Proceedings magazine is a communication tool for the Coast Guard's Marine Safety & Security Council. Each quarterly magazine focuses on a specific theme of interest to the marine industry.
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50 Proceedings Fall 2015 www.uscg.mil/proceedings Chemical Transportation Advisory Committee Recommendations In 2013, the Coast Guard tasked Chemical Transportation Advisory Committee (CTAC) members to provide their recom- mendations on appropriate LNG barge design standards. To accomplish this, the Chemical Transportation Advisory Committee held seven public meetings, spanning two years, to collect information for their report. CTAC recommended that 46 CFR Part 154 — Safety Standards For Self-Propelled Vessels Carrying Bulk Liquefed Gases — be used as a basis to develop LNG barge standards. The CTAC recommendations are applicable only to barges on domestic routes, unmanned vessels, LNG transport in bulk, vessels dedicated to LNG carriage only, and those that do not supply power or fuel from a barge to towing vessel. In summary, the main areas of focus for the CTAC modifcations are: ● materials, ● cargo containment systems, ● electrical requirements, ● frefghting, ● gas detection, ● safety equipment. All LNG barges must meet requirements in 46 CFR Subchapter D — Tank Barges. The Chemical Transportation Advisory Committee also recommended applying modifed versions of 46 CFR 154 subparts C and E to LNG barges. CTAC's recommendations diferentiated between unrestricted and restricted, or ocean-going and inland barges, respectively. Modifcations to subchapter D and subpart C and E of 46 CFR 154 are summarized as: ● Barge hull structures should meet requirements in 46 CFR part 154 subpart C, except unrestricted barges may use American Bureau of Shipping (ABS) Rules for Building and Classing Steel Barges and inland barges may use the ABS Rules for Building and Classing Steel Vessels for Service on Rivers and Intracoastal Waterways. Where appropriate, operators should also use applicable portions regarding LNG from the ABS Rules for Building and Classing Steel Vessels. Equivalent rules from other recognized classifca- tion societies may be substituted for ABS rules. ● Barges in unrestricted service must meet the require- ments for stability and cargo tank location in 46 CFR 154 subpart C; however, restricted barges can use 46 CFR part 172 subpart E. ● Cargo containment systems of all barges are suggested to meet the requirements in 46 CFR part 154 subpart C. Inland barges may use the dynamic load calculations outlined in part §38.05-2, but unrestricted barges are required to meet the dynamic loads in section §154.409. The following recommended modifcations to 46 CFR 154 subchapter O apply to all barges, whether restricted or unre- stricted: ● Equipment using liquefed natural gas as fuel on the barge may meet the requirements in 46 CFR part 154.705- 709 or CG-521 Policy Letter 01-12 Equivalency Determina- tion — Design Criteria for Natural Gas Fuel Systems. ● The electrical system requirements have been signif- cantly modified to align with the international stan- dards for electrical equipment in hazardous spaces. In particular, hazardous zones have been redrafted. Current hazardous zones under 46 CFR 154 are either "gas safe" or "gas dangerous." The CTAC recommendations divide the hazardous zones into four categories: ○ Zone 0 is a hazardous location in which an explo- sive gas or vapor in mixture with air is continuously present or present for long periods. ○ Zone 1 is a hazardous location in which an explosive gas or vapor in mixture with air is likely to occur in normal operating conditions. ○ Zone 2 is a hazardous location in which an explosive gas or vapor in mixture with air is not likely to occur in normal operating conditions, or in which such a mixture, if it does occur, will only exist for a short time. ○ Nonhazardous spaces are gas-safe. ● Unlike subchapter D barges, for which no fxed frefghting is required, LNG barges should have basic frefghting capabilities, including water spray and dry chemical systems. ● Barges should meet the gas detection requirements of 46 CFR 154 subpart C, with some modifcations that require the capability to monitor and control cargo tanks and equipment on the barge from remote locations, such as the towing vessel or land-based facility. ● Additionally, barges' essential frst response gear should include personal protective and rescue equipment.