The Pipeline and Hazardous Materials Safety Administration is taking public comment on a petition that would let Gexcon U.S., Inc. use its EFFECTS v12.2.0 software to calculate the safety buffers required around liquefied natural gas facilities.
What Gexcon is asking for
Gexcon filed the petition on December 11, 2023, asking PHMSA to approve EFFECTS v12.2 as an alternate model under 49 CFR 190.9. The agency's LNG siting rules, in 49 CFR part 193, require operators to size a flammable vapor-gas dispersion exclusion zone around each LNG container and transfer system. That zone is the area around a facility where an operator or a government agency controls all activity, meant to keep the public away from flammable vapor and from direct exposure to a flame if a release or ignition happens.
How the review works
Under 49 CFR 193.2059(a), operators currently must calculate that zone using either the DEGADIS 2.1 Dense Gas Dispersion model or the FEM3A model. The rule lets PHMSA's Administrator approve a different model if it accounts for the same physical factors as DEGADIS 2.1 and FEM3A and has been checked against experimental test data.
PHMSA published a draft letter of decision on Gexcon's petition along with the notice. Both are posted in Docket No. PHMSA-2024-0164. The agency will weigh comments filed by October 9, 2026 before it issues a final decision.
