U.S. Code of Federal Regulations
Regulations most recently checked for updates: Aug 28, 2025
(a) A sounding tube installed as a restricted gauge must extend to within one meter (approx. 39.4 in.) of the bottom of the tank.
(b) A sounding tube must not be installed on a tank whose relief valve setting exceeds 28 kPa (approx. 4 psig) unless it is specifically permitted by the Commandant (CG-ENG).
(c) A sounding tube must have no perforations in the tube wall.
