Code of Federal Regulations Title 46. Shipping § 46.31.10–21 Drydock examination, internal structural examination, cargo tank internal examination, and underwater survey intervals—TB/ALL

(a) Except as provided in paragraphs (b) through (g) of this section, each tank vessel must undergo drydock, internal structural, and cargo tank internal examinations as follows:

TABLE 31.10–21(b)—FRESH WATER SERVICE VESSELS EXAMINATION INTERVALS IN YEARS

¹ Applicable to double hull tank barges (double sides, ends, and bottoms) when the structural framing is on the internal tank surface.

² Applicable to double hull tank barges (double sides, ends, and bottoms) when the structural framing is on the external tank surface accessible for examination from voids, double bottoms, and other similar spaces.

³ Applicable to single hull tank barges with independent cargo tanks where the cargo tanks are not a contiguous part of the hull structure and which has adequate clearance between the tanks and between the tanks and the vessel's hull to provide access for examination of all tank surfaces and the hull structure.

⁴ Applicable to single hull tankships and tank barges certificated for the carriage of Grade D and E cargoes only.

⁵ Applicable to double hull tank barges (double sides, ends, and bottoms) certificated for the carriage of Grade D and E cargoes only.

⁶ Applicable to single hull tank barges certificated for the carriage of asphalt only.

⁷ Applicable to double hull tank barges (double sides, ends, and bottoms) certificated for the carriage of asphalt only.

⁸ Or as specified in part 38 or 151 as applicable.

⁹ Enhanced survey requirements apply as specified in 33 CFR part 157.

(b) During each inspection or reinspection for certification, all wing voids, rakes, cofferdams, and other void spaces on tank barges must be opened and checked from on-deck for the presence of water or cargo indicating hull damage or cargo tank leakage. If water or cargo is not present, these spaces need not be gas freed, ventilated, cleaned, or otherwise prepared for personnel entry. If water or cargo is present, an internal structural examination may be required.

(c) If, during an internal structural examination, cargo tank internal examination, or underwater survey, damage or deterioration to the hull plating, structural members, or cargo tanks is discovered, the Officer in Charge, Marine Inspection, may require the vessel to be drydocked or otherwise taken out of service to further assess the extent of the damage and to effect permanent repairs.

(d) Vessels less than 15 years of age (except wooden hull vessels) that are in salt water service with a 2.5 year drydock interval (as indicated in table 31.10–21(a) of this section) or that are in fresh water service with a five year drydock interval (as indicated in table 31.10–21(b) of this section) may be considered for an underwater survey instead of alternate drydock examinations, provided the vessel is fitted with an effective hull protection system. Vessel owners or operators must apply to the Officer in Charge, Marine Inspection, for approval of underwater surveys instead of alternate drydock examinations for each vessel. The application must include the following information:

(e) Vessels otherwise qualifying under paragraph (d) of this section, that are 15 years of age or older may be considered for continued participation in or entry into the underwater survey program on a case-by-case basis, if—

(f) Each vessel which has not met with the applicable examination schedules in paragraphs (a) through (e) of this section because it is on a voyage, must undergo the required examinations upon completion of the voyage.

(g) The Commandant (CG–CVC) may authorize extensions to the examination intervals specified in paragraph (a) of this section.