# Thunderbird Cylinder — Hazardous Materials Safety Interpretation - **operation:** document - **citation:** 10-0077 - **title:** Thunderbird Cylinder — Hazardous Materials Safety Interpretation - **source type:** guidance - **agency:** Pipeline and Hazardous Materials Safety Administration - **status:** guidance - **official:** true - **published on:** 2011-09-14 - **effective on:** Not available - **summary:** 10-0077 response to Thunderbird Cylinder concerning 173.301, 180.209. - **machine formats:** - **json:** https://regulus.evalyn.ai/document/phmsa-interpretation-10-0077.json - **markdown:** https://regulus.evalyn.ai/document/phmsa-interpretation-10-0077.md - **app url:** https://regulus.evalyn.ai/document/phmsa-interpretation-10-0077 - **source url:** https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretations/2010/100077.pdf **body:** <<>> 1200 New Jersey Avenue SE U.S. Department Washington. DC 20590 of Transportation Pipeline and Hazardous Materials Safety Administration SFP 14 2011 Mr. Fred A. Nachman President Thunderbird Cylinder 4209 E. University Drive Phoenix, AZ 85034-7315 Ref. No.: 10-0077 . Dear Mr. Nachman: This responds to your letter requesting clarification ofthe requirements concerning the tare weight of liquefied petroleum gas (LPG) cylinders under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Q1. Does a low pressure (LPG) cylinder being visually inspected need to have its valve/PRD removed to verifY there is no liquid inside it that would result in improper tare weight verification? A1. No. A cylinder confonning to §180.209 used exclusively in LPG service may be given an external visual inspection in lieu ofa hydrostatic test. No measurement of the tare weight is required for the external visual inspection. When the cylinder exhibits corrosion, the cylinder must be further examined for condemnation. The cylinder must be examined by measuring tare weight in accordance with CGA C-6, 5.2.1.1 (1). The cylinder must be empty. The tare weight is measured with the valve! PRD connected. Cylinders exempt from tare weight measurement must be examined by measuring wall thickness in accordance with CGA C-6, 5.2.1.1 (2), (3), or (4). Q2. At the time ofrequalification, should the pressure relief device (PRD) be changed? A2. No. There is no regulatory requirement to change the PRD at the time of requalification. Pressure relief devices must be tested for leaks before a filled cylinder is shipped in accordance with §173.301(a)(2) and (3). Q3. Should it even be an option to hydrostatically test or steam clean LPG cylinders when ethyl mercaptan exposed to water/moisture is corrosive? <<>> A3. Cylinders containing LPG in accordance with § 180.209(g) may be given an external visual inspection in lieu of a hydrostatic pressure test. This would avoid adding moisture to the cylinder. If steam cleaning is used, it is the responsibility ofthe filler to make sure the cylinder is dry before filling with a hazardous material, if moisture is dangerous to the cylinder (§173.301(d». I hope this information is helpful. Ifwe can be of further assistance, please contact us. Sincerely, ~S;~ Ben Supko Chief, Standards Development Branch Standards and Rulemaking Division <<>> Date: April 1 , 2010 To: Hattie.mitchell@dot.gov Mark. toughity@dot.gov Ryan.posten@dot.gov Subj: Request for clarification concerning tare weights of propane/LPG cylinders Question No.1. Does a low pressure propane (LPG) cylinder being visually inspected need to have its valve/PRD removed to verify there is no liquid inside it that would result in improper tare weight verification? 0 Yes 0 No ' Reference is made to 49CFR180.209(g) Visual inspections A cylinder (DOT 3A, 3AA, 3B, 4B, 4BA, 4BW rylinders in liquefiedpetroleum gas) ... used exclusively in the service indicated may, instead of a periodic hydrostatic test, be given a complete exterior visual inspection ... in accordance with CGA Pamphlet C-6 ... CGA C-6-2007-5 Low pressure cylinders exempt from hydrostatic testin~-5.2.1.1 Corro~ c..~ limits When a cylinder exhibits corrosion, the cylinder shall be condemned when the tare weight is less than 90% of the original stamped tare weight. .. When determining tare weight, be sure the cylinder is emp!Jl. Cylinders that are used exclusively in noncorrosive gas service and meet one or more of the conditions below are exempt from tare weight checking requirement: ... Why would propane cylinders be exempted from tare weight verification when (1) that cylinder coming in for requalification after 12 years in its original service cycle and exposed to the elements will undoubtedly exhibit some amount of external corrosion, (2) the original stamped mfr tare weights were not necessarily correct, (3) the valve/PRD may have been changed out with one(s) of different weights, (4) it is unclear how much liquid remains in the cylinder effecting the weight, or (5) the cylinder contains the proper length dip tube on its spitter? Question No.2. At time ofrequalification, should the PRO be changed? 0 Yes 0 No It is our understanding that these resettable PRD's will reset at lower and lower PSI's as they continue to relieve pressures and reset over years in service. Question No.3. Should it even be an option to hydrostatically test or steam clean LPG cylinders when ethyl mercapin exposed to water/moisture is corrosive? 0 Yes 0 No ~llY submitted, ·~O~O(~ Fred A. Nachman President (Propane_ VisuaUnspection_C1arification_ 411O.doc) 4209 E. University Drive· Phoenix, AZ • 85034-7315 PHONE: 602.437.4600 • FAX: 602.437.5052 • EMAIL: fredn@cylinder.com - **truncated:** false - **body characters:** 4784