(a) Process of manufacture.- The castings shall be cast from metal melted or refined in any metallurgical plant other than an iron ore smelting furnace, for the use of which furnace permission in writing must be received from the Inspecting Authority.

(b) Chemical Composition.- The composition of the iron as cast shall be left to the discretion of the manufacturer but the maximum percentage of phosphorus or sulphur or both may be specified by the Inspecting Authority, if he so desires.

(c) Moulding.- The castings shall be accurately moulded in accordance with the pattern or working drawings supplied by the Inspecting Authority with the addition of such letters, figures or marks as may be specified and the drawings shall include the tolerances specified in the Regulations.

Freedom from defects.- The castings shall be sound, clean out of twist and free from blow holes distortion and all surface and other defects. They shall be well dressed or fettled and shall be machinable by normal methods.