# External design pressure.

**Citation:** 49 CFR 178.270-10  
**Type / status:** regulation / historical  
**Agency:** Pipeline and Hazardous Materials Safety Administration  
**Effective:** 2005-10-01  
**Published:** Not stated

(a) Each portable tank not fitted with vacuum relief devices must be designed to withstand a positive external pressure differential of at least 0.4 bar (6 psig).

(b) Each portable tank fitted with vacuum relief devices must be designed to withstand a positive external pressure differential not les

## Document text

(a) Each portable tank not fitted with vacuum relief devices must be designed to withstand a positive external pressure differential of at least 0.4 bar (6 psig).

(b) Each portable tank fitted with vacuum relief devices must be designed to withstand a positive external pressure differential not less than the set pressure of the vacuum relief device and in any case at least 0.21 bar (3 psig).

[Amdt. 178-65, 46 FR 9896, Jan. 29, 1981, as amended at 66 FR 45387, Aug. 28, 2001]

## Provenance

- Official: Yes
- Source: <https://www.govinfo.gov/app/details/CFR-2005-title49-vol2/CFR-2005-title49-vol2-sec178-270-10>
- Source ID: `govinfo-cfr`
- SHA-256: `84bdcfe871fa6ac0f2a8ecd04a05eab3a8a468a9c4303e3c90b5da8b67b94b17`
- Retrieved: 2026-08-13T06:37:34.028Z
- Exported: 2026-08-25T00:59:53.513Z
- Document slug: `49-cfr-178-270-10`

### Source metadata

```json
{
  "part": "178",
  "section": "178.270-10",
  "subpart": "Subpart H—Specifications for Portable Tanks",
  "annualEdition": 2005,
  "revisedAsOf": "2005-10-01",
  "govInfoPackage": "CFR-2005-title49-vol2",
  "legalStatus": "official-annual-cfr-edition",
  "effectiveDateNote": null,
  "historicalAnchor": true,
  "historicalAnchorNote": "The section appears in an official annual CFR edition but is absent from the connected current eCFR corpus.",
  "jurisdiction": "US"
}
```