Paragraph 10 Construction, etc., of system

so placed or protected as not to be exposed to accidental damage and shall be soundly and properly constructed of suitable and well-finished materials capable of withstanding the loads and stresses likely to be met with in operation and shall be maintained in an efficient, safe and clean condition; and

so designed and constructed that leakage of gas is not likely to occur under normal working conditions, whether or not the engine is running.