addi sure. Table of pressures allowable on boilers made since February 28, 1872-Continued. boiler. plates. 20 per cent Pres- per cent Pres- per cent Pres- per cent Pres- per cent Pres- per cent addi- sure. 20 20 20 20 tional. tional. additional. sure. additional. sure. additional. sure. Pilot rules, harbors, rivers, and inland waters. Pilot rules, Western rivers. Pilot rules, Great Lakes. Rule. Page. I 93 II 99 IX 151 VIII 150 VII 149 IV 133 148 136 125 154 156 158 2 inches. Ductility and other qualities, how obtained.. Form of recording tests. Gauge for determining thickness of boiler plate. Plates, how to be stamped.. Samples, dimensions of.. Samples, pieces, how prepared. Section. 6 8 7 4 5 1 3 3 3 Tensile strength, how obtained. Tensile strength to be rated with the lowest stamp on plate.. 2 1. Every iron or steel plate intended for the construction of boilers to be used on steam vessels shall be stamped by the manufacturer in the following manner: At the diagonal corners, at a distance of about 4 inches from the edges and at or near the center of the plate, with the name of the manufacturer, the place where manufactured, and the number of pounds tensile strain it will bear to the sectional square inch. 2. Whenever inspectors shall find a plate of iron or steel with stamps differing as to the tensile strength of the material, they shall rate the tensile strength of the same in accordance with the lowest stamp found thereon. 3. To ascertain the tensile strength and other qualities of iron plate, there shall be taken from each sheet to be used in shell or other parts of boiler which are subject to tensile strain a test piece prepared in form according to the following diagram, viz: 10 inches in length, 2 inches in width, cut out in the center in the manner indicated. 1 inch. 10 inches........ All sample pieces of iron plate five-sixteenths () inch thick and under shall be 1 inch wide at reduced section; plate over fivesixteenths () inch thick shall be reduced in width at center to 93 |