What is NOT a requirement of cargo piping installed in tank vessels carrying grade D or E cargo ONLY?

A
The cargo piping system shall be fixed.
B
Flanged joints shall be used for pipe sizes exceeding 2 inches in diameter.
C
Piping through bunker spaces may be run through a pipe tunnel.
D
Connections at bulkheads must be made so that the plating does not form part of a flanged joint.
E