US2344269A - Expansion joint - Google Patents

Description

' March 14, 1944. F. SACO, JR

EXPANSION JOINT Filed May 29, 1941 2 Sheets-Sheet 1 fizz/I JACO die.

62%; Y I A OR EYS F. SACO, JR

March 14, 1944.

EXP ANSION JOINT Filed May 29, 1941- 2 Sheets-Sheet 2 INVEN TOR fizz/x 540p J15.

ATTOR EYS Patented Mar. 14, 1944 EXPANSION JOINT Felix Saco, Jr., West Hartford, Conn, assignor to The Maxim Silencer Company, Hartford, Conn,

a corporation of Connecticut Application May 29, 1941, Serial No. 395,785

Claims.

This invention relates to expansion joints intended for water heaters, boilers and the like, in which the end headers of a casing are connected together by elements which expand difierently when the device is hot. One object of the invention is to improve the stress distribution in the expansion joint. Another object is to produce an expansion joint which will have an additional utility as a steam collector. A further object is to reduce the amount of welding required. Other objects will appear from the following description and claims. I

Referring to the drawings: I

Figs. 1 to 5 are successive views illustrating the formation of the expansion joint, Fig. 2 being a section on line 22 of Fig. 1;

Fig. 6 is a detail of a modification;

Fig. '7 is a sectional view of a conventional water tube boiler illustrating one form of application of the expansion joint;

Fig. 8 is a fragmentary section showing the invention applied to a waste heat boiler;

Fig. 9 is a section on line 99 of Fig. 8; and

Fig. 10 is a detail of the steam chest box.

The nature of the joint can be understood best from a description of the manner in which it is formed, assuming that the joint is to permit the end header ID of a boiler to have a slight movement relative to the cylindrical shell II. An annular tube I2 is first formed, as by bending a straight tube into annular form and welding its ends together as at IS. The tube is then slit throughout is circumference to form a slot I4 which is displaced to one side of the median plane of the tube. The Width of the slot may be varied, a slot of approximately 45 being shown in Fig. 3 and one of about 90 in Fig. 6. If desired the slot can be made practically 180, although on account of the greater resiliency of the joint produced a slot width in the neighborhood from 45 to 90 is preferred.

The slotted tube is now welded to the outer shell I: along a line I5 (Fig. 4) and is preferably also welded along the opposite surface as shown at It, although the latter weld may in some cases be omitted. It should be observed that the interior weld I6 may be made easily at this time since the header is not yet in place. The header ID is made of such size that it will slip inside the slotted ring as shown in Fig. 5 and it is then welded at H, the header I0 being preferably scarfed as at I8 to permit a weld the full thickness of the metal. In the case of the weld made to the outer shell i I it will in general be unnecessary to scarf either the tube or the shell.

Assuming th header It to be connected to the remote end of the shell I! in some way as by fire tubes I9, or by an interior shell in case the invention is being applied to other than a lire tube boiler, it will be seen that the expansion of the hot tubes I 3 will be greater than that of the shell II which is exposed to the air. The tendency of the header-to move axially with respect to the shell is permitted by the expansion joint described, which is located at the corner between the header and shell. It should be observed that, if the header tends to move, its stress on the slotted tube is substantially directly axial and little bending is caused along the weld line. the major bending action occurring in the tube I2 rather than in the welded areas, which can be made of greater thickness than the surrounding metal but which can be filleted so as to cause no heavy local stress. As the header moves the slotted tube will be caused to open up.

A further feature of the expansion joint described is of particular advantage where it is used on a vertical boiler, or on a waste heat utilizer such as is shown in Figs. 8, 9 and 10, the space within the expansion joint forming an excellent steam chest for the collection of dry steam. In the latter case the outer shell 2| and an intermediate shell 22 form a water jacket 20, the water level line being shown at 33. Within the inner shell 22 is formed a gas passage 23 preferably constructed of angle irons 40 welded in place to each other and to the inner shell to form a plurality of parallel gas conduits as in Fig. 10 of the copending application filed jointly by me and William R. Williamson, Serial N 0. 380,022, on February 21, 1941. The gases escape through a central flue 24 as shown by the arrows in Fig. 8. The end header 25 is welded at 25 to the inner shell 22 and an expansion ring 21 is welded in a manner previously described both to the header and to the outer shell 2|. This joint permits the head 25 to rise or fall with the hot shell 22, which expands much more than the relatively cool outer shell 2I. A discharge pipe 28 fits into the outer shell below the expansion joint and has its end 29 cut away at least partially on its lower surface to permit entrance of steam from below only. The discharge pipe is enclosed by a steam chest box having walls 39 welded in place and extending to header 25 to form a chamber closed except for the gap 3| leading into the expansion ring 27. Steam collects in the expansion ring and passes into the box and out the discharge tube. Condensed moisture is prevented from entering the discharge pipe by the hooded top of th latter,

drops forming within the tube 21 or the steam chest being allowed to drain back to the boiler through a pipe 32 preferably extending underneath the water level with the jacket 20. It will be seen that by th described construction in which the expansion joint is at the corner, a dual function for it is obtained which cannot be present in the usual cases where the expansion joint is formed as a part of the outer shell. Furthermore, less welding is necessary with this construction than with the usual type having the expansion joint between two sections of the outer shell, since the corner between the end header and the outer shell has to be welded in any event and by locating the joint at this point one weld line is omitted.

What I claim is:

1. An expansion joint for vertical boilers comprising a shell, an end header, an annular tube slotted at one side of its median plane and se-' cured at one side to the header and the other side to its shell, a discharge pipe entering the boiler below the tube, and a steam chest enclosing the discharge pipe and communicating with the slotted tube whereby steam may collect within the tube and pass therefrom into the steam chest.

2. An expansion joint for vertical boilers comprising a shell, an end header, an annular tube slotted at one side of its median plane and secured at one side to the header and the other side to its shell, a discharge pipe entering the boiler below the tube, a steam chest enclosing the discharge pipe and communicating with the slotted tube whereby steam may collect within the tube and pass therefrom into the steam chest, and a connection between the steam chest and a point below the water level of the boiler.

3. A boiler, water heater, or the like, comprising a generally cylindrical shell, an end header at substantially right angles thereto, and an annular tube of substantially circular cross section having a slot located asymmetrically with respect to the plane of the annular tube and being secured at one side of the slot to the shell and at the other side of the slot to the header.

4. An expansion joint for boilers and the like having a generally cylindrical shell and an end header at substantially right angles thereto, comprising a toroidal tube of substantially circular cross section and provided with an asymmetrical slot, one edge of which is aligned with the shell and the other edge of which is aligned with the header, said tube being welded to the shell at one side of the slot and to the header at the other side of the slot;

5. An expansion joint for boilers and the like having a generally cylindrical shell and an end header at substantially right angles thereto and of a diameter less than that of the interior of the shell, comprising a toroidal tube of substantially circular cross section and provided with an asymmetrical slot extending substantially from the inner circumference to about half way up one side of the torus, said tube having the first named boundary of the tube welded to the header and. the second named boundary welded to the shell.

FELIX SACO, JR.

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