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in the center of the crown sheet of each combustion chamber.

(6) Boilers of types not herein provided for shall be fitted with at least two fusible plugs of such dimensions and located in such parts of the boiler as will, in the judgment of the Officer in Charge, Marine Inspection, best meet the purposes for which they are intended.

(d) Fusible plugs shall be renewed at each annual inspection, but in cases where the plugs were installed or renewed not more than 6 months prior to the annual inspection, they may be allowed until the next following annual inspection or for a period not to exceed 18 months. In such cases, however, the inspector shall satisfy himself at the annual inspection that the plugs are in such condition as to warrant their continued use until the next annual inspection, after which the plugs shall be renewed at each and every annual inspection.

(e) Fusible plugs shall be so fitted that the smaller end of the filling is exposed to the fire, and shall be at least 1 inch higher on the water side than the plate or flue in which they are fitted.

(f) Notwithstanding anything which may be contained in this section, fusible plugs shall be so fitted that the end of the filling on the water end of the plug is not less than 1 inch above the dangerous low-water level.

(g) Each manufacturer of fusible plugs shall number all plugs in accordance with the number of the heat from which the plugs were filled. For instance, the first pouring shall be number 1, and all plugs filled from this head shall be numbered 1; the next pouring shall be number 2, and all the plugs filled from this heat shall be numbered 2, etc.

(h) The heat number shall be plainly stamped on each end of filling with numbers not less than 12 inch in height.

(i) Manufacturers of fusible plugs shall furnish the Commandant a sample plug from each heat for examination and test, but where more than 250 plugs are poured from the same heat, a sample plug shall be furnished for each 250 plugs or fraction thereof. The samples furnished shall bear the same number for any one heat and shall represent the heat from which the sample is poured.

(j) (1) In transmitting samples of fusible plugs to the Commandant, the fusible plugs and the letters of trans

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mittal shall be addressed as follows: "The Commandant (MMT), U. S. Coast Guard, Washington, D. C."

(2) One letter of transmittal shall be required for each heat. In letter of transmittal the following information shall be stated:

(i) Number of heat.

(ii) Number of fusible plugs manufactured from the heat.

(iii) Number of samples of fusible plugs from the heat transmitted.

(iv) Name of manufacturer or initials stamped on casing of plug.

(k) (1) Manufacturers of fusible plugs shall stamp on the larger end or face of the casing their name or initials for identification and shall file with the Commandant a certificate duly sworn to that such plugs are filled with tin of the character required by this subpart and made in accordance therewith.

(2) Following is a general form of affidavit to be followed by manufacturers of fusible plugs:

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(1) The certificate shall be executed by some person having authority to make the statements contained therein.

(m) On receipt of a properly executed affidavit by the Commandant, the inspectors of the Coast Guard and the merchant marine generally shall be notified.

(n) All replacement or renewal of fusible plugs shall be manufactured from acceptable heats in conformance with Subpart 162.014 of Subchapter Q (Specifications) of this chapter.

$67.50-25 Gage cocks and water glass. (a) All boilers, except flash boilers, shall

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be supplied with at least one reliable water gage, and at least three gage cocks attached directly to each boiler. When the gage glass and gage cocks are connected to the boilers by a water column there shall be three additional gage cocks inserted in the head or shell of boiler. The lower gage cock in boilers more than 48 inches in diameter shall be not less than 4 inches above the top of the flues, tubes, or combustion chambers. In boilers less than 48 inches in diameter the lower gage cock shall be not less than 21⁄2 inches above the top of the flues, tubes, or combustion chambers. A gage glass shall be considered a reliable water gage, and a float such as used on western river steamers shall be considered on such boilers as a reliable water gage: Provided, That when water-tube boilers have an efficient water column connected to the steam drum of said boiler at the top and the water manifold at the bottom, and such water column has a gage glass and three gage cocks fitted to same, and also is fitted with a valve or stopcock, both at top and bottom where the column is connected to the boiler, no gage cocks shall be required in the head or shell of the drums of such water-tube boilers.

(b) Double-end boilers shall have at least three gage cocks and one water glass at each end.

(c) In vertical boilers of the watertube type the location of the lowest gage cock shall be determined by the Officer in Charge, Marine Inspection.

§ 67.50-30 Steam gages. All boilers or sets of boilers shall have attached to them at least one gage that will correctly indicate a pressure of steam equal to 80 percent of the hydrostatic pressure applied by the inspectors.

SUBPART 67.55-EVAPORATORS, FEED-WATER HEATERS, SEPARATORS, AND STEAM TRAPS MADE OF CAST IRON AND SUBJECT TO BOILER PRESSURE

§ 67.55-1 Computations. (a) When evaporators, feed heaters, separators, and steam traps are constructed of cast iron possessing a tensile strength of not less than 20,000 pounds per square inch, the shells being cylindrical and ends flat or convex, the castings sound and of uniform thickness, the maximum allowed pressure shall be determined by the following formulas:

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P=maximum allowable pressure in pounde per square inch.

T-thickness, in inches.

D=diameter inside, in inches. When the

pressure is to be determined for a part of a flat surface which is a square, or rectangle in the flat-sface formula, the value of D used shall be the diagonal of the square or rectangle, and when the ends are bolted to the shell the value of D used shall equal the diameter of the bolt circle.

(b) The thickness of ends of evaporators, feed heaters, and separators shall be not less than % inch. To the resultant thickness obtained by the formula given above there shall be added, for cylinders having an inside diameter of 1 inch to 6 inches, inclusive, 1⁄4 inch: for cylinders having an inside diameter of over 6 inches to 15 inches, inclusive, 8 inch.

(c) All flanges shall be substantial and there shall be a good fillet all around the root, and when the ends and shell are cast solid there shall be a good and substantial fillet inside all around.

(d) The bolts or studs for the ends or doors shall not have a greater stress than 6,000 pounds per square inch, and the size of bolts or studs shall be not less than 3/4 inch in diameter.

§ 67.55-5 Evaporators. Evaporators shall be provided with an efficient safety valve of approved type, set to blow at the maximum pressure to which the evaporator will be subjected in service, and it shall be the duty of the engineer in charge of the vessel to see that such valve blows off at least once in 30 days.

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Vent piping.

68.05-30
68.05-35 Sounding pipes.
68.05-40 Welded piping.

AUTHORITY: §§ 68.01-1 to 68.05-40 issued under R. S. 4405, as amended, 4462, as amended; 46 U. S. C. 375, 416. Interpret or apply R. S. 4399, 4400, 4417, 4417a, 4418, 4421, 4426-4430, 4433, 4434, 4453, 4491, as amended, sec. 14, 29 Stat. 690, 41 Stat. 305, 49 Stat. 1544, sec. 3, 54 Stat. 346, sec. 2, 54 Stat. 1028, sec. 5, 55 Stat. 244, 245, as amended; 46 U. S. C. 361, 362, 391, 391a, 392, 399, 404-408, 411, 412, 435, 489, 366, 363, 367, 463a, 1333, 50 U. S. C. 1275; E. O. 10402, 17 F. R. 9917; 3 CFR, 1952 Supp.

SOURCE: §§ 68.01-1 to 68.05-40 contained in CGFR 52-43, 17 F. R. 9380, Oct. 18, 1952.

SUBPART 68.01-GENERAL

§ 68.01-1 Scope. (a) This part contains requirements for the various ships' piping and appurtenances.

(b) The respective piping systems installed on vessels shall have the necessary pumps, valves, regulating valves, safety valves, relief valves, flanges, fittings, pressure gages, liquid level indicators, thermometers, etc., for safe and efficient operation of the vessel.

§ 68.01-5 Definitions—(a) Piping. The word "piping" within the meaning of this subchapter, refers to fabricated pipes or tubes with flanges and fittings attached, for use in the conveyance of vapors, gases or liquids, regardless of whether the diameter is measured on the inside or the outside.

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of this chapter, they shall be accepted by inspectors of the Coast Guard.

(b) The manufacturer of valves and fittings shall file with the Commandant a certificate duly sworn to that all valves and fittings furnished by him for use on steam vessels comply with the requirements of this subchapter.

(c) After July 1, 1911, the Officer in Charge, Marine Inspection, shall refuse to allow the use of any valves or fittings on steam vessels until notified by the Commandant that such certificate is on file in his office. This shall not apply to valves and fittings installed previous to July 1, 1911.

SUBPART 68.05-DETAIL REQUIREMENTS

§ 68.05-1 Material. (a) Welded steam and water pipes may be permitted for pipe diameters from % inch inside diameter up to and including 30 inches inside diameter. The pipe shall be made

of wrought iron or mild steel, smooth, straight, and free from defects. Threaded pipe of standard thickness shall be avoided as far as possible. In steam pipes it is a very serious matter and shall not be allowed in any case on standard pipe over 5 inches in diameter. All pipe over 2 inches in diameter shall be lap-welded.

(b) Cast-steel fittings of any size or character and for any pressure and for any temperature may be used for any and all steam and feed-pipe connections, and for valves, cocks, and all appliances subject to steam or water pressure, when made by regular processes and by manufacturers who stamp such fittings and appliances with their trade-mark or identifying stamp and who guarantee the castings to possess the following physical characteristics: Tensile strength, minimum, 50,000; maximum, 78,000 pounds per square inch; elastic limit, minimum, not less than 45 percent of tensile strength; elongation in 2 inches, minimum, 25 percent. There shall be taken from each heat an annealed coupon or coupons, for the purpose of determining the physical tests, and the manufacturers shall furnish coupons to the Officer in Charge, Marine Inspection, for tests when so required. All steel castings shall be thoroughly annealed.

(c) Cast iron, semisteel, or ferrosteel, possessing a tensile strength of not less than 22,000 pounds to the sectional square inch, may be used in the construction of valves and fittings for pressures

not exceeding 300 pounds when such valves and fittings of 3 inches diameter or over are stamped with the trade-mark or identifying stamp of the manufacturer.

(d) Malleable iron possessing a tensile strength of not less than 30,000 pounds to the sectional square inch may be used in the construction of valves and fittings up to and including 6 inches in diameter, and for pressures not exceeding 300 pounds. Such valves and fittings of 3 inches diameter or over shall be extra heavy, the fitting beaded or banded, and the valves and fittings stamped with the trade-mark or identifying stamp of the manufacturer.

(e) Hard brass, bronze, and other compositions, of which 95 percent is copper, tin, and zinc, possessing a tensile strength of not less than 30,000 pounds to the square inch, may be used in the construction of all valves and fittings up to and including 12 inches in diameter. All such fittings of 3 inches in diameter or over shall be stamped with the trademark or identifying stamp of the manufacturer.

(f) The following material shall be permitted at the allowable temperatures indicated:

(1) Cast iron, malleable iron, semisteel, and ferrosteel may be used in connection with temperatures up to and including 450 degrees F.

(2) Hard brass, bronze, and other compositions, of which 95 percent is copper, tin, and zinc, may be used in connection with temperatures up to and including 470 degrees F., but this temperature may be increased to 550 degrees F. when the manufacturer of the valves or fittings stamps them with the temperature they are guaranteed to stand without disintegration. This paragraph will also apply to any composition meeting the above physical requirements and stamped in accordance therewith.

(3) For temperatures exceeding 550 degrees F. no valves or fittings other than steel or of a composition whose tensile strength has been demonstrated to exceed 50,000 pounds per sectional square inch with an elongation of 10 percent in a length of 2 inches shall be allowed. Such valves and fittings shall be stamped as above required.

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P= maximum allowable pressure, in pounds per square inch.

D= diameter, in inches.
T-thickness, in inches.

(d) Cast iron fitting. The minimum thickness of cast iron, semisteel, or ferrosteel fittings shall be determined by the following formula:

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P= maximum allowable pressure, in pounds per square inch.

D= internal diameter of the largest opening contained in the cylindrical part of the casting in inches. (e) Nonferrous slip joints. (1) The wearing surface of the male pipe in all slip joints made after June 30, 1908, for use in steam pipes shall be made of copper or composition, and shall be of sufficient length and so adjusted as to prevent accidental withdrawal from the packing box. When made of composition, same shall be of not less than 95 percent copper, tin, and zinc, possessing a tensile strength of not less than 30,000 pounds to the square inch. It may be used for sizes up to and including 12 inches in diameter, and for all pressures not exceeding 300 pounds per square inch.

(2) The minimum thickness of such fittings shall be determined by the following formula:

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(a)

§ 68.05-10 Valves and fittings. Valves and fittings of 3 inches and under may be connected by screw threads at their intermediate joints in pipe lines.

(b) Each and every valve for marine service shall have the trade-mark of the manufacturer cast or stamped on the chamber. All such valves of 2 inches diameter and over shall be subjected by the manufacturer before shipment to a hydrostatic pressure of three times the working pressure which the manufacturer guarantees them to stand without distorting, and shall also be stamped with such working pressure and also the letters "M. S." which shall plainly indicate that the valve has met the test requirements for marine service.

(c) All valves of over 2 inches diameter, without regard for the service for which they are intended, installed after April 30, 1917, shall have bolted bonnets.

(d) Screwed bonnets on cast-iron valves of any size and for any character of service are positively prohibited.

(e) All pipe fittings of more than 3 inches internal diameter shall be subjected by the manufacturer to a test of three times the pressure to which they will be subjected in service.

§ 68.05-13 Joints and flanged connections (a) Flanges and connections for wrought-iron and homogeneous-steel feed and steam pipe. (1) The terminal and intermediate flanges of all wroughtiron and homogeneous-steel feed and steam pipe over 2 inches in diameter, other than on pipe or coil boilers of steam generators, shall be made of wrought iron, homogeneous steel, malleable iron having a tensile strength of not less than 30,000 pounds per square inch of section, or equivalent material.

(2) All such flanges shall have a depth through the bore of not less than onehalf of the diameter of the pipe to which the flange is attached.

(3) The bore shall increase slightly toward the face of the flange, and the end of the pipe shall be enlarged to fit the bore of the flange and shall be substantially beaded over or outward into a recess in the face of the flange.

(4) Flanges on extra heavy lap-welded steam pipe up to and including 5 inches diameter may be attached with screw threads and the joints in bends may be made with extra heavy malleable-iron elbows or equivalent material.

(5) Feed and steam pipe up to and including 3 inches diameter may be connected at intermediate joints by being screwed into flanges or extra heavy fittings.

(6) Flanges of cast iron, semisteel, or ferrosteel, having a tensile strength of not less than 20,000 pounds per square inch of section, may be employed in connecting extra heavy lap-welded pipe by screw threads. Such flanges shall be extra heavy and have a depth through the bore of not less than the United States standard length of thread for the pipe to which the flange is attached plus depth of counterbore. The thickness of the flange, excluding hub, shall be not less than three-tenths of the diameter of the pipe plus 0.25 of an inch. The pipe shall fit snugly in the counterbore, which shall be not less than one-fourth the diameter of the pipe in depth.

(7) Flanges of wrought iron or steel grooved in the bore to a depth equal to the thickness of the material in the pipe shall be allowed for use on all steam and feed pipe when the end of the pipe has

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