{"data":{"id":"us/49-cfr-179.220-4","jurisdiction":"us","citation":"49 CFR 179.220-4","heading":"-4 Insulation.","body":"The annular space between the inner container and the outer shell must contain an approved insulation material.","path":["Title 49—Transportation","Subtitle B—Other Regulations Relating to Transportation","CHAPTER I—PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION","SUBCHAPTER C—HAZARDOUS MATERIALS REGULATIONS","PART 179—SPECIFICATIONS FOR TANK CARS","Subpart D—Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW, 115AW, and 117AW)"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-49.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:34Z","sha256":"4f1a4a99c58eca604719535324709f293abf998c7d4a0710c091096906b8fbd6","source_id":"us-cfr","stale":true,"prev":"us/49-cfr-179.220-3","next":"us/49-cfr-179.220-6"},"notice":"GroundRules: Original legal text. Not legal advice."}