US1992960A - Conduit junction - Google Patents

Description

March 5, 1935. B. H. MILLER ET AL CONDUIT JUNCTION Filed June 25, 1932 4 Sheets-Sheet 1 INYENTORS Ben amin EMU/er BY James E. fiainer March 5, 1935. B. H. MILLER El AL CONDUIT JUNCTION Filed June 25, 1932 4 Sheets-Sheet 2 INVENTORS Ben jamin H. M 1712! BY James 1?. Trainer R- V ATTORNEY March 5, 1935. B. H. MILLER ET AL CONDUIT JUNCTION Filed June 25, 1932 4 Sheets-Sheet 3 Fig 10 INVENTOR Ben amzn HJVIIIIer BY Jalnes E. Trainer P, 1 ATTORNEY March 5, 1935. B. H. MILLER El AL CONDUIT JUNCTION Filed June 25, 1932 4 Sheets-Sheet 4 r e r m Mmw Hnwm .mE .R mmih m a A m wm 2m B Patented Mar. 5, 1935 UNITED STATES CONDUIT JUNCTION Benjamin H. Miller, Wadsworth, and James E.

Trainer, Fairlawn, Ohio, assignors to The Babcock & Wilcox Company, corporation of New Jersey Bayonne,=N, J., a

Application June 25, 1932, Serial No. 619,212

Claims. (01. 285106) This invention relates to junctions between pressure vessels or conduits, and more particularly to the reinforcement of such junctions.

The invention has special reference to junc- 5 tions of walls of generally curvilinear cross section and is especially useful when the conduits are cylindrical and of circular cross section. They may be of the same size, or one may be smaller than the other, as, for instance, where 0 a small diameter conduit joins a larger one, or

where an outlet is taken off from a heavy pressure vessel such as a boiler drum.

The invention is also applicable to junctions between vacuum vessels or conduits, as for example surface condensers and their inlet steam connections.

It is also applicable to pipe joints in general and particularly to pipes of very large diameter.

The problem presented by junctures of the character 'above mentioned arises from the cutting out of a large section of metal of the wall of the conduit where the branch is to enter. The hole interrupts the continuity of the conduit wall circumferentially, leaving, in effect, an open ringbetween two planes at right angles to its axis and tangent to the hole and pressures from within tend to open the same while pressures acting on the outside tend to close it. There is nothing to resist these loads except the adjacent metal of the uninterrupted rings on both sides and this adjacent metal is thus over stressed. To avoid such excess stress'in metal beyond the planes tangent to the hole and to support the open ring.

" between them is the problem.

It has been the practice in the past to meet the above problem by thickening the edges of the metal around the hole by applying a band or ring of metal therearound, welded, riveted or otherwise held in place partly on the metal section 40 between the two tangent planes andpartly on the adjacent metal beyond them. Such reinforcing rings which are, in effect, circles bent out of a plane to conform to a cylindrical surface are not well adapted to join the ends of the cylindrical bands of metal separated by the hole without overstressing adjacent metal of the uninterrupted cylinder. In fact, it is quite possible under certain conditions that the effect of such reinforcing rings may be more prejudicial than help- 50 ful and that they may weaken the structure by introducing new localized stresses beyond the capacity of the metal to resist Consequently, this present invention has, as one of its objects, the application of an entirely new discovery with respect to neutralizing the Specifically the invention contemplates the ap- 4 plication to a conduit, pipe, pressure or vacuum drum, of a new kind of structural member which we designate an arched link member passing. around the cut-out portion and joining the ends of the circumferential sections of the conduit pipe, which if continuous would intersect the area removed for the purpose of making the connection, the arched link replacing the cut-out metal and assuming the load that it would carry without overstressing adjacent metal beyond the hole. This arched link is attached to the walls of the conduit in a manner appropriate to its purpose.

In particular the arched link member invention may take the form of a closed elongated link with opposite ends V-shaped, the widest portion passing around the cut-out for the juncture, the whole link being bent to arch shape to conform to the cylindrical surface, each V end secured to an end of the circumferential strip interrupted by .the hole, by forming it integrally with the conduit, or by'welding or otherwise. The arched link member is further characterized by increasing cross section of metal from ends to middle I and also may be further characterized by a junction web across the space between the legs of both Vs to further resist any sidewise movement of the sides of the link with reference to each other,

J the web also conforming to the cylindrical surface.

In a preferred form which the invention may take, the arched link member is comprised of a group of separate structural elements or layers of plate, each of which is of a thickness more or less equal to that of the metal of the shell to which it is attached, and each separately attached.

This is especially advantageous in attachment of the arch link to the shell by welding as it avoids the danger of burning the thinner of two pieces of metal such as might occur if pieces of materially different thickness were to be used.

This arched link member when attached, joins the two ends of the circumferential strip interrupted by the hole and opposes the force acting at one end to that acting at the other, transmitting such balancing loads around the hole and circumferentially around the shell in which the hole has been made. When a side connection is to be made to the hole, it may be attached directly inside of the arched link without danger of overstressing, and the arched link may be attached to said side connection or according to local conditions.

Fig. 1 is a plan view of a portion of a conduit drum or shell to which the invention is applied;

Fig. 2 is a sectional view on the line 22 of Fig. 1;

Fig. 3 is a sectional view on the line 33 of Fig. 1;

Fig. 4 is a side elevation of the assembly shown in Figs. 1, 2 and 3;

Fig. 5 is a plan view of another form which one element of the invention may take in practice;

'Fig. 6 is a sectional view on the line 6-6 of Fig. 5;

Fig. 7 is a sectional view on the line 77 of Fig. 5;

Fig. 8 is a sectional view similar to Fig. 5 but showing the smaller conduit intersecting the larger at an acute angle;

Fig. 9 is a side elevation of a conduit junction with an offset branch;

Fig. 10 is a sectional view on the line 1010 of Fig. 9;

Fig. 11 is a side elevation of a conduit junction in which the branch is of the same size as the main conduit;

Fig. 12 is a bottom plan view of the form shown in Fig. 11; and I Fig. 13 is.a view similar to Fig. 2 but with a web plate in the arched member.

Fig. 14 is aside elevation of another form of applicants invention.

Fig. 15 is a sectional view on the line 1515 of Fig. 14.

In detail:

The invention as shown in Figs. 1 to 3 inclusive comprises the conduit 1, curvilinear in cross section, and shown .as cylindrical and from which metal has been cut away to provide an opening 2 shown circular, and to the edge of which is secured a branch connection 3 shown cylindrical and of material of the same thickness in cross section as the conduit 1, with edges welded as indicated at 4. There is thus left, by the metal cut out at 2, an unsupported ring of the conduit lying between two 'planes tangent to the hole and indicated by the lines X-X and Y-Y. This ring has no resistance to deformation by pressure from within the conduit, due to this interruption, except as contributed by the edges of the conduit portion where no metal has been cut away.

In order to restore, or to increase the original strength of the conduit with mosteconomical use of metal, the present invention provides an arched link with V-shaped ends, 6, 7, 8 and 9, the wide portion between the two V-shape ends passing around the opening 2, and which may, or may not have a web plate 34, as shown in Fig. 13, between the legs of the V, the whole arch link being adequate to at least completely restore the original strength of the structure as a whole when the opposite V ends of the arch link are welded in place as shown at 12 and 13.

As shown, the arch link at its widest portion is brought into contact with the sides of the branch 3 and may be welded there as shown, but this is not necessary to the invention, according to which the arch-link may act efiectively without any connection to the branch 3 or even without touching it.

In the modification illustrated in Figs. 5, 6 and 7, the arch link is of laminar construction, being formed by strips of metal 16, 17 and 18, preferably rolled plate, set normal to the surface of the conduit 19 and each separately welded as at 20, 21 and 22, respectively. By the use of strips, that are of the same thickness as the material of which the conduit 19 is formed, there is least danger of burning either piece by welding as the same welding heat is required for both. The inner strips 16 on each side are welded together as at 23, to complete the link, whereby the total arched link structure produces the same reinforcing factor as was described in connection with the form of the invention illustrated in Figs. 1, 2 and 3. i The outer strips may be successively shorter or longer and the width of each strip may increase from end to middle as shown for most economical use of metal, but in the.

practice of the invention this feature while desirable, is not necessary. Also, the inner strip, which is shown touching the branch 14, may be wholly out of contact with it.

In the modification shown in Fig. 8 the hole 25 has welded to the edge thereof the branch 26, the axis of which makes an angle other than a right angle with the axis of the shell, and the arch link is formed around the hole by strips of metal as in Figs. 5 and 6, where the intersection is a right angled one, each strip being welded as indicated at 30, 31, 32 and 33.

In the form of the invention illustrated in Figs. 9 and 10 the construction is the same as that described in connection with Figs. 1, 2 and 3 and consequently the same reference characters have been used. However, these .views disclose an arrangement in which the opening or cut-out 2 is offset with respect to the longitudinal axis of the conduit 1, and the arch member formed by the diagonals 6, 7, 8 and 9 overlies the material around the opening and strengthens the open ring portion in the same manner as described in connection with Figs. 1, 2 and 3.

In Figs. Hand 12 there is illustrated one type of junction in which the outlet may be of the same size as the main conduit and which thus takes away a larger amount of metal than in the other forms illustrated. Under such conditions it is advisable to extend the arch member substantially around the main conduit. In Figs. 11 and 12 the conduit 35 is provided with a cut-out on the line 36 to receive a branch 37 of the same diameter as the conduit 35. The arch member is comprised of two elements 38 and 39 which may be spaced from the sides of the branch outlet 37, as shown, and extend around the conduit 35 and meet in the weld 40 at the bottom in a line parallel with the axis of the conduit 35, the shape of the elements 38 and 39 providing the same meeting Vs as referred to in connection with the other forms.

Fig. 13 is shown as illustrative of further reinforcement by welding the web 30 within the confines of thearched link member of any of the types herein disclosed.

In Figs. 14 and 15 we have disclosed another method of reinforcing the junction between two conduits, and while this method is applicable to all sizes of junctions, it is especially desirable on junctions where the branch is the same size as the main.

In such construction as is shown in Fig. 14 the main 35 having a branch 41, of the same diameter as the main 35, has strips 42, 43, 44, 45 and 46 on the one side of the branch 41, and similar strips 42', 43', 44', 45' and 46 on the other side, and which are welded in place edgewise and splayed from each other at the ends as shown, with the exception of the two innermost strips on each side, namely strips 45, 45', which are joined at their ends as at 4'7, and strips 46, 46' which are crossed, as shown, and welded at 48. Intermediate the adjacent strips are placed supports 49 and 50 on each side respectively, and which are not only welded to the adjacent strips but may be welded to the body of the conduit 35 as are also the strips 42 to 46 and 42' to 46'.

It will be noted that with this construction, as in fact with all of these constructions, the interrupted stress from the rings cut by the hole where the branch joins the main conduit is carried by the reinforcement on either side of the hole in pure tension, due to the fact that the half of the arch link or similar construction which forms a triangle or the like in connection with the shell plate, or further necessary enforcement,

forms a beam which takes the distributed load of the interrupted rings and carries it to either side.

In the supported reinforce or splayed type of reinforcing member as disclosed in Figs. 14 and 15, it is to be noted that we do not confine ourselves in this invention to keeping the reinforcing bars close together for their full length, but that they may be separated at their ends so that each bar welded in place will gather up its share of the hoop stress.

The foregoing constructions have particular application in large conduits such as are being used in the new Hoover Dam, where the main penstock may be 30 feet in diameter with branches of feet diameter or larger.

In all forms of the invention herein illustrated it is to be noted that the force or load resulting from pressure difference between inside and outside of the conduit is resisted by the arch link where, by the cut-out or hole, there is none of the original metal, and the arch link does this withou overstressing adjacent metal.

With regard to practicing the invention, the forms illustrated do not represent all methods by which the invention may be practiced, but are sufiicient to comply with the statutes requiring a full disclosure of the invention. It is to be understood that the reinforcing structure or arch link, may be a casting, a forging, may be made up of laminations or welded parts, or may be formed in the conduit itself without in any way departing from the letter of the invention. It.

out and having unequal axes, its major axis being disposed transversely of the longitudinal axis of the conduit, said link comprising laminations each attached to the conduit to form the link in its entirety.

2. In combination, a conduit curvilinear in cross-section and cut out to receive a branch, a branch connection contiguous with said out out, and an arched link member embracing said out out and having unequal axes, its major axis being disposed. transversely of the longitudinal axis of the conduit, said link comprising laminations each of a thickness of the conduit material and individually welded to the conduit, the said laminations being joined to form the link in its entirety.

3. A tubular conduit having a branch outlet, the juncture of which interrupts the circumferential elements of the conduit thereby diminishing hoop strength, and links applied to the conduit around the juncture with the longitudinal length of the conduit in contact-with said links decreasing circumferentially from the center line of said juncture to restore hoop strength.

4. A tubular conduit having a branch outlet the juncture of which interrupts the circumferential elements of the conduit thereby diminishing hoop strength, and links circumscribing the juncture and directed at intersecting angles and secured to the conduit to restore hoop strength.

5. A tubular conduit having a branch outlet the juncture of which interrupts the circumferential elements of the conduit thereby diminishing hoop strength, and links circumscribing the juncture in a substantially diamond shape with the major axis disposed circumferentially of the conduit and secured thereto to restore hoop strength.

BENJAMIN H. MILLER. JAMES E. TRAINER.

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