US2443851A - Spring loaded safety valve - Google Patents

Description

June 22, 1948. J L CORCQRAN 2,443,851

SPRING LOADED SAFETY VALVE Filed Jan. 14, 1947 frzye'zioz' Mal. afar warm I ciflcally as illustrated the spring ne e a 9.

auam srama LOADED ear-err vsavs 1 James L. Corco'ran, Bridgeport, c "an" nnlng, Maxwell & Moore, 111

to Ma New York, N. Y a corporation of New Jersey a f Application January 14, 1947, Serial No. 121,011:

This invention pertains to spring-loaded safety valves such as are customarily employed to release excessive pres-sure from a fluid pressure container such as a steam boiler or oil still. 1

Such a valve is illustrated, merely by way of example, in Patent No. 2,293,799. granted August 25, 1942, on an application tiled in the name of Briscoe, and, as illustrated therein, comprises a hollow casing or body which houses a valve seat and a movable valve head or ieatherwhich has a lateral delivery passage. The movable valve head ls loaded by means of a coiled compression spring arranged within a bonnet mounted on top of the casing proper. This bonnet is usually a castin and being a casting must be made heavy to insure the requisite strength. This heavy bonnet casting is of such an irregular shape that it is hard to handle during the machining operations. and hence it is dlillcult to finish it in such a manner as to insure a straight line thrust of the loading sprlna ,silien the parts are assembled. The base flange of the bonnet casting is usually secured to the casing proper by means of six or more bolts, an'dthe assembly of. the bonnet with the casin thus-involves the insertion of these bolts and the proper tightening of the nuts. Moreover, as the bonnet is of fixed dimensions, the exchange of one loading spring 201 another which is longer or shorter. as is sometimes desirable in order to adapt the valve for use with a; different pressure range, involves expensive machining of the bonnet or its exchange for another.

' It has heretofore been proposed to transmit the springpressure to the casing simply by means of a pair oi diametrically opposite tension .rods instead of the usual cast bonnet, but as heretofore devised a pair of tension rods has not been found satis'iactory because such rods oiierbut little resistance .to force exerted in a direction transverse to the plane defined by the axis or the rods, and thus thisarrangement, although simple and having many advantages, has not, been widely, adopted. Furthermore such an arrangement of the tension rods does not insure accuracy of alignment of the spring thrust. h

One-object oi the present invention is thereiore to provide a bonnet structure of the kind wherein the spring load is carried by a pair or tension rods but so devised as to provide the requisite stillness transversely of the plane of the rod axes to prevent bending of the rods in response to usual iorce. More speload is transmitted to, the casing by oi two parallel diametrically spaced tension rods. but-with prothe application any vision for supporting said rods at points intermediate their lengths, thereby to support them in opposltiontobendlng stressed f p Aiurther object is to provide a safety valve wherein the bonnet structure is simplalight in weight and stronger than the usual bonnet casting and which may be more cheaply and which may be assembled more easily with the cos-- ing than the usual cast bonnet. A further oblect is to provide a bonnet "structure such. that the spring load is carried by rods of a relatively high tensile strength as compared with cast rods and which may be made mm standard bar stock. A further object is to provide a bonnet structure wherein the bridge which supports the abutment for the upper end or the spring maybe 0! standard rolled stock instead 61' a casting. thus decreasing weight while insuring adequate stillness. A further object is to provide a valve so devised that the machiningoperation requisite to the atta'chment of the bonnet to the casing may all be carriedout from the top oifthe casing, thus slmpliiying the procedure and insuring accuracy 01 align-1 ment of the parts. -()ther and further objects and advantages of the invention will be pointed out in the following more detailed description and by reference wherein a Fig. l is a vertical section through a springloaded sale'ty valve embodying the invention, the

' section being in a plane P ndicular to the vertical plane of the axis or thedelivery passage; and Fig. 2 isa fragmentary horizontal section to smaller scale substantially on the .line 1-1 oi Fig. 1 and showing the casingproper without other parts. z 1

Referring to the drawings, the illustrated valve comprises a bodyor casing proper I usually a casting or forging having. a bottom flange-2 by means oi which it is securedto a pressure container such as a boilen'sup'erheater or the like.

the flange 2 being united'to the body by a neck portion 3 or smaller" diameter than the body proper. A seat-supporting sleeve 1 or the general type disclosed in Patent No. 1,668,453, to

Graesse'r 'et ai.. granted May 1, 1928, is here shown as secured within the neck I of the valve body and in coaxial relation to the neck, this sleeve deilnini a vertical inlet passage I and having a valve seat at its upper end.

valve seat is located wig hin a delivery chamber 8 in the casing body,.thls delivery chamber opening into a-discharse passage .(l'lg. 2)

' whpse axis is substantially perpendicular to the axisoitl'ieinletpassa'gfl.-

to the accompanying drawings A rigid annulus I8 is fixed to the top of the casing by bolts II. This annulus l9 constitutes clamping means for securing the horizontal flange. of a guide sleeve l2 to the casing body, this guide sleeve l2 having a vertical bore accurately aligned with the valve seat and which forms a guide for the cylindrical skirt portion l3 of the valve head. The valve head has an axial socket for the reception of the lower end of a. valve-actuating pindle IS. The spindle extends up through the annulus l9 and through a steam deflecting shield l5. Above the shield IS the spindle has a shoulder I! which forms a support for a lower abutment disk is on which rests the lower end of a coiled compression spring I9. The upper end of the compression spring, by means of which the valve head is urged toward the valve seat, bears against an upper abutment disk 20, the latter resting against the lower end of an adjusting sleeve 2| surrounding the spindle and having screwthreaded engagement with a bore at the center of a transversely elongate bridge 22. This bridge is preferably of rolled bar stock and of sufllcient thickness and rigidity so that it is not substantially deflected when subjected to the full load imposed by the spring IS. The valve spindle l extends up through the sleeve 2| and is provided at its upper end with an abutment collar which is engaged by the usual valve-lifting lever 23 by means of which the valve may manually be lifted from its seat.

As here illustrated the casing I is provided at diametrically opposite points with integral rigid outstanding lugs 24 and 25. These lugs are disposed above the plane of the bottom flange 2, lie substantially in the plane of the lower wall of the chamber 8, and have vertical bores therein whose axes are parallel and diametrically opposed, as respects the axis of the inlet passage 5, and in a plane preferably perpendicular to the vertical plane of the discharge passage 9. The bores in the lugs 24 and 25 receive the lower ends of tension rods 26 and 21. These rods preferably are standard bar stock turned to the shape here illustrated and are of steel of very high tensile strength. By the employment of the steel of high tensile strength it is possible to reduce the diameters of these bars and thus very substantially reduce the weight of the bonnet structure, as compared with the usual cast bonnet.

The rods 26 and 21 are provided near their lower ends with shoulders 30 and 3| which rest upon the upper ends of the lugs 24 and 25, respectively, and are screw threaded at their end portions for engagement with nuts 32 and '33, by means of which they are securely anchored to the lugs 24 and 25. 1

Near their upper ends the rods 25 and 21 are of alignment of the bores in the lugs 38 and 24,

furnished with shoulders 34 and 35 which engage the under side of the bridge 22 bordering bores formed in the opposite end portions of the bridge. The rods extend up through these bores and their end portions are screw threaded for engagement with nuts 36 and 31, respectively, by means of which the rods are securely clamped to the bridge.

In accordance with the present invention, the casing l is provided with a second pair of diametrically opposed lugs 38 and 39 extending outwardly from its opposite sides and spaced directly above the lugs 24 and 25. These lugs 38 and 39 are situated above the plane of the valve seat substantially at the top of the valve casing and have vertical bores therein axially aligned with the bores of the lugs 24 and 25. The rods 28 and the same accuracy of alignment being true of the bores in the lugs 39 and 25. Thus, when the rods are passed through the bores of the lugs 38 and 39 and secured in the bores in the lugs 24 and 25, the rods are accurately parallel and held very rigidly in this accurately parallel relation by the lugs 38 and 39 which, in effect, constitute bearing sleeves and which sustain the tension rods in opposition to bending force which might tend to throw them out of parallelism.

It may be noted that the two pairs of lugs 24-25 and 38-39 project but a short way from the body of the casing so that they are very rigid and devoid of any tendency to bend in response to load even though they are not of very large dimensions. Likewise since the axes of the tension rods are quite close to the casing body there is little tendency to distort the latter, even though the walls of the body be quite thin.

While, as here illustrated, the bores for the reception of the rods are formed in lugs projecting oppositely from the casing body, it is within the scope of the invention to provide the casing body with continuous peripheral flanges in which these bores may be formed, such flanges, if employed, adding stiffness and rigidity to the casing body, which may be desirable under some conditions.

Likewise, although but two diametrically opposed rods are here illustrated, it is within the scope of the invention to provide more than one pair of such rods, and in the latter event the rods employed would obviously be disposed symmetrically with respect to the axis of the inlet passage and in such a manner as to avoid interference with the delivery passage.

Other and further modifications and rearrangements are to be regarded as falling within the scope of the appended claims.

I claim:

1. A safety valve of the kind which comprises a hollow casing housing a valve seat and a movable valve head, and which has an inlet passage coaxial with the seat and a discharge passage whose axis is substantially perpendicular to that of the inlet passage, a compression spring for loading the valve head and a bonnet structure including a transversely elongate a bridge which supports an abutment for the upper end of the spring, and a pair of diametrically opposite, parallel tension rods whose axes are in a plane perpendicular to the horizontal diametrlcal plane of the discharge passage, the casing having apertures for the lower ends of the rods disposed in a plane below the plane of the valve seat, means securing the lower ends of the rods in the respective apertures, the bridge having apertures at its opposite end portions for the upper ends of the rods, and means securing the upper ends of the rods in said latter apertures; characterized in having rigid bearing sleeves which grip the rods intermediate their ends, thereby to oppose forces tending to bend the rods, said bearing sleeves being integral portions of the casing and located near the top of the latter.

2. A safety valve of the kind which comprises a hollow casing housing a valve seat and a movable valve head, and which has a compression spring for loading the valve head and a bonnet structure including a transversely elongate bridge adapted to support the upper end of the spring, and a pair of diametrically opposite, parallel tension rods, the upper ends of which are secured in the opposite ends of the bridge and the lower ends of which are secured in lugs iormed integral with the casing in a plane below the valve seat, characterized in that the casing has other integral bearing lugs disposed in a plane above that of the valve seat, said latter lugs having vertically elongate bearing openings axially aligned with the openings in the first mentioned lugs for receiving the lower ends of the rods, the apertures in the bearing lugs being of a diameter to receive the respective rods with a snug fit, thereby to brace the rods 'in opposition to bending forces.

JAMES L. CORCORAN.

REFERENCES crrEn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 860,797 Gaudin July 23, 1907 2,278,437 Gentzel Apr. 7, 1942

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