126 Material used to be inspected, sta mped, etc Pun is hme nt for faulty boiler, etc ., con- struction. Process other riveting . th an Pro vis o- . Subject to approval of Board . Temporary permits. Ap proved seamless she lls. Boiler plates, etc ., inspection . Tensile stress, etc ., to be tested . Use of unappr oved material forbidden . Proviso . Small unfired pres- sure vessels exempted . Inspection at the mills, added . Official stamp of ap- prova l . Ac ceptance of, by local inspectors . 73d CONGRESS . SESS . I. CH. 61 . JUNE 13, 1933 . " SEc . 4428. All boilers and unfired pressure vessels constructed of ir on or steel plates or ot her ap proved metals for u se on vessel s subject to inspection shall be made of material that has been tested, ins pect ed, and sta mped in acco rdan ce with the req uire men ts o f this Act. " SuC . 4429 . Any person, firm, or corporation who constructs a boiler, or steam pipe connecting the boilers, or an unfired pressure vessel f or use on vessels subject t o inspec tion, of iron or s teel plat es or oth er app roved metals which have not bee n duly teste d, ins pected , and stamped according to the provisions of this Act and the require- ments of the board of supervising inspectors ; or who knowingly uses any defective material in the construction of such boiler, steam pipe, or pressure vessel ; or who drifts any rivet hole to make it come fair ; or who delivers any such boiler, steam pipe, or pressure vessel for use, knowing it to be defective in design, material, or construc- tion, shall be fined $1,000. Nothing in this Act shall be so construed as to prevent from being used on such vessels any boiler, steam generator, steam pipe, or unfired pressure vessel which may not be constructed of riveted iron or steel plates : Provided, That scientific data and facts are submitted to enable the board of supervising inspectors to satisfy themselves that such boiler, steam generator, or pressure vessel is equal in strength and as safe from explosion as one of the best quality of iron or steel plates of riveted construction Provided, however, That the Secretary of Commerce may grant permission to use any boiler, steam generator, or unfired pressure vess el no t of iron or s teel plate riv eted const ruct ion u pon" the certificate of the supervising inspector for the district wherein such boiler, steam generator, or pressure vessel is to be used, and other satisfact ory proof that the use of t he same i s safe an d efficie nt, said permit to be valid until the next regular meeting of the board of supervising inspectors who shall act thereon : Provided further, That such boilers, steam generators, or pressure vessels may be constructed with seamless shells or by means of any approved method of welding governed by the rules and regulations prescribed by the board of supervising inspectors . " SEc. 4430 . All iron or steel plates, or other material used in the construction of boilers or unfired pressure vessels for use on vessels subject to inspection shall be tested and inspected in such manner as shall be prescribed by the board of supervising inspectors and approved by the Secretary of Commerce, so as to enable the inspec- tors to ascer tain t he ten sile s trengt h, homo geneit y, tou ghness , and ability to withstand the effect of repeated heating and cooling ; and no plate or other material shall be used in the construction of such boilers or pressure vessels which has not been tested, inspected, and approved under the rules and regulations of the board of super- vising inspectors : Provided, however, That smal l unf ired pres sure vessels havin g diam eters not ex ceedin g thirt y inch es and subje ct to a maximum allowable working pressure not exceeding one hundred pounds per square inch shall be exempt from this requirement . " The Director of the Bureau of Navigation and Steamboat Inspec- tion may, under the direction of the Secretary of Commerce, detail inspectors to inspect iron or steel plates or other material at the mills where the same are manufactured ; and if such plates or mate- rial are found in accordance with the rules of the board of super- vising in spectors, the insp ector sha ll stamp the same with the initials of his name and the official stamp of the Bureau of Navigation and Steamboat Inspection, which stamp shall be authorized by the board of supervising inspectors ; and material so stamped shall be accepted by the local inspectors of the various districts as being in full com-
