46 C.F.R. § 39.2001 – Vapor collection system—TB/ALL.

(a) Vapor collection piping must be fixed piping and the vessel's vapor connection must be located as close as practicable to the loading manifold, except—
1. (1) As allowed by the Commandant; and
2. (2) A vessel certificated to carry cargo listed in 46 CFR, part 151, Table 151.05 or part 153, Table 1 may use flexible hoses no longer than three meters (9.84 feet) for interconnection between fixed piping onboard the vessel to preserve segregation of cargo systems. These flexible hoses must also meet the requirements in paragraph (i) of this section, excluding paragraph (i)(5), and meet the following additional requirements:
  1. (i) The installation of flexible hoses must include an isolation valve mounted on the tank side of the connection; and
  2. (ii) Hose connections permitted under paragraph (a)(2) of this section are exempt from the requirements of paragraph (h) of this section.
(b) When collecting incompatible vapors simultaneously, vapors must be kept separate throughout the entire vapor collection system.
(c) Vapor collection piping must be electrically bonded to the hull and must be electrically continuous.
(d) The vapor collection system must have a mechanism to eliminate liquid condensation, such as draining and collecting liquid from each low point in the line.
(e) For a tankship that has an inert gas system, a mechanism must be in place to isolate the inert gas supply from the vapor control system (VCS). The inert gas main isolation valve required by chapter II-2, Regulation 62.10.8 of SOLAS (incorporated by reference, see 46 CFR 39.1005), may be used to satisfy this requirement.
(f) The vapor collection system must not interfere with the proper operation of the cargo tank venting system.
(g) The tank vessel owner or operator must install an isolation valve capable of manual operation. It must be located at the vessel vapor connection and must clearly show whether the valve is in the open or closed position via an indicator, valve handle, or valve stem.
(h) The last 1.0 meter (3.3 feet) of vapor piping upstream of the vessel vapor connection and each end of a vapor hose must be—
1. (1) Painted in the sequence of red/yellow/red. The width of the red bands must be 0.1 meter (0.33 foot) and the width of the middle yellow band must be 0.8 meter (2.64 feet); and
2. (2) Labeled with the word “VAPOR” painted in black letters at least 50.8 millimeters (2 inches) high.
(i) Hoses that transfer vapors must meet the following requirements:
1. (1) Have a design burst pressure of at least 25 pounds per square inch gauge (psig);
2. (2) Have a maximum allowable working pressure no less than 5 psig;
3. (3) Be capable of withstanding at least a 2.0 pounds per square inch (psi) vacuum without collapsing or constricting;
4. (4) Be electrically continuous with a maximum resistance of 10,000 ohms;
5. (5) Have flanges with—
  1. (i) A bolthole arrangement complying with the requirements for 150 pound class ANSI B16.5 flanges (incorporated by reference, see 46 CFR 39.1005); and
  2. (ii) One or more 15.9 millimeter (0.625 inch) diameter hole(s) located midway between boltholes and in line with the bolthole pattern; and
6. (6) Be abrasion and kinking resistant.
(j) Each vessel vapor connection flange face must have a permanent stud projecting outward that has a 12.7 millimeter (0.5 inch) diameter and is at least 25.4 millimeters (1 inch) long. It must be located at the top of the flange face, midway between boltholes, and in line with the bolthole pattern.
(k) Quick disconnect couplings (QDCs) may be used instead of flanges at the flexible hose connection and fixed piping on tankships provided they meet ASTM F1122 (incorporated by reference, see 46 CFR 39.1005) and are designed as “Standard Class QDC.”
(l) Hose saddles that provide adequate support to prevent kinking or collapse of hoses must accompany vapor hose handling equipment.
(m) For cargoes that have toxic properties, listed in 46 CFR Table 151.05 with the “Special requirements” column referring to 46 CFR 151.50-5, an overfill alarm and shutdown system that meet the requirements of 46 CFR 39.2007(a), 39.2009(a), or 39.2009(b) must be used for primary overfill protection. If the vessel is also equipped with spill valves or rupture disks, their setpoints must be set higher than the vessel's pressure relief valve setting as required by 46 CFR 39.2009(a)(3).