The U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA) has been made aware of concerns regarding newly adopted requirements in Section 180.209(e) of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Prior to a January 21, 2016 Final Rule [Docket No. PHMSA-2013-0042 (HM-233F)], the requalification period corresponding to volumetric expansion testing for certain DOT cylinders was 12 years after the initial volumetric expansion testing conducted at the time of manufacture, and 12 years thereafter. The Final Rule, in part, reduced the requalification period from 12 years to 10 years, with a delayed compliance date of January 23, 2017. On January 13, 2017, the National Propane Gas Association (NPGA) submitted a Petition For Rulemaking & Emergency Stay [of] Cylinder Requalification Requirements requesting that PHMSA initiate a rulemaking to replace the requalification requirements established in HM-233F with the former requirements in 49 C.F.R. § 180.209(e). PHMSA hereby gives notice that while it reviews the NPGA Petition for Rulemaking, it will not take enforcement action against a person who requalifies DOT cylinders using volumetric expansion testing pursuant to a 12-year requalification period, as previously authorized by § 180.209( e) in effect on January 22, 2017. We will allow the use of either a 12 or 10-year requalification period for volumetric expansion testing until this notice is rescinded or otherwise modified. This notice is limited to the requirements recently adopted in 49 C.F .R. § 180.209( e ). This notice does not affect any other obligations that offerors or carriers may have under the HMR or any other applicable law. Issued March 17, 2017, in Washington, D.C. Acting Deputy Administrator Pipeline & Hazardous Materials Safety Administration.