View all text of Subpart 54.25 [§ 54.25-1 - § 54.25-25]
§ 54.25-20 - Low temperature operation—ferritic steels with properties enhanced by heat treatment (modifies UHT-5(c), UHT-6, UHT-23, and UHT-82).
(a) For service temperatures below 0 °F but not below the designated minimum service temperature, steel conforming to the specifications of table 1 to § 54.25-20(a) may be used in the fabrication of pressure vessels and nonpressure vessel tanks and associated secondary barriers, as defined in § 38.05-4 of subchapter D of this chapter. The ultimate and yield strengths must be as shown in the applicable specification and must be suitable for the design stress levels adopted. The service temperature must not be colder than −320 °F. Service temperature is defined in § 54.25-10(a)(2).
Table 1 to § 54.25-20(
| Steel | Minimum service
temperature, °F | A-333, 9 percent Ni, grade 8 | −320 | A-334, 9 percent Ni, grade 8 | −320 | A-353, 9 percent Ni, double normalized and tempered | −320 | A-522, 9 percent Ni, NNT, Q and T, forging | −320 | A-553, 9 percent Ni, quenched and tempered | −320 |
|---|
(b) The materials permitted under paragraph (a) of this section must be tested for toughness in accordance with the requirements of UHT-6 of Section VIII of the ASME BPVC (incorporated by reference; see § 54.01-1) except that tests must be conducted at the temperature specified in § 54.05-6 in lieu of that in UHT-5(c) of Section VIII of the ASME BPVC. Lateral expansion in a broken Charpy V-notch specimen is illustrated in figure 1 to § 54.25-20(b) and must be measured in accordance with the procedure outlined in ASTM A370 (incorporated by reference, see § 54.01-1).
Figure 1 to § 54.20-20(b)
(c) The qualification of welding procedures, welders and weld-production testing for the steels of table 1 to § 54.25-20(a) must conform to the requirements of part 57 of this subchapter and to those of subpart 54.05 except that the acceptance criteria for Charpy V-notch testing must be in accordance with UHT-6(a)(4) of Section VIII of the ASME BPVC.
(d) The values of absorbed energy in foot-pounds and of fracture appearance in percentage shear, which are recorded for information when complying with paragraphs (b) and (c) of this section must also be reported to the marine inspector or the Commandant, as applicable.
(e) Except as permitted by § 54.05-30, the allowable stress values may not exceed those given in table UHT-23 of Section VIII of the ASME BPVC for temperatures of 150 °F and below.