33 CFR § 183.516 - Cellular plastic used to encase fuel tanks.

---
identifier: "/us/cfr/t33/s183.516"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "33 CFR § 183.516 - Cellular plastic used to encase fuel tanks."
title_number: 33
title_name: "Navigation and Navigable Waters"
section_number: "183.516"
section_name: "Cellular plastic used to encase fuel tanks."
chapter_name: "COAST GUARD, DEPARTMENT OF HOMELAND SECURITY"
subchapter_number: "S"
subchapter_name: "BOATING SAFETY"
part_number: "183"
part_name: "BOATS AND ASSOCIATED EQUIPMENT"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "46 U.S.C. 4302; Pub. L. 103-206, 107 Stat. 2439; and Department of Homeland Security Delegation No. 0170.1, para. II, (92)(b). Subpart E is also authorized by Pub. L. 114-120, 130 Stat. 27"
regulatory_source: "CGD 72-61R, 37 FR 15782, Aug. 4, 1972, unless otherwise noted."
cfr_part: "183"
---


# 183.516 Cellular plastic used to encase fuel tanks.

(a) Cellular plastic used to encase metallic fuel tanks must:

(1) Not change volume by more than five percent or dissolve after being immersed in any of the following liquids for 24 hours at 29 °C:

(i) Reference fuel B ASTM D 471 (incorporated by reference, see § 183.5).

(ii) No. 2 reference oil of ASTM D 471 (incorporated by reference, see § 183.5).

(iii) Five percent solution of trisodium phosphate in water; and

(2) Not absorb more than 0.12 pound of water per square foot of cut surface, measure under Military Specification MIL P-21929B.

(b) Non-polyurethane cellular plastic used to encase metallic fuel tanks must have a compressive strength of at least 60 pounds per square inch at ten percent deflection measured under ASTM D 1621 (incorporated by reference, see § 183.5), “Compressive Strength of Rigid Cellular Plastics”.

(c) Polyurethane cellular plastic used to encase metallic fuel tanks must have a density of at least 2.0 pounds per cubic foot, measured under ASTM D 1622 (incorporated by reference, see § 183.5), “Apparent Density of Rigid Cellular Plastics.”

[CGD 74-209, 42 FR 5950, Jan. 31, 1977, as amended by CGD 77-98, 42 FR 36253, July 14, 1977; CGD 81-092, 48 FR 55737, Dec. 15, 1983; USCG-2000-7223, 65 FR 40059, June 29, 2000]