B, Fire Prevention
During Welding, Cutting, and Other Hot Work, which was first
issued in 1962-hot work-related blasts and blazes continue to
occur. According to the NFPA report "Structure Fires Started by
Hot Work," issued last September, fire departments in the United
States responded to an average of 4,400 structure fires a year
involving hot work from 2010 to 2014.
In March 2014, two Boston firefighters died responding to a fire
that was started by hot work. As a result of that tragedy, NFPA has
been working with the city and its fire department since September to deliver hot work safety training to construction workers in
the Boston area. So far, over 13,000 workers have participated in
the NFPA-designed program. I have led over 40 of these trainings,
and in my experience, these are some of the major misconceptions surrounding hot work.
THE MISCONCEPTION: Hot work is just welding and torch cutting.
The truth: As defined by NFPA 51B, hot work is any work that
involves "burning, welding, or a similar operation that is capable of
initiating fires or explosions." It's not just work that involves flames.
After all, you don't need a flame to generate heat. Activities such as
drilling, soldering, brazing, tapping, grinding, heat treating, chipping,
thawing pipes, and abrasive blasting-often referred to as sand
blasting-are all considered hot work.
THE MISCONCEPTION: Soldering, which is often involved in
plumbing-related tasks, is not a big problem.
The truth: According to the NFPA report on hot work structure
fires, soldering causes 34 percent of hot work fires started in
homes. (We don't have the data on whether the work is performed
by contractors or homeowners engaged in DIY repairs.) Nevertheless, because this work must usually be performed close to
combustible construction materials and insulation, it can be a
significant hot work safety challenge.
THE MISCONCEPTION: The hazard goes away once the hot work
operation ceases.
The truth: NFPA 51B and other hot work safety practices require
someone-normally a trained fire watch-to remain at the work

site for a minimum of 30 minutes after hot work has stopped
to monitor the site for any smoldering conditions or reignition
from hot embers or retained heat. And heat has a way of sticking
around. Insurance data indicates that retained heat has contributed
to reignition conditions up to four hours after the hot work was
performed.
THE MISCONCEPTION: Hot work safety is the responsibility of
the person in charge.
The truth: NFPA 51B requires establishing a hot work safety team
consisting of three individuals: the person in charge (referred to
in NFPA 51B as the permit authorizing individual, or PAI); a hot
work operator; and a fire watch. The standard defines their duties
as being responsible for safety on the work site and identifying
any change in conditions so that hot work stops until the conditions are reevaluated. This is a particular point of emphasis in the
training we are conducting for Boston. Essentially, our message on
the job site for all workers is if they see something that might be
an unsafe change in condition, they need to tell someone so it can
be checked.
THE MISCONCEPTION: Hot work residue, including sparks, slag,
spatter, and heat transfer, are usually only transmitted a limited
distance.
The truth: Many types of hot work, such as welding, grinding,
and torch cutting, produce sparks, slag, or spatter that can reach
well beyond the immediate work area. For that reason, NFPA 51B
establishes a minimum safe distance of 35 feet in all directions
from the location of the hot work. In other words, combustible
materials must be moved at least 35 feet away from the work
to prevent contact with the hot work residue, such as sparks or
slag. That distance is only a minimum, and conditions such as
wind or proximity to dry grass might necessitate a greater distance. While working at an elevated location, for instance, where
sparks can fall vertically, I have seen hot work residue travel
distances in excess of 100 feet.
GUY COLONNA is NFPA division director of technical services.
NFPA members and AHJs can use the Technical Questions tab to
post queries on NFPA 51B at nfpa.org/51b.

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Table of Contents for the Digital Edition of NFPA Journal - May/June 2017