The inspection, tests, stamping, and reports for pressure vessels must be as required by paragraphs UG-90 through UG-103 and UG-115 through UG-120 of Section VIII of the ASME BPVC (incorporated by reference; see § 54.01-1) except as noted otherwise in this subpart.

(a) Only marine inspectors will apply the Coast Guard Symbol. They will not apply any other code symbol to pressure vessels.

(b) All pressure vessels not exempted under provisions of § 54.01-15 must be subject to shop inspection by a marine inspector referring to procedures outlined in UG-92 through UG-103 of Section VIII of the ASME BPVC (incorporated by reference; see § 54.01-1) and §§ 50.30-10, 50.30-15, and 50.30-20 of this subchapter. The marine inspector will then stamp the vessel with the Coast Guard Symbol.

(c) Pressure vessels exempted under provisions of § 54.01-15, except as provided in paragraph (d) of this section, are not required to be stamped with the Coast Guard Symbol.

(d) Pressure vessels described in § 54.01-5(c)(3), except pressure vessels in systems regulated under subpart 58.60 of this subchapter, must be visually examined by a marine inspector prior to installation. The marine inspector also reviews the associated plans and manufacturers' data reports. If, upon inspection, the pressure vessel complies with the applicable requirements in § 54.01-5, the marine inspector stamps the pressure vessel with the Coast Guard Symbol.

(a) The maximum allowable working pressure for a vessel is the maximum pressure permissible at the top of the vessel in its normal operating position at the designated coincident temperature specified for that pressure. It is the least of the values found for maximum allowable working pressure for any of the essential parts of the vessel by the principles given in paragraph (b) of this section and adjusted for any difference in static head that may exist between the part considered and the top of the vessel. (See appendix 3 of Section VIII of the ASME BPVC (incorporated by reference; see § 54.01-1.))

(b) The maximum allowable working pressure for a vessel part is the maximum internal or external pressure, including the static head hereon, as determined by the rules and formulas in Section VIII of the ASME BPVC, together with the effect of any combination of loadings listed in UG-22 of Section VIII of the ASME BPVC (see § 54.01-30) that are likely to occur, or the designated coincident operating temperature, excluding any metal thickness specified as corrosion allowance. (See UG-25 of Section VIII of the ASME BPVC.)

(c) Maximum allowable working pressure may be determined for more than one designated operating temperature, using for each temperature the applicable allowable stress value.

(a) All pressure vessels must satisfactorily pass the hydrostatic test prescribed by this section, except those pressure vessels noted under § 54.10-15(a).

(b) The hydrostatic-test pressure must be at least one and three-tenths (1.30) times the maximum allowable working pressure stamped on the pressure vessel, multiplied by the ratio of the stress value “S” at the test temperature to the stress value “S” at the design temperature for the materials of which the pressure vessel is constructed. The values for “S” must be taken from tables UCS 23, UNF 23, UHA 23, or UHT 23 of Section VIII of the ASME BPVC (incorporated by reference, see § 54.01-1). The value of “S” at test temperature must be that taken for the material of the tabulated value of temperature closest to the test temperature. The value of “S” at design temperature must be as interpolated from the appropriate table. No ratio less than one must be used. The stress resulting from the hydrostatic test must not exceed 90 percent of the yield stress of the material at the test temperature. External loadings, which will exist in supporting structure during the hydrostatic test, should be considered. The design must consider the combined stress during hydrostatic testing due to pressure and the support reactions. This stress must not exceed 90 percent of the yield stress of the material at the test temperature. In addition, the adequacy of the supporting structure during hydrostatic testing should be considered in the design.

(c) The hydrostatic test pressure must be applied for a sufficient period of time to permit a thorough examination of all joints and connections. The test must not be conducted until the vessel and liquid are at approximately the same temperature.

(d) Defects detected during the hydrostatic test or subsequent examination must be completely removed and then inspected. Provided the marine inspector gives their approval, they may then be repaired.

(e) Vessels requiring stress relieving must be stress relieved after any welding repairs have been made. (See UW-40 of Section VIII of the ASME BPVC.)

(f) After repairs have been made the vessel must again be tested in the regular way, and if it passes the test, the marine inspector may accept it. If it does not pass the test, the marine inspector can order supplementary repairs, or, if in their judgment the vessel is not suitable for service, they may permanently reject it.

(a) Pneumatic testing of welded pressure vessels is permitted only for those units which are so designed and supported that they cannot be safely filled with water, or for those units which cannot be dried and are to be used in a service where traces of the testing medium cannot be tolerated.

(b) Proposals to pneumatically test must be submitted to the cognizant Officer in Charge, Marine Inspection, for approval.

(c) Except for enameled vessels, for which the pneumatic test pressure must be at least equal to, but need not exceed, the maximum allowable working pressure to be marked on the vessel, the pneumatic test pressure must be at least equal to one and one-tenth (1.10) times the maximum allowable working pressure to be stamped on the vessel multiplied by the lowest ratio (for the materials of which the vessel is constructed) of the stress value “S” for the test temperature of the vessel to the stress value “S” for the design temperature (see UG-21 of Section VIII of the ASME BPVC (incorporated by reference; see § 54.01-1)). In no case must the pneumatic test pressure exceed one and one-tenth (1.10) times the basis for calculated test pressure as defined in UA-60(e) of Section VIII of the ASME BPVC.

(d) The pneumatic test of pressure vessels must be accomplished as follows:

(1) The pressure on the vessel must be gradually increased to not more than half the test pressure.

(2) The pressure will then be increased at steps of approximately one-tenth the test pressure until the test pressure has been reached.

(3) The pressure will then be reduced to the maximum allowable working pressure of the vessel to permit examination.

(e) Pressure vessels pneumatically tested must also be leak tested. The test must be capable of detecting leakage consistent with the design requirements of the pressure vessel. Details of the leak test shall be submitted to the Commandant for approval.

(f) After satisfactory completion of the pneumatic pressure test, the vessel may be stamped in accordance with § 54.10-20. A marine inspector must observe the pressure vessel in a loaded condition at the first opportunity following the pneumatic test. The tank supports and saddles, connecting piping, and insulation if provided must be examined to determine if they are satisfactory and that no leaks are evident.

(g) The pneumatic test is inherently more hazardous than a hydrostatic test, and suitable precautions must be taken to protect personnel and adjacent property.

(a) Pressure vessels (Replaces UG-116, except paragraph (k), and UG-118). Pressure vessels that are required by § 54.10-3 to be stamped with the Coast Guard Symbol must also be stamped with the following information:

(1) Manufacturer's name and serial number.

(2) Coast Guard number, see § 50.10-30 of this subchapter (only applicable to pressure vessels inspected as required by § 54.10-3(b)).

(3) Coast Guard Symbol, which is affixed only by the marine inspector.

(4) Maximum allowable working pressure __ kPa (__ psig) at __ °C (__ °F).

(5) Class.

(6) Minimum design metal temperature, if below −18 °C (0 °F).

(7) Water capacity in liters (U.S. gallons), if a cargo-carrying pressure vessel.

(b) Multichambered pressure vessels (Replaces UG-116(k)). In cases where more than one pressure vessel is involved in an integral construction, as with a heat exchanger, the manufacturer may elect to class the component pressure vessels differently. In such cases they must stamp the combined structures as required in paragraph (a) of this section with information for each pressure vessel. Where an item for stamping is identical for both vessels, as with name and address of manufacturer, it need not be duplicated. However, where differences exist, each value and the vessel to which it applies shall be clearly indicated.

(c) Stamping data (Replaces UG-117). Except as noted in paragraph (d) of this section, the data must be stamped directly on the pressure vessel. The data must be legibly stamped and must not be obliterated during the service life of the pressure vessel. In the event that the portion of the pressure vessel upon which the data is stamped is to be insulated or otherwise covered, the data must be reproduced on a metal nameplate. This plate must be securely attached to the pressure vessel. The nameplate must be maintained in a legible condition such that it may be easily read.

(1) Those parts of pressure vessels requiring Coast Guard shop inspection under this part which are furnished by other than the shop of the manufacturer responsible for the completed vessel must be stamped with the Coast Guard Symbol, the Marine Inspection Office identification letters (see § 50.10-30 of this subchapter) and the word “Part”, the manufacturer's name and serial number, and the design pressure.

(2) [Reserved]

(d) Thin-walled vessels (Modifies UG-119). In lieu of direct stamping on the pressure vessel, the information required by paragraph (a) of this section must be stamped on a nameplate permanently attached to the pressure vessel when the pressure vessel is constructed of—

(1) Steel plate less than one-fourth inch thick; or

(2) Nonferrous plate less than one-half inch thick.

(a) The Manufacturers' data report form, as provided by the Coast Guard, must be completed in duplicate and certified by the manufacturer for each pressure vessel required to be shop inspected under these regulations. The original of this form must be delivered to the Coast Guard inspector.

(b) Data forms for those parts of a pressure vessel requiring inspection, which are furnished by other than the shop of the manufacturer responsible for the completed unit, must be executed in triplicate by the manufacturer of the parts. The original and one copy must be delivered to the Coast Guard inspector who must forward one copy of the report to the Officer in Charge, Marine Inspection, having cognizance over the final assembly. These partial data reports, together with the final inspection and tests, must be the final Coast Guard inspector's authority to apply the Coast Guard symbol and number. A final data report must be executed by the manufacturer or assembler who completes the final assembly and tests.

(c) If a pressure vessel is required to be inspected in accordance with § 54.10-3(c), the manufacturer's data reports required by UG-120 must be made available to the Coast Guard inspector for review prior to inspection of the pressure vessel.