23. An inspector or a person to whom the Minister has delegated powers may(1) enter any place where pressure vessels are constructed or installed, to inspect them;
(2) take, without charge, for analysis, samples of materials used in the manufacture or use of a pressure vessel; in such a case, he must inform the manufacturer or user and, if possible, return the samples to him after analysis;
(3) for purposes of control or analysis, conduct tests of a pressure vessel or order the user or the manufacturer to conduct them at his own expense;
(4) require a demonstration of the quality of the welding of a pressure vessel;
(5) require the production of a certificate prescribed by this Act;
(6) order, in writing, the manufacturer, installer or user of a pressure vessel to make the necessary changes to it within the time he indicates or, if he believes the defects constitute an imminent danger, immediately.