Chemical Engineering November 2013 - 37

Source: BLS
Roadway incidents
Homicides
Falls, slips, trips
Contact with objects
and equipment
Exposure to
harmful substances
or environments
Fires and explosions
2%
3%
5
10
15
20
25
Percent of fatal work injuries within gender
FIGURE 2. Statistics tell a similar story, regardless of gender. For those exposed to
harmful substances, there is only a 2% differential between men and women
that resulted in 8 deaths and 128 injuries;
the September 2005 explosion
at the Texas City, BP refinery where
15 were killed and 180 injured; and
the February 2010 explosion at the
Kleen Energy Power Plant in Middletown,
Conn. that killed 6 and injured
more than 50 personnel.
Not only do such incidents capture
the attention of the public and lawmakers
alike, they also capture the
attention of organizations such as
the NFPA (National Fire Protection
Association) and ASME. These and
other organizations will quite often
modify or introduce content into their
codes and standards in response to the
causal effects of such incidents.
While many relevant factors are required
for a safe operating facility, including
a well-thought-out preventive
maintenance program and operating
procedures, this article will concentrate
on piping.
LethaL ChemiCaLs DefineD
Information on chemical substances
comes from many sources. To put the
discussion of potentially lethal chemicals
into context, we can consider
such resources as the NFPA, OSHA
(29CFR), the U.S. Environmental
Protection Agency (EPA) (40CFR),
and REACH (Registration, Evaluation,
Authorization and Restriction of
Chemicals), a European Union Regulation,
as well as the U.S. Dept. of
Transportation (DOT; 49 CFR).
OSHA currently addresses 400
substances within their regulations
and the OSHA Chemical Sampling
Information database contains data
on approximately 1,500 chemical substances.
The EPA's TSCA (Toxic Substance
Control Act - currently under
legislative review in the U.S.) Chemical
Substance Inventory contains over
62,000 chemical substances. There are
currently more than 100,000 Material
Safety Data Sheets (MSDS) on
file. The present discussion is acutely
focused on the 140 chemicals found
in OSHA's " List of Highly Hazardous
Chemicals, Toxics, and Reactives
(Mandatory) " found within 29 CFR
1926.64 Appendix A.
Focusing even further, this article
considers only those chemicals that are
considered lethal from a toxic standpoint.
This set of chemicals meets the
criteria for ASME B31.3 Category M
Fluid Service.
The 2012 edition of the ASME
B31.3 Process Piping Code defines
Category M fluid service as: " a fluid
service in which the potential for
personnel exposure is judged to be
significant, and in which a single
exposure to a very small quantity of
a toxic fluid, caused by leakage, can
produce serious irreversible harm to
persons on breathing or bodily contact,
even when prompt restorative
measures are taken. "
The OSHA Hazard Communication
Standard, Subpart Z, Toxic and Hazardous
Substances 29 CFR 1910.1200,
defines hazardous chemicals as those
that present " a physical hazard or a
health hazard. " The standard goes on
to define physical hazard as " a chemical
for which there is scientifically
valid evidence that it is a combustible
liquid, a compressed gas, explosive,
flammable, an organic peroxide, an
oxidizer, pyrophoric, unstable (reactive)
or water-reactive. "
It also defines a health hazard as
30
35
6%
17%
5%
7%
Females = 383
Males = 4,045
29%
9%
21%
24%
16%
15%
" a chemical for which there is statistically
significant evidence based on
at least one study conducted in accordance
with established scientific
principles that acute or chronic health
effects may occur in exposed employees.
The term 'health hazard' includes
chemicals which are carcinogens, toxic
or highly toxic agents, reproductive
toxins, irritants, corrosives, sensitizers,
hepatotoxins, nephrotoxins, neurotoxins,
agents which act on the hematopoietic
system, and agents which
damage the lungs, skin, eyes, or mucous
membranes. "
When defining the term " toxic " in
Appendix A of 29 CFR 1910.1200,
OSHA separates the criteria according
to three forms of human exposure.
* Toxic by ingestion. A chemical that
has a median lethal dose (LD50)1 of
more than 50 milligrams per kilogram
(mg/kg) of body weight but not
more than 500 mg/kg of body weight
when administered orally to albino
rats weighing between 200 and 300
grams each.
* Toxic by contact. A chemical that
has a median lethal dose (LD50) of
more than 200 mg/kg but not more
than 1,000 mg/kg of body weight
when administered by continuous
contact for 24 h (or less if death occurs
within 24 h) with the bare skin
of albino rabbits weighing between
two and three kilograms each.
* Toxic by inhalation. A chemical
that has a median lethal concentration
(LC50) in air of more than
200 parts per million (ppm) but not
more than 2,000 ppm by volume of
gas or vapor, or more than 2 mg/L,
but not more than 20 mg/L of mist,
fume or dust, when administered by
continuous inhalation for one hour
(or less, if death occurs within 1 h)
to albino rats weighing between 200
and 300 grams each.
The same Appendix A also defines a
category of chemicals that are " highly
1. LD50, in which LD stands for " lethal dose, "
is the amount of a material, given all at once,
which causes the death of 50% of a group of test
animals. The LD50 is one way to measure the
short-term poisoning potential (acute toxicity) of
a material. LC50, in which LC stands for " lethal
concentration " is, in inhalation experiments, the
concentration of an airborne chemical that kills
50% of the test animals in a given time (usually
4 h). In environmental studies, LC values
can also mean the concentration of a chemical
in water.
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Chemical Engineering November 2013

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