US1601845A - Stay bolt - Google Patents

Description

Oct. 5,1926. I 1,601,845

R. S. BOOTH v STAY BOLT Filed Feb. 13, 1924 1; L? 1 h w 7 y 5 f v ATTORNEYS til tenses ..,ran stares rarest orFicE.

ROBERT SINCLAIR BOOTH, OF WASHINGTON, DISTRICT OF COLUMBIA.

- STAY BOLT.

Application filed February 13, 1924. Serial No. 695,469.

This invention relates to flexible telltale staybolts for boilers, and, more particularly, for locomotive boilers; ject the provision of certain expedients for continuing the tell-tale hole to the atmosphere surrounding the exterior of the boiler for more readily detecting defects in such staybolts.

Rigid staybolts having tell-tale holes extending their entire length, or, at least, 1

inches deep from the outer end, have been universally employed for many years in the construction of locomotive boilers. Such staybolts are subjected to excessive strain resulting in their fracture due to the unequal movement of the inner and outer sheets of the boiler or firebox caused by unequal expansion and contraction with changes in temperature. For this reason rigid staybolts, in spite of their advantage of having a tell-tale hole extending their entire length, have been replaced in a number of locomo tive boilers and fireboxes by so-called flexible staybolts. These flexible staybolts originally had no tell-tale hole, but lately have been equipped with a tell-tale hole extending only to one end and communicating with the flre box. The flexibility of such staybolts de: creases their liability to fracture, and for this reason they have been employed in the construction of certain portions of locomotive boilers and fireboxes in preference to rigid staybolts. The art clearly recognizes the utility of staybolts having a tell-tale hole extending their entire length or communicating with the exterior of the boiler and the atmosphere, as an element of safety. The ederal law governing maintenance of locomotive boilers and the Interstate Commerce Commission, which is charged with the enforcement of said law, also recognize this fundamental principle.

Flexible staybolts now commonly employed are rigidly secured to the inner sheet shell or firebox side of the boiler and are flexibly connected with the outer or exterior sheet or shell of the boiler. The flexible connection is closed by a cap or other suitable closure for preventing leakage of water or steam. It has been found impracticable to employ a flexible connection associated with the inner sheet shell or firebox side of and has for its ob the boiler due to excessivecorrosion or other deleterious effects caused by high temperatures. v

The present invention contemplates the provision of certain expedients for continumg the tell-tale hole in flexible staybolts to the atmosphere by extending the tell-tale hole to the exterior of-t'he boiler without interfering in any substantial manner with the flexibility of the staybolt. Thus a flexible tube appropriately secured in the staybolt may extend through the cap or closure so as normally to prevent communication between the boiler and the tell-tale hole and continue the latter to the exterior of the boiler or to the atmosphere. The tube may be constructed of any suitable flexible material such as copper, lead, steel, brass, or aluminum, etc. The closure should be positioned a considerable distance from the head of the staybolt to permit considerable flexure of the tube. The flexibility of the tube may be increased in various ways, such, for example, as reducing in cross-section a portion of the tube. Or the flexibility of the tube may be increased by curving the tube in the form, of a loop or winding, making a complete or partial turn.

The tube may be welded in the staybolt or closure, or otherwise secured therein in any suitable manner to make an appropriate tight connection therebetween. Thus, the tube may be tapered at its ends for embedding in the staybolt and the closure. Gr, alternately, the tube may be threaded at its ends and screwed into the staybolt andclosure, and, if desired a nut or nut and gasket may be secured to the end of the tube in contact with the closure to make a tight connection therebetween. I

These and other features of the invention will be more clearly understood by reference to the following description and accompanying drawings; in Wl1lOl1-- Fig. 1 is a sectional view of a flexible staybolt assembled in, a boiler;

Fig. 2 is a plan view of the same; and

Figs. 3, 4:, and 5 are partial sectional views of modified forms of the staybolt construction of the invention.

A staybolt 6 having a tell-tale hole 7 is screwed, or otherwise rigidly secured, at one 12, as shown in Fig. 3.

as that previously described, or

end to the firebox shell 8 of a boiler to make a tight joint. The other end of the staybolt is flexibly mounted upon the outer side of the exterior shell 9 of the boiler. Preterably, this end of the staybolt is rounded to bear upon the inner spherical surface of acollar or sleeve 10 which is appropriately secured to the outer surface of the shell 9. The flexible connection between the staybolt 6 and the collar or sleeve 10 is closed by a removable cap or closure 11 to prevent leakage of water or steam.

A. flexible tube 12 of any suitable material, such as copper, or lead, is appropriately secured in the end' of the'staybolt 6 and extends through the closure 11 to continue the tell tale hole 7 through the closure. The tube 12 may be screwed into either or both the staybolt and the closure to make a water or steam tight joint, or the end of the tube 12 may extend through the closure 11 and engage a threaded nut 13 having a small depending circular projection 14 adapted to contact with a ga ket 15 on the closure 11. Alternately, the tube 12 may have its ends tapered in the same or opposite directions and adapted to be embedded in the end of the staybolt and in the closure as shown in Figures 4 and 5.

The flexibility of the tube 12 may beincreased by reducing in cross-section a por tion of its length. In certain portions of the boiler where the relative movement of the boiler shells is excessive, I propose to employ a modified form of a flexible tube The flexible tube 12 may be secured to the staybolt 6 and closure 11 in any suitable manner to make a water tight and steam tight connection, and

extends in a curved or winding path so as to form a complete or partial turn 'therebetween. If desired, the head of the'staybolt 6 may be flattened to provide increased space between the staybolt and the closure. construction of flexible tube permits free turning of the staybolt in its flexible bearing without danger of causing fracture in the flexible tubular extension because of the increased flexibility of the tube in all directions.

The provision of a flexible tube in accordance with the invention continuing the telltale hole to the exterior of the boiler and to the atmosphere will not materially interfere with the flexibility of movement of the staybolt, and willallow the discharge of steam or water to the atmosphere when the staybolt becomes fractured sufficiently at any point to extend to the tell-tale hole, thus giving an automatic alarm in case of weakness or danger.

It will be understood that the flexible tube may be secured to the stayboltv and cap or closure in any manner whatsoever, such by auto- This the same direction genous welding, or by expanding, belling, or beading the tube to make a steam tight fit.

As now required by law, the cap or closure must be removed at stated intervals for inspection of the staybolt and to permit suit-- able test being made, such, for example, as hammering the end o1 the staybolt to detect weaknesses or defects; it is also common practice to determine whether or not the tell-tale hole is open by inserting a plunger therein from the fire-box to make an electrical contact With'the bottom of the hole. The provision of the tubular extension of the tell-tale hole'to the exterior of the boiler and atmosphere in accordance with the present invention should render unnecessary the removal of the cap or closure for inspection and should eliminate such'other frequent tests as are now commonly required, inasmuch as any impending danger due to a weakness or defect immediately apparent by the discharge of water orsteam.

The invention is applicable to boilers of any type wherever it is necessary or desirable to stay the sheets or shells of a boiler or the sheet shell of a boiler firebox. Throughout this specification and the appended claims I intend the term shell to refer to or include the shell or sheet of a boiler, or the sheet shell of a boiler firebox, or any other element with which a staybolt is ordinarily associated.

1 claim 1. In a flexible tell-tale staybolt construction for boilers, a tell-tale staybolt having a flexible connection with the shell of the boiler, a closure for the flexible connection so positioned relative to the staybolt as to provide a relatively large space therebetween, and a flexible tube extending through and secured to the closure and fixed to the head of the staybolt to thereby extend the tell-taleto the exterior of said closure.

2. A staybolt having a flexible connection with the shell of'a boiler, a closure for the flexible connection, a tell-tale hole in the staybolt, a flexible tube secured in the closure and'terminating in the head of the bolt and continuing the tell-tale hole through the closure said tube having tapered ends adapted to 'be embedded in the staybolt and in the closure to make a tight connection therewith.

3. In a flexible tell-tale staybolt construction for boilers, a tell-tale staybolt adapted for flexible connection with the shell of the boiler, a closure forthe flexible connection, said staybolt being so constructed and so positioned relative to the closure as to providea relatively large vspace therebetween, and a flexible tubejhaving ends tapered in and extending through.

and secured to the closure and fixed to the in the staybolt is rendeed' head of the staybolt to thereby extend the to continue the tell-tale hole therethrough, tell-tale hole to the exterior of said closure. said stay-bolt having a flattened head to pro- 4. A staybolt having a flexible connection vide increased space between the staybolt 10 with the shell of a boiler, a closure for the and the closure. 5 flexible connection, a tell-tale hole in the In testimony whereof I aflix my signature.

staybolt, a flexible tube secured in the closure and terminating in the head of the bolt ROBERT SINCLAIR :BOOTH.

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