51122 Federal Register / Vol. 71, No. 167 / Tuesday, August 29, 2006 / Rules and Regulations DEPARTMENT OF TRANSPORTATION of SLC are not yet fully understood, it and use of DOT specification cylinders. appears the cracks primarily originate On May 8, 2003, we issued a subsequent Pipeline and Hazardous Materials from the bottom of the neck of the final rule (68 FR 24653) making further Safety Administration cylinder, at or below the lowest thread revisions in response to appeals. In position in the interior of the cylinder. these final rules, we added the 49 CFR Parts 173 and 180 The cracking was first brought to following amendments pertaining to [Docket No. PHMSA–03–14405 (HM–220F)] PHMSA’s attention by persons retesting DOT specification cylinders made with cylinders under the periodic retest aluminum alloy 6351–T6: RIN 2137–AD78 procedures of § 180.209 of the • Removed the authorization for the Hazardous Materials Regulations (HMR; manufacture of DOT specification Hazardous Materials: Aluminum 49 CFR parts 171–180). The majority of cylinders made with aluminum alloy Cylinders Manufactured of Aluminum SLC-related ruptures have occurred in 6351–T6 because cylinders Alloy 6351–T6 Used in SCUBA, SCBA, self-contained underwater breathing manufactured with this aluminum alloy and Oxygen Services—Revised apparatus (SCUBA), self-contained have a greater risk of failure than other Requalification and Use Criteria breathing apparatus (SCBA), and oxygen aluminum cylinders. • AGENCY: Pipeline and Hazardous services. Since 1994, the Pipeline and Prohibited the use of cylinders Materials Safety Administration Hazardous Materials Safety made with aluminum alloy 6351–T6 for (PHMSA), DOT. Administration (PHMSA, we) has been the transportation of materials notified of thirteen suspected SLC poisonous by inhalation in Hazard Zone ACTION: Final rule. ruptures of cylinders manufactured of A effective on October 1, 2002. After SUMMARY: This final rule revises the aluminum alloy 6351–T6. Five of the that date, cylinders made of aluminum Hazardous Materials Regulations to thirteen ruptures resulted in serious alloy 6351–T6 may not be filled and address a known safety problem with injuries. Data from manufacturers show offered for transportation in toxic cylinders manufactured of aluminum there are thousands of cylinders with inhalation hazard service. • alloy 6351–T6. The revisions include an small, non-leaking cracks, which are Prohibited the use of cylinders inspection and testing program for early regularly detected during a diligent, manufactured of aluminum alloy 6351– detection of sustained load cracking on detailed requalification process. T6 for gases having pyrophoric Manufacturers of cylinders made from properties. cylinders manufactured of aluminum • alloy 6351–T6 and used in self- the 6351–T6 aluminum alloy have Required a visual inspection of contained underwater breathing conducted research, testing, and DOT specification or exemption apparatus (SCUBA), self-contained analysis to determine whether there is cylinders made of aluminum alloy breathing apparatus (SCBA), and oxygen any correlation between SLC and the 6351–T6 for evidence of SLC in the neck services. probability of a cylinder rupture. The and shoulder area. data indicate the cylinders may leak but On September 10, 2003, the Research DATES: Effective date: January 1, 2007. not rupture when operated at marked and Special Programs Administration, FOR FURTHER INFORMATION CONTACT: service pressure. The data also indicate the predecessor agency to PHMSA, Mark Toughiry, Office of Hazardous the probability of cracking increases published an NPRM (68 FR 53314) Materials Technology, (202) 366–4545, with an increase in stress levels. proposing to amend HMR requirements or Kurt C. Eichenlaub, Office of We performed additional applicable to aluminum cylinders Hazardous Materials Standards, (202) metallurgical analysis on several manufactured using aluminum alloy 366–8553; PHMSA, U.S. Department of ruptured cylinders to verify the cause of 6351–T6. In the NPRM, for cylinders Transportation, 400 Seventh Street, failure and failure mode. (See the manufactured of aluminum alloy 6351– SW., Washington, DC 20590–0001. metallurgical analysis reports at http:// T6 used in SCUBA, SCBA, and oxygen SUPPLEMENTARY INFORMATION: hazmat.dot.gov/pubs/reports/cylinder/ service, we proposed the following _ _ Contents 3al cyls info.htm). Those metallurgical amendments: analyses revealed SLC caused the • A combined visual and eddy I. Background cylinder ruptures, but the results were current examination at the time of II. Analysis of Comments to SNPRM inconclusive as to why the cylinders requalification. III. Section-by-Section Review • IV. Regulatory Analyses and Notices abruptly ruptured instead of developing A new Appendix C to Part 180, to A. Statutory/Legal Authority for This leaks. North American manufacturers specify the procedure to conduct the Rulemaking discontinued using aluminum alloy eddy current examination. B. Executive Order 12866 and DOT 6351–T6 prior to 1990, replacing it with • Suitable safeguards to protect Regulatory Polices and Procedures aluminum alloy 6061–T6, which is not personnel and facilities should a C. Executive Order 13132 susceptible to SLC. Cylinders cylinder fail during the filling process. D. Executive Order 13175 manufactured of aluminum alloy 6351– Although we believe the thirteen E. Regulatory Flexibility Act, Executive T6 prior to 1990 include seamless reported SLC ruptures under represent Order 13272, and DOT Procedures and aluminum cylinders marked ‘‘DOT the extent of the SLC issue, we did not Policies 3AL;’’ and those marked with one of the have sufficient data to determine F. Paperwork Reduction Act whether the SLC-related ruptures G. Regulation Identifier Number (RIN) following exemption or special permit H. Unfunded Mandates Reform Act numbers: 6498, 7042, 8107, 8364, and extend beyond those services discussed I. Environmental Assessment 8422. We estimate approximately 3.7 above. Therefore, in the NPRM we J. Privacy Act million U.S. cylinders manufactured requested additional information from from aluminum alloy 6351–T6 are manufacturers and users who were I. Background currently in use in SCUBA, SCBA, and aware of a cylinder rupture, whether Cylinders made of aluminum alloy oxygen services. domestic or foreign, involving a DOT 6351–T6 are known to be susceptible to On August 8, 2002, we published a 3AL cylinder or any other cylinder sustained load cracking (SLC) in the final rule (67 FR 51626) amending the manufactured from aluminum alloy neck and shoulder area of the cylinder. requirements of the HMR applicable to 6351–T6. More broadly, we invited While the exact cause and mechanism the maintenance, requalification, repair, commenters to address the issue of VerDate Aug<31>2005 14:37 Aug 28, 2006 Jkt 208001 PO 00000 Frm 00028 Fmt 4700 Sfmt 4700 E:\FR\FM\29AUR1.SGM 29AUR1 cprice-sewell on PROD1PC66 with RULES Federal Register / Vol. 71, No. 167 / Tuesday, August 29, 2006 / Rules and Regulations 51123 whether the new inspection 14405–28); and, Amy Morgan Bruecks firefighter, substantially increasing the requirements proposed in the NPRM (Bruecks; RSPA–2003–14405–29). These risk of injury or fatality in the event of should apply to cylinders manufactured comments are available in their entirety a cylinder rupture. To date, there have of aluminum alloy 6351–T6 and used in at the U.S. DOT Docket Management been no reported ruptures involving services other than SCUBA, SCBA, or System Web site: http://dms.dot.gov, DOT 3AL cylinders manufactured of oxygen. under Docket No. PHMSA–03–14405. aluminum alloy 6351–T6 and used in On October 26, 2005, based on In this final rule, we summarize carbon dioxide, fire extinguisher, or comments received in response to the comments submitted to the docket, other industrial gas service. Therefore, NPRM, we published an SNPRM (70 FR address concerns raised by commenters, we are not expanding the scope of the 61762) to revise the amendments and discuss our decisions on specific rule to include all DOT 3AL cylinders originally proposed in the NPRM, issues. manufactured of aluminum alloy 6351– expand the scope of the rulemaking, and A. Carbon Dioxide Service T6. propose additional requirements for Two commenters [CGA; Barlen] to the DOT 3AL cylinders manufactured of The SNPRM proposed enhanced SNPRM oppose expanding the scope of aluminum alloy 6351–T6. In the requalification requirements and a 40- the rule to include cylinders used in SNPRM, we proposed to: year service life for DOT 3AL cylinders carbon dioxide service. One commenter • Require a combined visual and manufactured of aluminum alloy 6351– [CGA] states, ‘‘SLC is most likely to eddy current examination at the time of T6 and used in SCUBA, SCBA, oxygen, occur at high pressures. Because requalification of DOT 3AL cylinders and carbon dioxide services. DOT 3AL cylinders used in [carbon dioxide] manufactured of aluminum alloy 6351– cylinders used for carbon dioxide service are operated at a lower pressure T6 and used in carbon dioxide service, service were not included in the original than those used in SCBA and SCUBA in addition to those used in SCUBA, NPRM, but were added to the SNPRM service, the rate of cracking for cylinders SCBA, and oxygen services. as a result of our own initiative and in in [carbon dioxide] service will be • Impose a 40-year service life for response to comments submitted to the substantially less than for those used in cylinders manufactured of