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d) HAZCAT IV. Negligible failure, which would not
likely expose operator/test personnel to any significant hazards.
Testing operations may continue without management action.
Note the above hazard categories do not contain a probability
of mishap occurrence. These categories suggest a probability of
end result associated with the hazard severity. HAZCAT I and
HAZCAT II categories are acceptable only when the probability of
mishap has been mitigated by design, testing, procedures, and
inspection to improbable, as defined by MIL-STD-882.
HAZCAT Guidelines. Generally, most components within a
specific system are all the same HAZCAT. Since HAZCAT I
designation means a malfunction endangers the lives of
operator/test personnel and no failure action is possible,
stricter material selection and control; fabrication and
installation procedures; and quality control testing is required
on these items.
Likewise, HAZCAT II items have more stringent requirements than
HAZCAT III and HAZCAT IV items. Additionally it is recognized
that failure of a HAZCAT II item, such as a pressurized gage
isolation valve, could result in operator death or severe injury.
However, the probability that the severity would be as great as
that encountered during failure of a HAZCAT I item (such as a
pressure vessel) is considered improbable. Therefore, when
determining HAZCAT boundaries, engineering judgment on a case
basis, as well as consultation with the SCA, may be required.
The following guidelines are provided to assist in the
determination of HAZCAT designations:
a) HAZCAT I items include the pressure boundary to
which the operator/test personnel are exposed and the first
pressure piping isolation valves connected to the pressure
boundary. HAZCAT I items, dependent on design of the facility,
may also include other system piping and components. For example,
if hazardous gases or fluids exist, then all piping and
components containing them would be HAZCAT I. Items include:
Pressure vessel and hatches
Pressure vessel view ports
Pressure vessel penetrator fittings
b) HAZCAT II items include systems, equipment, and
components which have sufficient isolation boundaries that injury
can be precluded by securing the source of pressure, gas flow,