Criticality: High Progress: Not Addressed Score: 40 DOT Relevance: §192.5
Description of Key Area
Class location comprises
a portion of Subpart A (General) of 49 CFR 192. Class location refers to the
distance a structure must be located from the pipeline. A “class location unit”
is defined in 49 CFR 192 as “an on-shore area that extends 220 yards on either
side of the centerline of any continuous 1-mile length of pipeline.”
Discussion of Criticality
The parameters for class
location are based on natural gas considerations. The underlying definition of
class location must be redefined for hydrogen.
Discussion of Progress
The current plans of the
ASME B31.12 hydrogen task group call for using only the location class 3 and 4
to maintain a classification designation familiar to pipeline operators and
designers. This will increase the level of conservatism in the design of new
lines and require more frequent inspections in the integrity management
process. The ASME B31.12 hydrogen task group is also reviewing a new DOT
report, TTO13, entitled “Potential Impact Radius Formulae for Flammable Gasses
Other Than Natural Gas, June 2005”. If the task group agrees with the report
results, it will change the “potential impact area” equation for radius of
impact calculations and use this in conjunction with ASME B31.8S (equation 1 in
ASME B31.8S, section 3.2).
Recommendations
The ASME effort should
be monitored and its recommendations assessed for potential incorporation by reference
into the federal code.
