The following text may have been generated by Optical Character Recognition, with varying degrees of accuracy. Reader beware!

8 MARINE REVIEW. Marine Boiler Steel. It will probably be a week or ten days before an official account will be published of the meeting of the United States supervising inspectors of steam vessels, held in Washington recently. In the meantime manu facturers of boiler plate, inspectors and others will be intereeted in the suggestions made to the board by the Association of American Steel Manufacturers regarding changes in specifications for boiler steel. The circular which the steel manufacturers addressed to the board is as fol- lows: "Referring to the general rules and regulations prescribed by the board of supervising inspectors of steam vessels, as amended January and February, 1895, the Association of American Steel Manufacturers would suggest that that part of section 3, on page 14, reading as follows, be stricken out: 'To ascertain the tensile strength and other qualities of steel 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 plece pre- pared in form according to the following diagram : <A = "The length of straight part in center varying as called for by thick- ness of material as follows: The straight portion shall be in length at least eight times the width multiplied by the thickness of said part, and have a reduction of area as called for by the present rules of the board, and an elongation of at least 25 per cent. The straight part shall be of a width of linch. All test pieces of 1 inch thickness and upward shall have the straight part 8 inches in length. The ends of test pieces may be from 1% to 2 inches in width, and from 4 to 6 inches long, as may be desired.'" i "Now in lieu of the foregoing we suggest that paragraphs Nos. 1, 2 and 3 be substituted. , STEEL BOILER PLATE. "Paragraph No.1. All steel for marine boiler plates must be made by the open-hearth process and be of domestic manufacture. "Paragraph No. 2. To ascertain the tensile strength or other quali- ties of steel] plate there shall be taken from each sheet to be used in the shell or in other parts of the the boiler which are subject to tensile strain a test piece prepared in form according to Fig. 1. Wiad Ar gt "I ae Fig. 1. "Paragraph No.3. The elongation for all thicknesses shall be at least 25 per cent. and the reduction of area shall be the same as called for by the present rules of the board. The widthin all cases shall be linch. The ends of the test piece may be from 11% inches to 2 inches in width, and from 4 to 6 inches long, as may be desired. Before placing the test piece in the machine, punch marks shall be placed at intervals of linch. The length in which the elogation is measured shall be taken as nearly equally as possible on bothsides of the fracture. In plates less than inch in thickness this length shall be 2 inches. In plates 4 inch thick and up to % inch it shall be 4 inches In plates from 3% inch to 1 inch inclusive it shall be 8 inches. In plates over | inch it shall be 6inches, It is also suggested that additional requirements be incor- porated in the specifications as embodied in paragraph No. 4. _ "Paragraph No.4. The maximum figure which can be stamped upon the steel as indicating its tensile strength shall be 60,000 pounds per square inch and the factor of safety in all cases shall be five. 'This association would also recommend that your board placea limit upon the allowable content of phosphorus and sulphur in boiler plate. Paragraph No. 4 is of pre-eminent importance, and it is necessary to explain its bearing and force. Under the present law there is nothing to prevent a boiler maker from ordering steel with a tensile strength of 70,080 pounds, or even 80,000 pounds, per square inch, and using a pro- portionately high steam pressure, The cost of such steel to the manu- facturer is no greater than a softer metal, so that a protest against it does not arise from any mercenary motives, but itis the unanimous Opinion of the members of the Association of American Steel Manufacturers that not only is such an increase in steam power unwarranted and dangerous, but that such hard steel is unfit for steam boilers, no matter what the pressure may be. The temptation to order such material will be re- moved if no increase in steam pressure is allowed for an increase in tensile strength above 60,000 pounds per square inch. The placing of the factor of safety at five instead of six, as at present, may seem to bea ----= sacrifice of safety to expediency. That such is not the case wij] be see from a consideration of the following facts: The practice of the be rad in regard to the allowable limits of steam pressure is founded ong results deduced from the old system of grooved test, such as is shown jy Fig. 2. amo TG "Tt has been an accepted fact for many years that such a test gives, tensile strength about 10,000 pounds per square inch above that which ; would be obtained from a parallel sided test piece, such as is shown in Fig. 1. In other words, if the grooved test piece gave an ultimate strength of 60,000 pounds per square inch, then the real strength of the piece would be about 50,000 pounds per square inch, when tested in , strip with parallel sides, this being now the universal and accepted method throughout the engineering world. Granting these premises, it follows without argument that the stress per unit of section, which is allowable for a 60,000 pound steel when tested in a grooved section, js allowable for a 50,000 pound steel when tested in a parallel section, The allowable stress per unit of section is to some extent a matter of egt, mate and opinion, but it has been proven by the long and happy record of our marine boilers that the old requirement of your board was emi: nently safe. This requirement called for a factor of safety which, on steel 60,000 pounds ultimate strength, as determined by the grooved tes piece, would permit a stress of 10,000 pounds per square inch. It goes without saying, therefore, that this 10,000 pounds per square inch shonlq be allowed on a steel which shows 50,000 pounds per square inch whey pulled in parallel section, which thus indicates a factor of safety of § under the modern system of tests. This change in the factor of safety will thus obviate any necessity for a change in the allowable steam preg. ure of boilers. The change is really no change at all. It is merely g new determination of a fixed point with reference to a new datum plane, "This association also recommends that your board consider the ad. -visability of limiting the allowable amounts of certain injurious ele. ments in marine boiler plate. This has become a very general custom in structural engineering. There may be some differences of opinion among metallurgists as to the exact effect of certain elements upon the properties of steel, but there is perfect unanimity in regard to the injuri- ous effect of phosphorus and sulphur. Under the present rules of the board it is perfectly possible for a manufacturer to use a metal for boil- ers which would not be accepted by the majority of engineers for the most unimportant work, and it is absolutely certain that such a clause would be a long step in the direction of a much better and safer metal, while it would not materially enhance the cost." oe Around the Lakes. The new Union line steamer that is being built by the Union Dry Dock Co. of Buffalo will be acomplete steel vessel. Only the inside finish of cabins will be of wood. ; The Jenk Ship Building Co., Port Huron, Mich., is building a new hull for the machinery of the tug Sumner. The new boat will be owned by the H. M. Loud & Sons Lumber Co., Oscoda. C. R. Jones and others of Cleveland have purchased the schooner Charles Wall from the estate of Richard Winslow, through Geo. R. Tel- ler, attorney, of Buffalo. The vessel is now undergoing repairs at Ton- awanda. ' One of the most forcible letters, from the vessel owners' standpoint, written to the commerce committee of the senate on the Detroit river bridge question, was that of Jesse H. Farwell, the well-known Detroit contractor. Osborne, Seager & Co., coal miners and coal dealers, will have in Operation in Cleveland next season acoal dock of the pocket kind, similar to those at Detour and on the Detroit river. The dock will be located just above the Superior street viaduct. Johnston Bros. of Ferrysburg Michigan have been building up of late quite an extensive business in the marine line. A late order is for 4 fire-box boiler, 834 feet in diameter and 16 feet long, to carry 150 pounds working pressure, for the Chicago tug T. T. Morford. The $940,000 judgment of Alfred Merritt of Duluth against John D. Rockefeller, resulting from the big Mesabi mining and railway deal, is now under review by the United States circuit court of appeals sitting at Duluth. Court costs and interests have already increased the amount involved to more than $1,000,000. A decision is awaited with great inter- est in Minnesota, as it is said that suits aggregating about $4,000,000 will be brought against Mr. Rockefeller if this one goes against him.