54.01-5—Scope (modifies U-1 and U-2).

(a) This part contains requirements for pressure vessels. Table 54.01-5(a) gives a breakdown by parts in this subchapter of the regulations governing various types of pressure vessels, boilers, and thermal units.

(b) Pressure vessels are divided into Classes I, I-L (low temperature), II, II-L (low temperature), and III. Table 54.01-5(b) describes these classes and sets out additional requirements for welded pressure vessels.

(1) Class I-L and II-L pressure vessels must meet the applicable requirements in this part.

(2) Pressure vessels containing hazardous materials as defined in § 150.115 of this chapter must meet the requirements of this part or, as applicable, the requirements in 49 CFR parts 171-177 or part 64 of this chapter.

(3) Except as provided in paragraph (c)(4) of this section, Classes I, II, and III pressure vessels not containing hazardous materials must be designed and constructed in accordance with the requirements in Section VIII, division 1, of the ASME Boiler and Pressure Vessel Code (incorporated by reference; see 46 CFR 54.01-1) and must be stamped with the ASME “U” symbol. These pressure vessels must also comply with the requirements that are listed or prescribed in paragraphs (d) through (g) of this section. Compliance with other provisions in this part is not required.

(4) Classes II and III pressure vessels that have a net internal volume of less than 0.14 cubic meters (5 cubic feet) and do not contain hazardous materials must be stamped with either the ASME “U” or “UM” symbol. Compliance with other provisions in this part is not required.

(d) Pressure vessels described in paragraph (c)(3) of this section must—

(1) Have detailed plans that include the information required by § 54.01-18 (approved by the Office of Management and Budget under OMB control number 2130-0181);

(2) Meet § 54.01-35, § 54.20-3(c), and § 54.25-3 of this part ;

(3) Have pressure relief devices required by subpart ;

(4) Meet the applicable requirements in §§ 54.10-3, 54.10-20, and 54.10-25 for inspection, reports, and stamping;

(5) If welded, meet the post weld heat treatment and minimum joint and radiography requirement in Table 54.01-5(b); and

(6) If a steam generating pressure vessel, meet § 54.01-10.

(e) The plans required by paragraph (d)(1) of this section must be certified by a registered professional engineer to meet the design requirements in paragraph (d) of this section and in section VIII, division 1, of the ASME Boiler and Pressure Vessel Code. The certification must appear on all drawings and analyses. The plans must be made available to the Coast Guard prior to the inspection required by § 54.10-3(c).

(f) If a pressure vessel has more than one independent chamber and the chambers have different classifications, each chamber must, as a minimum, meet the requirements for its classification. If a single classification for the entire pressure vessel is preferred, the classification selected must be one that is required to meet all of the regulations applicable to the classification that is not selected. For example, if one chamber is Class I and one chamber is Class II-L, the only single classification that can be selected is Class I-L.

(g) The design pressure for each interface between two chambers in a multichambered pressure vessel must be—

(1) The maximum allowable working pressure (gauge) in the chamber with the higher pressure; or

(2) If one chamber is a vacuum chamber, the maximum allowable working pressure (absolute) in the other chamber minus the least operating pressure (absolute) in the vacuum chamber.

Table 54.01-5(a)—Regulation Reference for Boilers, Pressure Vessels, and Thermal Units

Service and pressure temperature boundaries	Part of subchapter regulating mechanical design	Part of subchapter regulating automatic control
Main (power) boiler: All	52	62
Pressure vessel: All	54	NA
Fired auxiliary boiler 1 (combustion products or electricity):
(a) Steam:
More than 103 kPa (15 psig)	52	2 62 or 63
Equal to or less than 103 kPa (15 psig)	53	63
(b) Hot water heating:
More than 689 kPa (100 psig) or 121 °C (250 °F)	52	63
Equal to or less than 689 kPa (100 psig) and 121 °C (250 °F)	53	63
(c) Hot water supply:
More than 689 kPa (100 psig) or 121 °C (250 °F)	52	63
Equal to or less than 689 kPa (100 psig) and 121 °C (250 °F)	53	63
Other:
(a) Fired thermal fluid heaters: All	52	63
(b) Unfired steam boiler:
More than 206 kPa (30 psig) or 454 °C (850 °F) 3	52	NA
Equal to or less than 206 kPa (30 psig) and 454 °C (850 °F)	54	NA
(c) Evaporators and heat exchangers: More than 103 kPa (15 psig) 4	54	NA
(d) Unfired hot water supply or heating boiler: More than 103 kPa (15 psig) 4	54	NA
1 Including exhaust gas types.
2 Boilers with heat input ratings >=12,500,000 Btu/hr. must have controls that meet part 62 . Boilers with heat input ratings <12,500,000 Btu/hr. must have controls that meet part 63 .
3 Temperature of working fluid.
4 Relief device is required even if designed for less than 103 kPa (15 psig).

Table 54.01-5(b)—Pressure Vessel Classification

Class	Service contents	Class limits onpressure andtemperature	Joint requirements 1,6,7	Radiography requirements, section VIII of the ASME Boiler and Pressure Vessel Code (incorporated by reference, see 46 CFR 54.01-1) 3,7	Post-weld heat treatment requirements 5,7
[Note to Table 54.01-5(b): All classes of pressure vessels are subject to shop inspection and plan approval.4]
I	(a) Vapor or gas(b) Liquid (c) Hazardous Materials 2	Vapor or gas: Over 600 p.s.i. or 700 °FLiquid: Over 600 p.s.i. or 400 °F	(1) For category A; (1) or (2) for category B. All categories C and D must have full penetration welds extending through the entire thickness of the vessel wall or nozzle wall	Full on all butt joints regardless of thickness. Exceptions listed in Table UCS-57 of section VIII of the ASME Boiler and Pressure Vessel Code do not apply	For carbon- or low-alloy steel, in accordance with Table UCS-56 of section VIII of the ASME Boiler and Pressure Vessel Code, regardless of thickness. For other materials, in accordance with section VIII.
I-L Low Temperature	(a) Vapor or gas, or liquid(b) Hazardous Materials 2	Over 250 p.s.i. and service temp. below 0 °F	(1) For categories A and B. All categories C and D must have full penetration welds extending through the entire thickness of the vessel wall or nozzle wall. No backing rings or strips left in place	Full on all butt joints regardless of thickness. Exceptions listed in Table UCS-57 of section VIII of the ASME Boiler and Pressure Vessel Code do not apply	For carbon- or low-alloy steel, in accordance with Table UCS-56 of section VIII of the ASME Boiler and Pressure Vessel Code, regardless of thickness. For other materials, in accordance with section VIII.
II	(a) Vapor or gas(b) Liquid (c) Hazardous Materials 2,3,6	Vapor or gas: 30 through 600 p.s.i. or 275 through 700 °FLiquid: 200 through 600 p.s.i. or 250 through 400 °F	(1) Or (2) for category A. (1), (2), or (3) for category BCategories C and D in accordance with UW-16 of section VIII of the ASME Boiler and Pressure Vessel Code	Spot, unless exempted by UW-11(c) of section VIII of the ASME Boiler and Pressure Vessel Code	In accordance with section VIII of the ASME Boiler and Pressure Vessel Code.
II-L Low Temperature	(a) Vapor or gas, or liquid(b) Hazardous Materials 2	0 through 250 p.s.i. and service temp. below 0 °F	(1) For category A; (1) or (2) for category B. All categories C and D must have full-penetration welds extending through the entire thickness of the vessel wall or nozzle wall	Spot. The exemption of UW-11(c) of section VIII of the ASME Boiler and Pressure Vessel Code does not apply	Same as for I-L except that mechanical stress relief may be substituted if allowed under Subpart 54.30 of this chapter.
III	(a) Vapor or gas(b) Liquid (c) Hazardous Materials 2,3,6	Vapor or gas: Under 30 p.s.i. and 0 through 275 °FLiquid: Under 200 p.s.i. and 0 through 250 °F	In accordance with Section VIII of the ASME Boiler and Pressure Vessel Code	Spot, unless exempted by UW-11(c) of section VIII of the ASME Boiler and Pressure Vessel Code	In accordance with section VIII of the ASME Boiler and Pressure Vessel Code.
1 Welded joint categories are defined under UW-3 of section VIII of the ASME Boiler and Pressure Vessel Code. Joint types are described in Table UW-12 of section VIII of the ASME Boiler and Pressure Vessel Code, and numbered (1), (2), etc.
2 See 46 CFR 54.20-2 .
3 See 46 CFR 54.25-8(c) and 54.25-10(d) .
4 See 46 CFR 54.01-15 and 54.10-3 for exemptions.
5 Specific requirements modifying Table UCS-56 of section VIII of the ASME Boiler and Pressure Vessel Code appear in 46 CFR 54.25-7 .
6 See 46 CFR 54.20-3(c) and (f) .
7 Applies only to welded pressure vessels.

(Approved by the Office of Management and Budget under OMB control number 2130-0181)

[CGFR 68-82, 33 FR 18828, Dec. 18, 1968, as amended by CGFR 69-127, 35 FR 9976, June 17, 1970; CGD 77-147, 47 FR 21809, May 20, 1982; 55 FR 696, Jan. 8, 1990; CGD 88-057, 55 FR 24236, June 15, 1990; CGD 85-061, 55 FR 41917, Oct. 16, 1990; CGD 95-027, 61 FR 26000, May 23, 1996; USCG-2000-7790, 65 FR 58460, Sept. 29, 2000; USCG-2003-16630, 73 FR 65165, Oct. 31, 2008]