46 CFR § 56.04-2 - Piping classification according to service.

---
identifier: "/us/cfr/t46/s56.04-2"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "46 CFR § 56.04-2 - Piping classification according to service."
title_number: 46
title_name: "Shipping"
section_number: "56.04-2"
section_name: "Piping classification according to service."
chapter_name: "COAST GUARD, DEPARTMENT OF HOMELAND SECURITY"
subchapter_number: "F"
subchapter_name: "MARINE ENGINEERING"
part_number: "56"
part_name: "PIPING SYSTEMS AND APPURTENANCES"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "33 U.S.C. 1321(j), 1509; 43 U.S.C. 1333; 46 U.S.C. 3306, 3703; E.O. 12234, 45 FR 58801, 3 CFR, 1980 Comp., p. 277; E.O. 12777, 56 FR 54757, 3 CFR, 1991 Comp., p. 351; DHS Delegation No. 00170.1, Revision No. 01.4."
regulatory_source: "CGFR 68-82, 33 FR 18843, Dec. 18, 1968, unless otherwise noted."
cfr_part: "56"
---


# 56.04-2 Piping classification according to service.

The designation of classes according to service is found in table 1 to § 56.04-2.

Table 1 to § 56.04-2—Pressure Piping Classification

| Service | Class | Pressure (p.s.i.g.) |  | Temp. (°F) |
| --- | --- | --- | --- | --- |
| Class B and C poisons | I | any | and | 0 and above. |
|  | I-L | any | and | below 0. |
|  | II | ( ) | ( ) | ( ) |
|  | II-L | ( ) | ( ) | ( ) |
| Gases and vapors | I | above 150 | or | above 650. |
|  | I-L | above 150 | and | below 0. |
|  | II | 150 and below | and | 0 to 650. |
|  | II-L | 150 and below | and | below 0. |
| Liquefied flammable gases | I | above 150 | and | 0 and above. |
|  | I-L | above 150 | and | below 0. |
|  | II | 150 and below | and | 0 and above. |
|  | II-L | 150 and below | and | below 0. |
| Molten sulphur | I | above 225 | or | above 330. |
|  | II | 225 and below | and | 330 and below. |
| Cargo liquids Grades A through D | I | above 225 | or | above 150. |
|  | I-L | above 225 | and | below 0. |
|  | II | 225 and below | and | 0 to 150. |
|  | II-L | 225 and below | and | below 0. |
| Cargo liquids Grade E | I | above 225 | or | above 400. |
|  | I-L | above 225 | and | below 0. |
|  | II | 225 and below | and | 0 to 400. |
|  | II-L | 225 and below | and | below 0. |
| Water | I | above 225 | or | above 350. |
|  | II | 225 and below | and | 350 and below. |
| Fuels (Bunker, diesel, gasoline, etc.) | I | above 150 | or | above 150. |
|  | II | 150 and below | and | 150 and below. |
| Lubricating oil | I | above 225 | or | above 400. |
|  | II | 225 and below | and | 400 and below. |
| Asphalt | I | above 225 | or | above 400. |
|  | II | 225 and below | and | 400 and below. |
| Heat transfer oil | I | above 225 | or | above 400. |
|  | II | 225 and below | and | 400 and below. |
| Hydraulic fluid | I | above 225 | or | above 400. |
|  | II | 225 and below | and | 400 and below. |

|  |  |
| --- | --- |
| Flammable or combustible dangerous cargoes. | Refer to specific requirements of part 40 of this chapter. |
| Other dangerous cargoes. | Refer to specific requirements of part 98 of this chapter. |
| Where doubt exists as to proper classification, refer to the Commandant for resolution. |  |
| For definitions, see parts 30, 151, and 154 of this chapter. Note that the category “B and C” poisons is not used in the rules applying to self-propelled vessels (part 153 of this chapter). |  |
| Not permitted except inside cargo tanks approved for Class B and C poisons. |  |

[CGFR 68-82, 33 FR 18843, Dec. 18, 1968, as amended by CGD 73-254, 40 FR 40164, Sept. 2, 1975; CGD 73-96, 42 FR 49024, Sept. 26, 1977; USCG-2020-0634, 89 FR 50131, June 12, 2024]