US1984242A - Conduit junction - Google Patents

Description

Dec. 11, 1934. J. E. TRAINER ET AL CONDUIT JUNCTI ON Filed June 25. 1932 2 Sheets-Sheet 1 ay/22w H. w M

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CONDUI'P JUNCTION Filed June 25, 1932 2 Sheets-Sheet 2 Fi f BY James E Tifliner ATTORNEY Patented Dec. 11, 1934 UNITED STATES 1,9s4,2;42' I CONDUIT JUNCTION James E. Trainer, Fairlawn, and Benjamin H.

Miller, Wadsworth, Ohio, assignors to The Babcock & Wilcox Company, Bayonne, N. J., a corporation of New Jersey Application June 25, 1932, Serial No. 619,213. 3 Claims. (01. 137-75) wall thereof in tension, orif the conduit is under a negative pressure the wall material is under compression, thus, where junctions are formed and cylinders intersect each other at a small angle between their axes there is an interruption or discontinuity of the cylindrical walls with the result that a structure is formed which inherently tends to destroy itself regardless of whether the same is under a pressure or vacuum.

The customary manner of meeting this problem in the past has been to form the walls with a sufficient thickness of material to resist this .tendency toward destruction, but in present competitive markets this procedure becomes impracticable in view of both cost and weight. I The present invention contemplates a structure of the aforesaid character in which the requisite strength is secured without increase of wall thickness over that thickness which would afford an adequate factor of safety provided the intersection was not present.

The invention is more particularly stated by saying that where a junction occurs between two conduits which intersect each other at a small angle between their axes, this invention comprehends the location of a stay plate joining one pair of intersecting edges with the opposite pair and lying substantially in the plane of the intersection of the two conduits.

An additional feature resides in locating and shaping of the stay plate so that, in unequally branched or non-symmetrically branched conduits, the bulk of the material, or an additional amount of material, is utilized to counteract the effect of unequal forces due to flow, in addition to usual tension, and afford the requisite supporting effect necessary in these types of conduit junctions. I

In large size conduits such, for instance, as those proposed for the Hoover Dam where the main conduit is thirty feet in diameter with branches fifteen feet in diameter, the material used may be steel plate, and conservation of metal both for the sake of economy and minimum weight becomes an important factor, as a consequence of which the stay plate construction herein set forth'is of particular importance inasmuch as the walls of the junction need not be of heavier gauge than if they were cylindrical like the main conduit portions; and this involves another'feature of the invention in present-day practice, which is to weld the joints, and where thicker plates are to be welded to thinner plates the heat required to raise the metal of the thicker portion to welding heat may be so great as to burn away portions of the thinner plate and result in spoilage or a physically deficient weld, so that the present invention, which provides welding edges havingthe same relative thickness, thereby reduces, in a 1 large measure, the hazards of welding.

With the above, as an outline of theproblem which the invention solves, and of some of the objects attained, we shall now describe the in vention in such; detail as is required by statute and in connection with the accompanying drawings, in which- Fig. l is a central transverse sectional View of a conduitjunction embodying the principles of the present invention and in the plane of the 29 line 1-1 of Fig. 2; F

Fig. '2 is a viewsimilar to Fig. 1 in the plane of the line 2- 2 of Fig. 1;

Fig. 3 is a plan'view ofthe stay plate prior to forming of the edgesj Fig. 4 is a sectional view on'the line 4-4 of Fig. 2;

Fig. 5 is a sectional view on the line 5-5 of Fig. 2; u

Fig. 6 is' a sectional view on the line 6--6 of 30 Fig. 2; and v Fig. 7 is a sectional view on the line '77 of Fig. 3. v

Fig. 8 is a diagrammatic view of a modified form of the invention; 35 Figs. 9 and 10 are diagrammatic cross sections illustrative of the direction of the forces tending to distort a structure of the present invention from pressure within and outside the same,

- respectively. 40

In detail:

The invention, as shown, contemplates a junction between conduits 1, 2 and 3, each of which may be of approximately cylindrical or conical form and, in the instance of Figs. 1 and 2 are symmetrical in their arrangement with respect to the larger conduit 1, the branching conduits 2 and3 intersecting with a small angle between their axes so that the outline of their plane of intersection is somewhat of the shape depicted by the stay plate shown in Fig. 3.

In the plane of this intersection is disposed a stay plate 4 of the form shown in Fig. 3

which, on its principal peripheral edge, is provided with a groove 5 dividing the edge into 55 two portions having terminal peripheries of substantially the same thickness as the stock of which the conduit portions 2 and 3 are formed, while the balance of the periphery of the stay plate 4 may be cut away as indicated at 11 for purposes to be hereinafter set forth.

When the surfaces of the conduit portions 2 and 3 intersect, a structure is formed which has a cross sectional configuration somewhat as diagrammatically illustrated in Figs 9 and 10, that is to say the continuity of the walls of each conduit portion or section 2 and 3 is interrupted for a considerable portion of its length in the plane of the intersection and results in a weakened structure inherently tending to destroy itself. In the complete circular or cylindrical structure as before stated, pressure within places all the metal of the walls under tension, the forces tending to part the same being tangents to the periphery of the cross section as indicated by the arrows in Fig. 9.

In Fig. 9 the plane of the intersection is indicated by the double ended arrow C-D and the points of which indicate the stress directions when the conduit junction is under pressure; if the pressure Within the conduit junction should be negative there, of course, would be an opposite tendency, namely destruction by collapse. Therefore in order to restore the strength taken away by the interruption of the conduit walls due to the intersection, without increasing the wall thickness, the present invention locates in the plane of the intersection a stay plate of the form shown in Figs. 3 and land in which the flanges 6 and '7 formed by the groove 5 are bent to conform to the configuration of the edges of the intersecting surfaces so that the meeting is as shown-in Figssl, 5 and 6 and with the meeting edges all of the order of thickness of the main walls of the intersecting portions, though the body portion of the stay plate 4 may be somewhat thicker, thus providing meeting edges which are welded together as at 8 and 9, and which, due to their uniform thickness facilitate welding without the liability of burning any portions as might be the case, as before stated, where thick and thin sections are Welded together.

The edge of the stay plate 4, as indicated at 11, is resected to reduce weight, conserve metal, and provide an increased area for flow over that which would be provided if the stay plate were carried in a straight line across the line X-Y of Fig. 2.

In the event of a negative pressure in the conduit junction the stay plate 4 performs the function of supporting the structure against collapse, the direction of the stresses being indicated by the arrows as shown in Fig. 10. c

When the conduit junction is non-symmetrical with respect to the large conduit, the stay plate may take a different form to counteract other forces which are set up by the change in direction of the flow, as, for instance, is diagrammatically illustrated in Fig. 8, in which the conduit 1 is joined to two intersecting conduits 2 and 3 which have their axes non-symmetrical with respect to the axis of the conduit 1 in this situation flow in the direction of the arrows results in a difierential in pressure between the surfaces 10 and 10 the surface 10, for instance, having a higher pressure thereagainst than the surface 10, these forces being in addition to the opposite tension stresses set up by pressure within the conduit as previously described, as a consequence more metal is used on the face 10 so that the differential in pressure between the faces 10 and 10 results in the metal on the side opposite the face 10 being placed under compression, and the preferable form of this stay plate 4 under these conditions is a lens shape.

While, in the foregoing, the description relates especially to steel plate structures, the invention is equally applicable to cast or forged or concretestructures, and the size may be anything from a small pipe fitting to the large penstocks hereinbefore referred to as now proposed for the Hoover Dam without departing from the spirit and scope of the invention as claimed.

The preceding description has particular reference to forming Y-fittings, but the invention is also applicable in principle to multiple branch arrangement whether the branches are symmetrical or not.

We claim- 1. In a conduit junction, intersecting branches producing a discontinuation of the normal wall of each branch, a stay plate of greater thickness than the body plate of either branch disposed in the plane of the intersection, the edge of said stay plate being divided to provide a joining edge with the body plate of the intersecting branches of approximately the same thickness dimension as the body plate of the branches, and welding joining the parts only along the edges of approximately equal thickness.

2. In a conduit junction, a cylindrical body, intersecting conical branches welded thereto and producing a discontinuation of the normal wall of each branch at the plane of intersection, a stay plate of greater thickness than the body plate of either branch and disposed in the plane of intersection, the edge of said stay plate being divided and reduced in thickness to provide a joining edge with the body plate of each branch of approximately the same thickness as the body plate, and welding joining the parts only along the edges of approximately equal thickness.

'3. Ina conduit junction, a cylindrical body, intersecting branches joined thereto, said branches producing a discontinuation of the normal wall of each branch where they intersect one another, a stay plate of greater thickness than the body plate of either branch and disposed in the plane of the intersection, the edge of said stay plate being divided to provide a joining edge with the body plate of the branches of approximately the same thickness as the body plate of the branches, a bulk of metal on the higher pressure side of said stay plate whereby the metal is placed under compression by the differential pressure on the two sides of said stay plate and welding joining the parts only along the edges of approximately equal thickness.

JAMES E. TRAINER. BENJAMIN H. MILLER.

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