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tensile and one bend test shall be taken from each forging; but if the weight ex- ceeds 3 tons a tensile and a bending test shall be taken from each end. 29. Preparation of Test Pieces.--The test pieces shall be cut from a part of the forging of sectional dimensions not less than those of the body of the forging and shall be machined to size without further forging down. They shall be cut off until the annealing has been complet- ed and they have, subsequent thereto, been stamped by the surveyor. 30. Tensile Strength and Elongation. --The tensile strength of steel forgings shall not exceed 40 tons per sq. in.; and the elongation, measured on the appro- priate standard test piece C, D or E, shall not be less 17 per cent for 40- ton steel; and in no case may the sum of the tensile strength and the corresponding elongation be less than 57. 31. Bend Tests--The bending test pieces must withstand being bent through an angle of 180 deg. without fracture, the internal radius of the bend being not greater than that specified below: Internal Radius of Test Piece After Bending. Maximum Specified Tensile Strength of Forging. Up to 32 tons per square inch % in. Above 32 tons and up to 36 tons per square inch........ % in. Above 36 tons and up to 40 fous: per square. inch... . 5% in. STEEL CASTINGS. 32. General.--All steel castings shall be thoroughly annealed at a uniform tem- perature, and shall be allowed to cool down prior to removal from the anneal- ing furnace; and if subsequently heated, with the surveyor's approval, shall again be similarly annealed, if required by the surveyor. Test pieces shall not be cut off until stamped by the surveyor, which shall not be done until the castings have been annealed. 33. Number of Tests----No tests need be made from unimportant steel castings or from steel castings which are used for articles usually made of cast iron, if the scantlings are not materially reduced be- low what would be required if cast iron were used. All other steel castings shall be tested as follows: At least one tensile and one bending test shall be made from the castings from each charge; and, where a casting is made from more than one charge; at least four tensile and four bending tests shall be made from pieces cast as far apart as possible on the cast- ing and as near the top and the bottom respectively as practicable. When more than one casting is made from one charge, at least one tensile and one bend- ing test shall be made from the castings run from one common pouring head; but Separate tests shall be made from each casting or set of castings run from each Separate pouring head. Small castings may, however, be dealt with in accord- ance with the provisions of section 6. 34. Tensile Strength and Elongation. "TAE. Marine REVIEW --The tensile strength may range from 26 to 40 tons per sq. in., with an elongation measured on the standard test piece C, D, or E of not less than 15 per cent. But if the castings are to be used for the more important pieces of machinery, such as pistons, etc, or for articles usually made of wrought material, the elongation must not be less than 20 per cent, where the corresponding tensile strength is be- tween 26 and 35 tons per sq. in. 35. Bend Tests--The bending test pieces must withstand being bent, with- out fracture, though an angle of 60 deg. if the 'tensile strength is be- tween 35 and 40 tons per sq. in.; and, in the case of other castings, through an angle of 90 deg. But if they are required to be of the superior quality referred to above, the angle must not be less than 120 degs. The internal radius of the bend in 47 each case may not be greater than 1 in. 36. Repeal--tThese instructions super- sede those contained in the following clauses of the regulations as to the survey of the hull, equipments, and machinery of steamships carrying passengers, 1905 edi- tion--viz., 92, 93, 94 down to the words "shaping machine;" 95, 96, 97, from the words "The following proportion" to the words "in a length of 10 in.," in the fourth line on page 62; the four lines commencing with the words "The tensile strength of strips;" and from the words "The tensile strength of rivet bars" to the end of the paragraph. 37. Circulation of Instructions. = is veyors are requested to bring these in- structions to the notice of persons inter- ested. H. LLEWELLYN SMITH, Secretary, WALTER J. Howe Lt, Assistant Sec'y. The Practical Proportioning © the Re- action Steam-Turbine. _ - (From Engineering.) It has been generally known for some time past that many builders of the com- pound reaction steam-turbine do not in general attempt any very detailed analy- sis of the action of the steam as it passes through the blading, but determine the proportions necessary by certain simple formulae largely empirical in character. For example: a rule for deciding upon the number of rows of blades which has been very largely worked to is s°n = constant, where s denotes the speed of the moving blades in feet per second, and m the num- ber of rows of blades on the rotor; that is to say, half the number of stages. There appears to be some difference in the practice of designers using this rule. Some take for s the speed of the blades at their roots; that is to say, the surface speed of the drum; while others denote by s the mean blade speed. The former practice is the simpler, but the latter is somewhat the more logical. The above rule has already been given in Mr. Sothern's excellent little work on the "Marine Steam-Turbine,' but the method of using it is not very clearly explained. He states that the value of the constant is 1,500,000, and this figure agrees very well with the proportions actually adopt- ed in marine practice. For example, the same author gives the following particu- lars of the blading of a cross-channel steamer, the turbines of which were de- ~ signed to make 500 R. P. M.: He: 48 in. ber, Diameétera ote imum. ei. sa 68 in. Total number of rows of blades On "ROO a eee aun eras 48 48 Blade léngths...Group t 1% in. 1% in. Group 2 2. ine 2) ine Group III. 234 in. 2% in. Group? TV, 5 45) in. 4s an, Group Vv. ; 5¥% in. Group VI. Gc, Group VII. 2) oie Group VIII. 85 4in. The surface speed of the drum is here 104.7 ft. per second. As there are two low-pressure turbines, the high-pressure is intended to do only one-third of the. total work, and hence its rutor has only one-third the total number of rows of blades given by the formula. The con- stant here is 1,600,000. So that we have n X 107.4' = 1,600,000, whence u == 144 nearly, one-third of which is 48, which is the actual figure. For the low-pressure turbine s = 148.4, whence ~--/+aro. Say, 72, (148.4)? The low-pressure turbines are intended to do two-thirds the total work, and hence the actual number of rows pro- vided is 2/3 X 72 = 48. It will be seen that the low pressure drum has a dia- meter equal to that of the high-pressure drum multiplied by V2. This rule for sticcessive drum diameters is very com- monly worked to both in marine and elec- tric-light practice. As another example of a marine tur- bine we give below the data for a ship having two high-pressure and two low- pressure turbines. Here the drum di- ameters are 68 in. and 92 1 in. repens