US2207813A - Fuse construction - Google Patents

Description

July 16, 1940. G. F. McMAHoN r-:r AL

FUSE CONSTRUCTION Filed Jan. 30. 1939 s sheets-sheet 1 July 16, 1940. G. F. McMAHoN Er A1. 2,207,813

FUSE CONSTRUCTION Filed Jan. 30, 1939 3 Sheets-Sheet 2 'y-5 ,35 32 L7M/1 July 16, 1940 G. F. McMAHoN Er AL 2,207,813

FUSE CONSTRUCTION Filed Jan. 30, 1939 3 Sheets-Sheet 3 Patented July 16, 1940 UNITED STATES PATENT OFFICE FUSE CONSTRUCTION George F. McMahon, Evanston, Ill.,

Conrad, Delaware and Allan Ramsey, to Schweitzer &

Application January 30, 1939, Serial No. 253,508

1s v claims'.

Our invention relates generally to improvements fin fuse construction, and it is particularly related to improvements in liquid fuse tube construction wherein external metal terminals are sealed to glass tubes or housings. The glass most generally used is of the boro-silicate low expansion heat resisting type.

The general construction of liquid fuses comprises a length of glass tubing to the ends of which annular metal terminals are sealed. Arc extinguishing liquid is contained in the glass tube together with conducting means including a predetermined fusible portion which interconnects the terminals. On blowing of the fusible portion an arc is formed between terminals of the conducting means, and one of these arcing terminals is adapted to be drawn beneath the surface of the arc entinguishing liquid which evolves an arc extinguishing medium that assists in extinguishing the arc.

These liquid fuses are commonly used outdoors on high potential transmission lines. Being so exposed, they are subject to wide changes in temperature. For example, in the United States the outdoor temperature during the year may vary' from 120 F. in the summer to below zero in the winter, thus easily giving a range of temperature change of 120 F. or more.

The temperature to which the external metal terminal ferrules or caps are subjected due to heat generated as a result of the I R drop through the fuse constitutes an important factor to which consideration should be given. When the fuse .problem hasbeen more is operated for relatively long periods near its `ratedf capacity this temperature may be fairly high under certain conditions.

In' sealing an annular terminal ferrule or cap I to the glass tubing or housing, the annular space between the glass tube and the inside of the terminal is iilledvwith a sealing alloy. "I'he problem of providing a' satisfactory seal between the annular terminals and the glass tube, which will be mechanically strong'and remainunchanged overa long period of time and will withstand a large .range of temperature change'and at the same time leave the glass tube unimpaired has required considerable research to solve. The

sizes of liquid fuses and the smaller sizes with terminal ferrules or caps of relatively great thickness. In these larger sizes of vfuses the diameter of the glassv tube varies from one and one-half inches to threeinches, and 'the ferrule wall thickness Afor a' given size variesr considerably since certain portions are round and .other portions are slabbed o".

'I'he sealing of round ferrules or caps with milled or slabbed oif. ilat portions on the exterior has always been a serious problem because of the differential expansion of the metal termidifilcult in the largery (Cl. 20o-113) nais and the glass tube,'since the sealing alloy must not only seal the annular space provided therebetween but must also act as a cushion to absorb some of the force due to this differential expansion. Otherwise, the glass tube may be cracked or broken and the liquid may leak out. The sealing alloy must not have too low a melting point or solidication point or be too soft and the wall thickness must not be too great for otherwise leakage will arise. Accordingly, it has been the practice to balance these factors, i. e., thickness, temperature characteristics and hardness, so that the best possible seal could be made under the circumstances. The seal thus provided has been quite satisfactory but there still remains considerable room for improvement.

` Of several sealing alloys available, there is one group which is particularly desirable because of its Wide range in melting point and solidification temperature characteristics. In general, the alloys of the tin, lead and cadmium system are quite useful, although some alloys containing bismuth have given good results. One alloy in particular has been used with excellent success in connection With liquid fuses of smaller size, but up to the present invention it was too hard and the solidilcation temperature too high to be used in connection with the larger sizes of fuses.

An important object of our invention is to provide an improved seal between heavy glass tubing and heavy metal terminals.

Another object of our invention is to provide liquid fuses in the larger sizes in which an alloy of superior qualities may be used -for sealing the terminal ferrules to the glass tubing of the fuse than has been possible heretofore.

Another object of our invention is to provide liquid fuses in the larger sizes `which are substantiallyY free from breakage. and leakage resulting at the Vsealsvbetween the terminals and the glass tube or housing of the fuses.

` Still another object of our invention is to provide liquid fuses which can satisfactorily operate at higher current values than has heretofore been possible.

A further object of our invention is to accommodate the diierential expansion that occurs when a relatively high melting point alloy is employed for sealing a metal sleeve to a glass tube. v

-A still further object of our invention is to equalize the stresses incident to the sealing of a metal sleeve having a non-uniform wall thickness to aglass tube. y

Other objects of our inventionwill, in part, be obvious and in part appear hereinafter.

According to our present invention we have provided a seal between heavy glass'tubing and an annular metallic terminal `ferrule or cap therevlili for in which a sealing alloy of the above described desirable type may be used. This seal has proved to be far superior in respect to reliability and freedom from breakage than any seal provided heretofore. By a metal terminal, we refer to a ring or band of metal that may be closed at one end and open at the other or open at both ends. When the terminal is closed at one end and open at the other, it is referred to as a base or cap. When it is open at both ends it is referred to as a ferrule. In liquid fuses of larger size the terminals employed are substantially cylindrical with flat surfaces machined or .slabbed o on opposite sides thereof. These at surfaces are provided to more readily permit clamping into fuse clip terminals and increased contact area. By having these flat surfaces machined on opposite sides of a terminal, its thickness is not uniform. Therefore, since the mass of metal is not uniform around the circumference, the force due to differential expansion between the metal terminal and the glass tubing, will be unequally exerted on the glass tube. We have found by slotting the terminal ferrules and caps in a certain manner that the above-mentioned desirable type of sealing alloy can be used and that this inequality of contracting stress or force is greatly reduced. The maximum wall thicknesses of the slotted ferrules and caps used are many times the thicknesses of the alloy forming the seal.

For a more complete understanding of the nature and scope of our invention, reference may behad to the following detail description, taken in connection with the accompanying drawings, in which:

Figure 1 is a view, in front elevation, showing a liquid fuse tube;

line 2-2 of Figure 1;

Figure 3 is a view, in side elevation, of the lower terminal or base of Figure 1, part of the ferrule being broken away to show the inanner in which the glass tube is sealed into the ferrule;

Figure 4 is a view, in side elevation, of the upper terminal or ferrule of Figure 1, part of the ferrule being broken away to more clearly -ihow the details of construction;

Figure 5 is a view, in side elevation, of a modied form of liquid fuse tube in which two sections of a glass tube are joined by a ferrule;

Figure 6 is a longitudinal sectional view at an enlarged scale of the middle ferrule of Figure 5 taken along the line 6 6;

Figure 7 is a longitudinal sectional view of a combination terminal in which a ferrule and a condenser are combined; f

Figure 8 is a view, partly in elevation and partly in section, of a liquid fuse tube provided with round rather than slabbed off terminals;

Figure 9 is a bottom plan view of the construction shown in Figure 8;

Figure 10 is a view, 'partly in elevation and partly in section, showing a flanged joint conor pipes; and

Figure 11 is a detail sectional view taken along the line II-II of Figure 10. Referring now to Figure 1 of the drawings, the reference character IIIv designates, generally, a liquid fus'e housing comprising a glass tube or housing II, a lower terminal or base I2, and an upper terminal or ferrule I3. A cover or vent cap III -is provided for closing off the top of the ferrule I3 and it may be blown off on generation of sumcient pressure in the housing Il.

Figure 2 is a sectional view taken along the struction for interconnecting abutting glass tubes In order to permit the use of a higher melting point alloy and at the same time accommodate the resulting stresses due to the differential expansion between' the terminals and the glass housing II, longitudinal slots or grooves l5 and I6 are provided in the base I2 and the upper ferrule I3 respectively. The opposite sides of the base I2 and ferrule I3 are slabbed off to provide parallel flat surfaces I1 and I8, respectively. The alloy for sealing the lower base I2 and the ferrule I3 to the glass tube II is shown protruding at I9 and 20, respectively.

In order that the character of the seal between the glass tube II and the terminals I2 and I3 will be more readily understood, reference will now be had toyFigures 2 and 3 of the drawings. Although these figures relate particularly to the base I2, whatever is said about it applies equally well to the sealing of the ferrule I3. It will be observed that the lower end of the glass tube II fits into a machined out portion of the base I2 and that its outer lower edge rests against a cork gasket 22 conforming to the shape of the bevelled surface 23. The cork gasket 22 prevents chipping,

of the end of the glass tube II. The sealing alloy I9 lls the continuous uniform annular space between the glass tube II a`nd the inside of the base I2 and, in the liquid state, is prevented from flowing further into the base I2 by the closing off of this space by the cork gasket 22. The sealing alloy I9 is surrounded by a continuous unbroken flange of metal provided by the base I2. It will be noted that, by having the flat 'sides I1, Figure 1on the base I2, its thickness is thereby rendered nonuniform. In order to reduce the distorting effect of this nonuniform thickness while the metal of the base I2 and its alloy seal I9 are cooling, we have provided the slots I5. After the slots I5 have been cut in the thicker portions of the walls of the base I2, it can be considered that it now consists of a relatively thin ring of generally uniform thickness to which are attached, along portions of its outer periphery,

a number of heavyspaced lugs. With this slottedconstruction the severe distortion produced by a ring of non-uniform thickness is reduced and the stresses more evenly distributed. It will be noted that, since the slots I5 do not extend all the way through the base I2, a continuous unbro'ken band or ring of metal remains to retain the sealing alloy I9. The thickness of this unbroken band or. ring is substantially the same as the minimum thickness of the atportions I1.

By thus providing grooves or slots in the terminals I2 and I3, it has been possible to use a sealing alloy in the largensizes of fuses which has characteristics lwhich are superior to the alloys previously used. In particular, al sealing alloy of substantially the following composition has been found to have excellent lcharacteristics for this purpose:

Per cent Lead --.t 25 Tin i 50 Cadmium 25 This alloy has a melting point of 154 C., a solidii-lcation point of 144 C. and a Brinell hardness of 23.6 when tested at a 500 kilogram load on a' 10 m. m. ball for five seconds. We have found that the maximum thickness of the side walls of the terminals I2 and I3 can be of the order of 2 to '7 times the thickness 0f the alloy between them and the glass tube I I when the slotted constructiony is used and that this relatively hard shortly start to melt and alloy can be used in such a construction without likelihood of cracking or breaking the glass.

Heretofore, it has not been possible to use such a sealing alloy in the larger sizes of liquid fuses because Brinell hardness were too high. Consequently, sealing alloys of lower temperature characteristics and hardness were used. These other sealing alloys had lower melting points andA fuses employing them were accordingly limited to the temperature at which theycould safely operate.

Moreover, it has been found that a sealing alloy of the above composition not only melts at a higher temperature than certain other sealing alloys, but also that the time taken for it to melty is substantially greater. Thus, when the usual type of soft sealing alloys is used, as soon as they reach their solidiflcation temperature, they very allow the fuse liquid to leak out. However, in the preferred type of sealing alloy 'mentioned above, a substantial time must elapse before the alloy will soften after it has reached its solidication point. Accordingly, the possibility of leakage is further reduced.

When this preferred type of sealing alloy, or its equivalent, was used in the larger sizes of fuses with unslotted ferrules, breakage of the glass tubing frequently occurred. 'Ihe alloy solidified at too high a temperature and was too hard to accommodate the forces set up duel to differential expansion between the metal terminal ferrules or caps and the glass tubing. However, by slotting or grooving the terminals in the manner described we have been able to use this preferred type alloy without likelihood of breaking the glass tubing and accordingly are able to obtain full advantage of its high melting point and long time melting characteristics.

In general it may be stated that it is preferable to employ an alloy which has a solidicatlon temperature of 115 C. or more and a Brinell hardness of 19.6 or more, although an alloy having a solidication temperature of 100 C. and a Brinell hardness of 18 or more may be used with the slotted ferrule construction.

'I'he ferrule I3, shown in Figure 4, is provided with a threaded section 26 into which an arcing tube support washer may be screwed. The vent cap I4, Figure 1, is cemented onto the outer surface of the recessedupper end portion 21. The upper end of the glass tube II is sealed into the ferrule I3 in the same manner that the base I2 is sealed to the lower end.

In some types of liquid fuses, such as the repeating fuse construction shown in.Iriplett Patent No, 2,087,744, it is necessary that sections of glass tubing be joined and that threeterminals be provided. Referring now to Figure 5v of the drawings, it will be observed that such a liquid fuse is designated generally at 30. The fuse 30 comprises a lower terminal 3l, which constitutes a switch terminal,. an upper terminal 32 and an intermediate terminal 33,

latter two constituting the Afuse terminals with" the intermediate terminalv 33 also serving as a v' switch terminal. The intermediate terminal 33 joins sections 34 and 35 of glass tubing. 'I'he lower and upper terminals 3l and 32 are essentially the same as terminals I2 and I3 described hereinbefore. The sides of the terminals 3|, 32 and 33 are slabbed off, as clamping in the circuit terminals or fuse clips.

The construction of the intermediate ferrule 33 is more clearly shown in Figure 6 of the drawings. It will be observed that it comprises a ymain its temperature characteristics andv ,f alloy 4 I,

tubular' body member, the lower end 36 of which is reduced in diameter and provided with an annular groove 31 for receiving the upper end of the section 34 of glass tubing. A lling 38 of sealing alloy serves to seal the section 34 in place. The upper end 39 of the tubular body member is provided with a series of longitudinally extending grooves 40 in order to avoid the stresses incident to the differential expansion of the terminal 33 and the section 35 of glass tubing which is securedvtherein by the sealing as previously ldescribed. Preferably a cork gasket 42 is provided underneath the lower end of the section 35 of glass tubing for 'the' purposes set forth hereinbefore.

In Figure 7 of the drawings a combination terminal is shown generallyat 45. This combination terminal 45 may be employed on the glass tube II, Figure 1, in place of the terminal I3. The terminal 45 comprises a condenser section 46 and' a ferrule section 41. The condenser is employed for cooling and. condensing the arc products resultingfrom the blowing of the fusible element of the fuse on the occurrence of an overload in certain fuse installations.

The combination terminal 45 is preferably formed from tubular brass stock with the condenser section 46 machined out to form the condenser chamber. 'I'he ferrule section I1 is provided with a plurality of longitudinally extending grooves 48 to permit the melting point sealing aloy, as set forth hereinbefore. It will be noted that the opposite sides of the lowermost portion of the ferrule section 41 are slabbed oi as shown at 40 to facilitate clamping in the clip terminals and that the grooves 48 which would otherwise extend the full length of the ferrule section 41 are terminated at the upper edges of the slabbed off portions 49.

The upper end of the glass tube II is inserted in the machined out portion 50 of the ferrule section 41 and rests against a cork gasket 5I which conforms to the sha-pe of the bevelled surface 52. The filling 53 of the relatively high melting point alloy is poured into the space between the glass tube II and the inner surface of the machined out portion 50, ani, on solidifying, provides a sealed joint therebetween.

In all the above described modifications of terminals it has been possible by longitudinally slotting them to use a sealing alloy of greater hardness and higher melting point than has been pcssibe heretofore. In actual tests that have been made, we have found that liquid fuses embodying our4 invention, i. e., longitudinally grooved or slotted terminals in combination with a relatively high melting point sealing alloy, have been able to operate at temperatures ranging from 25 C. to 35 C. higher than has' been possibe with prior terminal constructions in which a `relatively lower melting point sealing alloy was required without leakage occurring at the alloy seals.

In Figures 8.and 9 of the drawings a fuse tube construction is shown, generally at yIii), in which the present invention is embodied. There are certain appications of fuses where it is desirable to replace a higher capacity fuse with a lower capacity fuse. It is, of course, undesirable to change the fuse clips thatare employed. It is often the case that the terminals of the fuse of smaller capacity are of such dimensions that they Will not fit in the fuse clips provided for the fuse of higher use of a higher4 capacity. This problem can be ness of the terminals 6l and A provided between Difficulty has been expenenced in providing an adequate seal between these extra large terminals employed on the glass tubes of the smaller capacity fuses. When the section of the metal forming the terminals is increased, there is of course insuicient flexibility from an expansion and contraction standpoint to permit the use of relatively hard alloys to provide the sealing connection.

This difficulty ma be overcome by employing the terminals 6| and 6|', as shown in Figure 8, at the ends of a fuse tube 62. The terminals 6I and 6|' are spaced from the ends of the tube '62 and the space therebetween is filled with. an alloy 63.` The alloy 63 is preferably of thetype described hereinbefore having a melting point of 154 C., a solidiiication point of 144 C. and a Brinell hardness of 23.6. Other alloys having a Brinell hardness of 18 or more may also be used.

It will be observed that the over-all wall thick- 6I is relatively great. By providing the longitudinally ranging slots 65 inthe external surface of the `terminals 6I and 6I' it is possible to provide a comparatively flexiblev terminal construction having a sufficient range of expansion and contraction to accommodate the relatively hard alloy 63 without fracturing the glass tube 62.

As illustrated in Figures 10 and l1 of the drawings, it is possible to employ the present invention for interconnecting a pair of glass sleeves 10 and 1I forming a part of a pipe line such as may be used in certain applications where it is undesirable to employ metal for the pipe. For the purpose of joining the glass sleeves or pipes 10 and 1| at the abutting end of each a coupling member, is secured. Each coupling member 12 comprises a ring-like section 13 that is spaced from the outer surface of the pipe or sleeve 10 or 1 I. This space is filled with an alloy 14 having the characteristics previously described. Preferably the alloy 14 has a melting point of 154 C., a solidification point of 144 C. yand a Brinell hardness of 23.6. Other alloys may be employed. However, it is preferable that they have a solidiiication temperature of 100 C. or more, and a Brinell hardness of l8,or more.

In order to relieve expansion and contraction strains the ring-like portion 13 is provided with a plurality of longitudinally ranging grooves 15 that extend inwardly but not through this portion.

With a view to clamping the coupling members 12 together, they are provided with radialy extending flanges 16 having apertures 11 therein through which suitable clamp bolts 18 may be inserted. It will be obvious that any other suitable clamp means may the coupling member 12 in juxtaposed relation.

A gasket 19 formed of uitable material may be the juxtaposed ends of the glass pipes 10 and 1| to provide a'fluid tight seal.

Since certain further changes may be made in the foregoing constructions and different embodiments of the inventionmay be made without departing from the spirit and scope thereof. it is intended that all matters shown in the accompanying drawings or set forth in the foregoing description shall be interpreted as illustrative and not in a limiting sense.

shown generally at 12,`

be employed for securingv We claim as our invention:

l. In combination, a frangible sleeve, a metallic ring surrounding said sleevel and spaced therefrom, and an alloy in the space between said sleeve and ring providing a sealed connection therebetween, said ring being of non-uniform thickness and having a plurality of external longitudinally ranging grooves in the thicker body portion thereof the depth of which is substantially less than the thickness of the portion of the ring in which they are situated.

2. In combination, a frangible sleeve, a metallic ring surrounding said sleeve and spaced therefrom, and an alloy in the space between said sleeve and ring providing a sealed connection therebetween, said ring being of non-uniform thickness and having a plurality of external longitudinally ranging slots extending inwardly but not through the thicker body portion thereof, the remaining thickness between the bottoms of said slots and the inner surfaceA of said ring being substantially the same as that of the thinner portion.

3. In combination, a frangible sleeve, an outer metallic ring having longitudinal grooves in the body portion thereof and being spaced from said sleeve, and a sealing alloy in the space between said sleeve and ring, the melting point of said alloy being substantially lower than that of said ring and the maximum wall thickness of said metallic ring being several times the thickness of the sealing alloy in said space.

4. In combination, a frangible sleeve.' a metallic ring surrounding said sleeve and spaced therefrom, and an alloy in the space between said sleeve and ring having a solidication point of above 100 C. and providing a sealed connection therebetween, said ring having a plurality of external longitudinally ranging grooves in the body portion thereof the depth of which is substantially greater than the remaining thickness of the ring.

, 5. In combination, a frangible sleeve, a metallic ring surrounding said sleeve and spaced therefrom, and an alloy in the space between said sleeve and ring having a solidiilcation point of above 100 C. and a Brinell hardness of 18 or more and providing a sealed connection therebetween', said ring being of non-uniform thickness and having a plurality of external longitudinally ranging slots extending inwardly but not through the thicker body portion thereof, the remaining thickness between the bottoms of said slots and the inner surface of said ring being substantially the e as that of the thinner portion.

6, n combination, a frangible sleeve, a metallic ring surrounding said sleeve and spaced therefrom, and an alloy in the space between said sleeve andring having a solidlcation point from about 115 C. to about 144 C. and providing a sealed connection therebetween, said ring having .a plurality of longitudinally ranging grooves in the body" portion thereof the depth of which 'is substantially greater than the remaining thickness of the ring, the maximum thickness of' said ring being from'about 2 to about 7 times the thickness of said alloy in said space.

7. In combination, a. frangible sleeve, a metallic ring surrounding said sleeve and spaced therefrom, and an alloy in the space between said sleeve and ring having a solldification point above 100 C.- anda Brinell hardness of 18 or more and providing a sealed connection therebetween, said-ring being of non-uniform thickness and Vhaving a plurality of external longitudinally ranging slots 75,

extending inwardlybut not through the thicker body portion thereof, the remaining thickness between the bottoms of said slots and the inner surface of said ring being substantially the same as that of the thinner portion and the maximum thickness of said ring being from about 2 to about '7 times the thickness of said sealing alloy in said space.

8. In a liquid fuseA construction, a frangible sleeve, a ring-like terminal surrounding one end of said sleeve and spaced therefrom, and an alloy in the space between said sleeve and terminal prorality of external longitudinally ranging slots eX- tending inwardly but not through the same, the bottoms of said slots lying substantially along a circle to which the outer surfaces of said slabbed off sides are substantially tangent.

l0. In a liquid fuse construction, a frangible sleeve, a terminal surrounding said sleeve and spaced therefrom, said terminal having a nonuniform wall thickness and having a plurality of external longitudinally ranging grooves in the. thicker body portion thereof, and an alloy in th'e space between said sleeve and terminal for providing a sealed connection therebetween, said alloy having a Brinell hardness above 18.

11. In a liquid fuse construction, a glass sleeve, a ring-like terminal surrounding one end of said sleeve and spaced therefrom, and an alloy in the space between said glass sleeve and said terminal providing a sealed connection therebetween, two

opposite sides of said terminal being slabbed olf and the remaining body portions having a plurality of longitudinally ranging grooves of such depth that a continuous section of metal entirely surrounds said alloy the effective thickness of which with reference to expansion and contraction is substantially uniform and is substantially the same as that of the thinnest portions of said slabbed off sides.

12. In a liquid fuse construction, a pair of glass sleeves disposed end-to-end, a tubular terminal intertting with the adjacent ends of said glass sleeves and spaced externally therefrom, and an alloy iilling the space between said glass sleeves and said terminal providing a sealed connection therebetween, two opposite sides of one end of said terminal being slabbed oif and the remaining body portions having a plurality of longitudinally ranging grooves the depth of which is such as to leave acontinuous metal section in contact with the alloy at said one end.

13. In a liquid fuse construction, a frangible sleeve, a combination terminal having a condenser section at one end and a ferrule section at the other end surrounding one end of said sleeve and spaced therefrom, and an alloy in the space between said sleeve and ferrule section providing a sealed connection therebetween, two opposite sides of said ferrule section being slabbed off and the remaining body portions having a plurality of external longitudinally ranging grooves the depth of which is such as to leave a continuous metal section inl contact with said alloy.

14. In a liquid fuse construction, a frangible sleeve, a combination terminal having a condenser section at one end and a ferrule section at the other end surrounding one end of said sleeve and spaced therefrom, and an alloy in the space between said sleeve and'ferrule section providing a sealed connection therebetween, said ferrule section generally constituting an extension of said ycondenser section and two opposite sides of said ferrule section being slabbed off and the remaining body portions having a plurality of external longitudinally ranging grooves the depth of which is such as to leave a continuous metal section in contact with saidalloy.

15. In combination, a pair of frangible sleeves disposed end-to-end, ring-like metal means surrounding the abutting ends of said sleeves and spaced therefrom, said ring-like metal means having a plurality of external longitudinally ranging grooves extending inwardly but not through the body portion of the same, and an alloy in the space between said sleeves and said ring-like metal means providing a sealed connection therebetween.

16. In combination, a pair of frangible sleeves disposed end-to-end, ring-like metal means surrounding the abutting ends of said sleeves and spaced therefrom, said ring-like metal means having a plurality of external longitudinally rang-- ing grooves extending inwardly but not through the body portion of the same, and an alloy in the space between said sleeves and said ring-like metal means providing a sealed connection therebetween, said alloy having a solidication lpoint from about 115 C. to about 144 C. and a Brinell hardness above 18.

17. In combination, a pair of frangible sleeves disposed end-to-end, a ring-like metal coupling member surrounding and spaced from each of the abutting ends of said sleeves, each coupling member having a plurality of external longitudinally ranging grooves extending inwardly but not through the body portion of the same, an alloy in the spaces between said coupling members and said sleeves providing a sealed connection therebetween, means extending outwardly from each of said coupling members, and clamp means cooperating with said means for holding said sleeves in abutting relation.

18. In combination, a pair of frangible sleeves disposed end-to-end, a ring-like metal coupling member surrounding and spaced from each of the abutting ends of said sleeves, each coupling member having a plurality of external longitudinally ranging grooves extending inwardly but not through the body portion of the same, an alloy in the spaces between said coupling members and .said sleeves providing a sealed connection therebetween, means extending outwardly from each of said coupling members, and clamp means cooper` ating with said means for holding said sleeves in abutting relation, said alloy having a solidification point from about 115 C. to about 144 C, and a Brinell hardness above 18.

GEORGE F. MoMAHON. ALLAN RAMSEY.

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