If a tank vessel having a COW system under Sec. 157.10(e), Sec. 157.10a(a)(2), or Sec. 157.10c(b)(2) carries more than one grade of crude oil, the COW system must be capable of washing the cargo tanks with the grades of crude oil that the vessel carries. [CGD 82-28, 50 FR 11627, Mar. 22, 1985]