# -4 Insulation.

**Citation:** 49 CFR 179.200-4  
**Type / status:** regulation / current  
**Agency:** Pipeline and Hazardous Materials Safety Administration  
**Effective:** 2026-08-18  
**Published:** Not stated

(a) If insulation is applied, the tank shell and expansion dome when used must be insulated with an approved material. The entire insulation must be covered with a metal jacket of a thickness not less than 11 gauge (0.1196 inch) nominal (Manufacturer's Standard Gauge) and flashed around all openings

## Document text

(a) If insulation is applied, the tank shell and expansion dome when used must be insulated with an approved material. The entire insulation must be covered with a metal jacket of a thickness not less than 11 gauge (0.1196 inch) nominal (Manufacturer's Standard Gauge) and flashed around all openings so as to be weather tight. The exterior surface of a carbon steel tank and the inside surface of a carbon steel jacket must be given a protection coating.

(b) If insulation is a specification requirement, it shall be of sufficient thickness so that the thermal conductance at 60 °F is not more than 0.225 Btu per hour, per square foot, per degree F temperature differential, unless otherwise provided in § 179.201-1. If exterior heaters are attached to tank, the thickness of the insulation over each heater element may be reduced to one-half that required for the shell.

[29 FR 18995, Dec. 29, 1964. Redesignated at 32 FR 5606, Apr. 5, 1967, and amended by Amdt. 179-10, 36 FR 21349, Nov. 6, 1971; Amdt. 179-50, 60 FR 49078, Sept. 21, 1995]

## Provenance

- Official: Yes
- Source: <https://www.ecfr.gov/on/2026-08-18/title-49/section-179.200-4>
- Source ID: `ecfr`
- SHA-256: `3f39892735c191d1c23d1ed45a9d95eb78aa078220aaa6e28a4a4ebb19c9f044`
- Retrieved: 2026-08-20T05:46:20.606Z
- Exported: 2026-08-23T11:50:59.430Z
- Document slug: `49-cfr-179-200-4`

### Source metadata

```json
{
  "cfrTitle": 49,
  "part": "179",
  "section": "179.200-4",
  "subpart": "Subpart D—Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW, 115AW, and 117AW)",
  "corpusVersion": "2026-08-18",
  "jurisdiction": "US"
}
```