#### § 54.25-10 Low temperature operation—ferritic steels (replaces UCS-65 through UCS-67).

(a) *Scope.*

(1) This section contains requirements for pressure vessels and nonpressure vessel type tanks and associated secondary barrier, as defined in [§§ 38.05-4](/on/2024-09-23/title-46/section-38.05-4) and [154.7 of this chapter](/on/2024-09-23/title-46/section-154.7), and their parts constructed of carbon and alloy steels which are stressed at operating or hydrostatic test temperatures below 0 °F.

(2)

(i) The service temperature is the minimum temperature of a product at which it may be contained, loaded and/or transported. However, the service temperature must in no case be taken higher than given by the following formula:

Formula 1 to [§ 54.25-10(a)(2)(i)](/on/2024-09-23/title-46/section-54.25-10#p-54.25-10(a)(2)(i))

ts = tw − 0.25(tw − tB)

where:

ts = Service temperature.

tw = Boiling temperature of gas at normal working pressure of container but not higher than + 32 °F.

tB = Boiling temperature of gas at atmospheric pressure.

(ii) Only temperatures due to refrigerated service usually need to be considered in determining the service temperature, except pressure vessel type cargo tanks operating at ambient temperatures must meet [paragraph (d)](/on/2024-09-23/title-46/section-54.25-10#p-54.25-10(d)) of this section. “Refrigerated service”, as used in this [paragraph (a)(2)(ii)](/on/2024-09-23/title-46/section-54.25-10#p-54.25-10(a)(2)(ii)), means a service in which the temperature is controlled by the process and not by atmospheric conditions.

(b) *Specifications.* Materials used in the construction of vessels to operate below 0 °F (but not below the designated minimum service temperature) must conform to a specification given in table UCS-23 in Section VIII of the ASME BPVC (incorporated by reference; see [§ 54.01-1](/on/2024-09-23/title-46/section-54.01-1)) and the following additional requirements:

Note 1 to paragraph (b) introductory text:

For high alloy steels refer to [§ 54.25-15](/on/2024-09-23/title-46/section-54.25-15). For heat treated steels refer to [§ 54.25-20](/on/2024-09-23/title-46/section-54.25-20).

(1)

(i) For minimum service temperatures not lower than −67 °F, ferritic steels must be made with fine grain practice and must have an austenitic grain size of 5 or finer, and must be normalized. Consideration will be given to other heat treatments; refer to [§ 57.03-1(d) of this subchapter](/on/2024-09-23/title-46/section-57.03-1#p-57.03-1(d)). Plate for pressure vessel applications must conform to the requirements of ASTM A20/A20M (incorporated by reference, see [§ 54.01-1](/on/2024-09-23/title-46/section-54.01-1)). It may be produced by the open hearth, basic oxygen or electric furnace process and must conform to the requirements of table 1 to [§ 54.25-10(b)(1)](/on/2024-09-23/title-46/section-54.25-10#p-54.25-10(b)(1)). (Other alloying elements may only be present in trace amounts.)

(ii) Mechanical properties must be within the following limits:

(A) Ultimate strength: 58,0001-85,0001psig.

(B) Yield strength: Minimum 35,000 psig. Maximum 80 percent of ultimate.

(C) Elongation minimum: 20 percent in 8 inches, or 24 percent in 2 inches, or 22 percent in 5.65 √A, where “A” is the test specimen cross sectional area.

Table 1 to [§ 54.25-10](/on/2024-09-23/title-46/section-54.25-10)(b)(1)

| Minimum service1 temperature °F | Max. C1 percent | Manganese range1 percent |
| --- | --- | --- |
| −30 | 0.20 | 0.70-1.35 |
| −50 | .16 | 1.15-1.50 |
| −67 | .12 | 1.30-1.60 |
| | | |
| --- | --- | --- |
| 1 At service temperatures intermediate between those specified, intermediate amounts of carbon and manganese will be allowed (in proportion to the actual service temperature variation from that listed), provided all other chemical and mechanical properties specified for steels in this temperature range are satisfied. | | |

Table 2 to [§ 54.25-10](/on/2024-09-23/title-46/section-54.25-10)(b)(1)

| | Range percent |
| --- | --- |
| Si | 0.10-0.50 Maximum. |
| S | 0.035. |
| P | 0.035. |
| Ni | 0.80. |
| Cr | 0.25. |
| Mo | 0.08. |
| Cu | 0.035. |
| Nb | 0.05. |
| V | 0.08. |

(2) For minimum service temperature below −67 °F, but not below the designated minimum service temperature, ferritic steels must be normalized, low carbon, fully killed, fine grain, nickel alloy type, conforming to any one of the specifications in table 3 to [§ 54.25-10(b)(2)](/on/2024-09-23/title-46/section-54.25-10#p-54.25-10(b)(2)). Consideration will be given to other heat treatments. Refer to [§ 57.03-1(d) of this subchapter](/on/2024-09-23/title-46/section-57.03-1#p-57.03-1(d)) for quenched and tempered steels. The ultimate and yield strengths must be as shown in the applicable specification and must be suitable to the design stress levels adopted. The service temperature must not be colder than the minimum specified in table 3 to [§ 54.25-10(b)(2)](/on/2024-09-23/title-46/section-54.25-10#p-54.25-10(b)(2)) for each steel.

Table 3 to [§ 54.25-10](/on/2024-09-23/title-46/section-54.25-10)(b)(2)

| Steel | Minimum service temperature |
| --- | --- |
| A-203, 2.25 percent, Ni, normalized | −80 °F for Grade A. −75 °F for Grade B. |
| A-203, 3.5 percent, Ni, normalized | −130 °F for Grade D. −110 °F for Grade E. |
| 5 percent Ni, normalized | Dependent on chemical and physical properties. |

(3) The materials permitted under [paragraphs (b)(1)](/on/2024-09-23/title-46/section-54.25-10#p-54.25-10(b)(1)) and [(2)](/on/2024-09-23/title-46/section-54.25-10#p-54.25-10(b)(2)) of this section must be tested for toughness in accordance with and must satisfy the applicable requirements of subpart 54.05.

(4) Welded pressure vessels or nonpressure vessel type tanks and associated secondary barriers, as defined in [§ 38.05-4](/on/2024-09-23/title-46/section-38.05-4) of subchapter D of this chapter must meet the toughness requirements of subparts 57.03 and 57.06 of this subchapter with regard to weld procedure qualifications and production testing.

(5) The material manufacturer's identification marking required by the material specification must not be die-stamped on plate material less than one-fourth inch in thickness.

(c) *Design.* Pressure vessels must meet the requirements for Class I-L and II-L construction. (See table 2 to [§ 54.01-5](/on/2024-09-23/title-46/section-54.01-5) for applicable requirements). Except as permitted by [§ 54.05-30](/on/2024-09-23/title-46/section-54.05-30), the allowable stress values used in the design of low temperature pressure vessels may not exceed those given in table UCS-23 of Section VIII of the ASME BPVC for temperatures of 0 °F to 650 °F. For materials not listed in this table allowable stress values are determined in accordance with appendix P of Section VIII of the ASME BPVC.

(d) *Impact tests.* Weldments and all materials used in pressure vessel type cargo tanks operating at ambient temperatures and constructed of materials listed in table UCS-23 must pass Charpy impact tests in accordance with UG-84 at a temperature of −20 °F or colder, except as provided by [paragraphs (d)(1)](/on/2024-09-23/title-46/section-54.25-10#p-54.25-10(d)(1)), [(2)](/on/2024-09-23/title-46/section-54.25-10#p-54.25-10(d)(2)), and [(3)](/on/2024-09-23/title-46/section-54.25-10#p-54.25-10(d)(3)) of this section.

(1) Charpy impact tests are not required for any of the following ASTM materials if the thickness for each is 5⁄8 inch or less, unless otherwise indicated:

(i) A-182, normalized and tempered.

(ii) A-302, Grades C and D.

(iii) A-336, Grades F21 and F22 that are normalized and tempered.

(iv) A-387, Grades 21 and 22 that are normalized and tempered.

(v) A-516, Grades 55 and 60.

(vi) A-533, Grades B and C.

(vii) All other plates, structural shapes and bars, and other product forms, except for bolting, if produced to a fine grain practice and normalized.

(2) Charpy impact tests are not required for any of the following ASTM materials if the thickness for each is 1.25 inch or less:

(i) A-203.

(ii) A-508, Class 1.

(iii) A-516, normalized.

(iv) A-524.

(v) A-537.

(vi) A-612, normalized.

(vii) A-662, normalized.

(viii) A-724, normalized.

(3) Charpy impact tests are not required for any of the following bolt materials:

(i) A-193, Grades B5, B7, B7M, and B16.

(ii) A-307, Grade B

(iii) A-325, Type 1.

(iv) A-449.

[CGFR 68-82, [33 FR 18828](https://www.federalregister.gov/citation/33-FR-18828), Dec. 18, 1968, as amended by CGFR 69-127, [35 FR 9977](https://www.federalregister.gov/citation/35-FR-9977), June 17, 1970; CGD 73-133R, [39 FR 9178](https://www.federalregister.gov/citation/39-FR-9178), Mar. 8, 1974; CGD 74-289, [44 FR 26007](https://www.federalregister.gov/citation/44-FR-26007), May 3, 1979; CGD 77-069, [52 FR 31626](https://www.federalregister.gov/citation/52-FR-31626), Aug. 21, 1987; CGD 85-061, [54 FR 50964](https://www.federalregister.gov/citation/54-FR-50964), Dec. 11, 1989; USCG-1999-5151, [64 FR 67178](https://www.federalregister.gov/citation/64-FR-67178), Dec. 1, 1999; USCG-2000-7790, [65 FR 58460](https://www.federalregister.gov/citation/65-FR-58460), Sept. 29, 2000; USCG-2003-16630, [73 FR 65170](https://www.federalregister.gov/citation/73-FR-65170), Oct. 31, 2008]