(a) Where used, tank insulation shall satisfy the following requirements for combustibility, installation, and arrangement:
(1) Insulation in a location exposed to possible high temperature or source of ignition shall be either:
(i) Incombustible, complying with the requirements of subpart 164.009 of subchapter Q (Specifications) of this chapter; or,
(ii) Self-extinguishing, as determined by ASTM D 4986, “Standard Test Method for Horizontal Burning Characteristics of Cellular Polymeric Materials,” (incorporated by reference, see § 38.01-3) and covered by a suitable steel cover.
(2) Insulation in a location protected against possible ignition by enclosure in a tight steel envelope in which inert conditions are maintained need satisfy no requirement for combustibility except chemical stability.
(3) Insulation in a location protected against possible high temperature or source of ignition by continuous surrounding structural voids or ballast tanks need satisfy no requirement for combustibility except chemical stability.
(b) All insulation shall be of a vapor-proof construction, or have a vapor-proof coating of a fire-retardant material acceptable to the Commandant. Unless the vapor barrier is inherently weather resistant, tanks exposed to the weather shall be fitted with a removable sheet metal jacket of not less than 0.083-inch thick over the vapor-proof coating and flashed around all openings so as to be weathertight. Weather resistant coatings shall have sheet metal over areas subject to mechanical damage.
(c) The insulation shall be adequately protected in areas of probable mechanical damage.
(d) Insulation which forms an integral part of the secondary barrier shall meet the following additional requirements:
(1) When the secondary barrier is called upon to contain the cargo, insulating material which is contacted shall not be affected by the cargo. Samples of the insulating material shall be tested in the cargo for solubility, absorption and shrinkage. The samples shall be checked for the above effects at intervals not exceeding 1 week, for a total test period of 6 weeks.
(2) Any adhesives, sealers, coatings, or vapor barrier compounds used in conjunction with the insulating material shall be similarly tested to insure suitable cargo resistive properties.
(3) The insulation shall have sufficient mechanical strength for the proposed design. Additionally, the thermal expansion of the insulation relative to the material to which it is affixed shall be considered in the design.
(e) The insulation for the piping systems shall be at least of the “self-extinguishing” type described in paragraph (a) of this section, and comply with the requirements contained in paragraphs (b) and (c) of this section.