US2058030A - Retainer for fluids under pressure - Google Patents

Description

' Oct. 20, 1936. .'s. MILLER 2,058,030

RETAINER FOR FLUIDS UNDER PRESSURE Filed May 25, 1956 INVENTOR She/man M///e/' ATTORNEY.

Patented Oct. 20, 1936 RETAINER FOR FLUIDS UNDER PRESSURE Sherman Miller, Schenectady, N. Y., assignor to American Locomotive Company, New York, N. Y.', .a corporation of New York Application Ma 23, 1936, Serial No. 81,406.

. 4 Claims.

This invention relates to retainers for fluids under pressure.

The object of this invention is to provide a novel closure for an end of the shell of the retainer, whereby a better closure is provided than the usual closure, and particularly than the onepiece flanged head or closure of the usual retainer for fluids under pressure, such as a steam generator, and whereby manufacture and repairing 1 is .cheapened.

The invention .has special application to a fire tube type of steam generator or boiler and, for illustrative purposes, such a generator is shown in the drawing. to .In the accompanying drawing Figure 1 is a fragmentary longitudinal section of parts of a conventional fire tube type of locomotive boiler taken on the line ,II of Fig. 2, embodying the present invention; Fig. 2 is a section of the boiler 1;! taken on the line II- -II of Fig. 1; Fig. 3 is an enlarged fragmentary .section taken on the line III III of Fig. 2; Fig. 4 is an enlarged view of the upper portion of Fig. 2; Fig. 5 is a section through the line V-V of Fig. 4; and Fig. 6 is a 2.5 fragmentary enlarged view similar to. the upper portion of Fig.2, showing a modified construe-- tionl The present invention applies to retainers for fluid .under pressure generally, but has special apto plication to a steam generator, and particularly to the fire tube type of generator usually employed in steam locomotives, and therefore the following description will bear more particularly onsuch .a generator, an illustration of which is shown in the accompanying drawing insofar as is necessary for the present invention.

In steam locomotive practice, as is well known, the conventional steam generator section in advanw of the firebox section comprises a cylin- 40 drical shell for the Water and generated steam more or less filled with longitudinally disposed fire tubes which connect the flreboX' with the smokebox and which transmit the heat of the products of combustion passingtherethrough to the water for generation of vthe steam contained in this boiler section. This boiler sectionisclosed at the front end by a head member, more commonly termed a tube sheet, in which the tube front ends are secured. The usual practice has been to bend this tube sheet at its peripheral margin over at a right angle to providea circular flange which engages the cylindrical shell to which it is riveted, 'to provide a fluid-tight joint. It is -difficult,1if not impossible, to make a circular flange in this way that will snugly fit the cylindrical .shell, and therefore some distortion must beresorted to to draw the flange and shell together by the rivets to make a fluid-tight'joint. As a matter of fact the formationrof the-shell does not result in providing a perfect cylinder, :5, and neither does the formation of the flange result in providing a perfect circler This is particularly true in modern large boilers where the shell .may reach seven feet in diameter, and one inch in thlckness'and the tube sheet approximate- 10 1y one-halfinch in thickness. Moreover, during the life. of the boiler, replacement of the tube sheet is sometimes necessary, and. to remove the one-piece tube sheet of the flanged over type and to manufacture and install another. tube sheet is very troublesome and costly. The present invention is directed .to overcome these various difficulties.

In the accompanying drawing the front portion 'I of the fire tube section of .a locomotive ,zo boiler is shown for illustrativepurposes, although it will be understood that the invention applies to any retainer for fluid pressure involving an end .closure. It comprises a cylindrical shell 2 and fire tubes 3. The tubes shown are the larger .25 ones used usually for superheater elements, and it will be understood that, in practice, other and similar tubes willalso be employed, the tube sheet being perforated, in the usual mannen for receiving all such tubes. a

In the present instance the rear. end portion 4 of the. smokebox of the boiler is shown, the

wall 5 .of this box beingshown, as in usual practice, as a vcontinuationof theshell 2.

The closure of the presentinvention is of com- .35

posite structure and is indicated generallyby the numeral 6. .--It comprises a band member shaped to conform to the shell, and in the present illustration of the invention, as the shell is cylindrical, the band member is circular to form a 9 ring I, as shown. The band member may be shaped around the shell to conform accurately to the inner face of theshell, and thereafter any surplusage cut off, and the ends butted together, thereby making a tightfit with the shell, the ends being welded if desired, or the ring may be made in any other manner desired.

While theband may, broadly speaking, be of any contour, it will, for convenience, in the fol ,50

lowing description, be termed a ring, it being so illustrated in the drawing, and likewise the retainer .will be referred to as a'boiler. The face 8 .of the ring, the inboardface considered as re- .gards the Sshelll of the boiler, is welded to the F inner face 9 of the shell by a fillet weld II! which extends entirely around the shell, and a similar weld H connects the outboard face l2 of the ring to the inner face of the shell. These welds firmly secure the ring to the shell to firmly hold the composite closure against the pressure of the steam (or other contained fluid, as the case may be), and provide a seal for the steam and water between the ring and shell, preventing leakage of the fluid. The closure further comprises a head member, which in the present case is a tube sheet 13, which head member, for reasons similar to those stated above, will be termed a tube sheet, although, as to these specific terms, it will be understood the appended claims are not thus limited unless so specified therein.

In assembling the members forming the closure the ring is first applied, and there will be no necessity for thereafter removing the ring when repairs are made to the boiler necessitating the removal of the tube sheet. The ring may be riveted to the shell, but preferably, as in the present illustration, it is secured entirely by welding. As the ring is assembled before the tubes or tube sheet are applied there is ample room within the shell for the welder to apply the weld ID to the inboard side of the ring, and as the ring is not removed when repairs are made, the weld I0 is not disturbed. This presents a material advantage of the composite closure, especially in the case of a fire tube boiler construction, for it would not be practical to so secure a one-piece flanged tube sheet, and instead thereof riveting, from a practical standpoint, must be resorted to, for with the tube sheet of the usual construction forming an integral part of the flange, the tube sheet and flange would have to be removed when replacement was necessary, and this could only be done by removing the welds, and could only be accomplished with much trouble and expense.

The ring I is provided with a pair of oppositely disposed passageways I4 and I5 running longitudinally of the shell and open at the inner face l6 of the ring. These passageways are of a width sufficient to permit opposite edge portions of the tube sheet to respectively pass through said respective passageways, and their bottoms l1 are sufl-lciently spaced apart to permit of said passage of said tube sheet.

In assembling or removing the tube sheet it is thus passed through the enclosure formed by the ring (Figs. 1 and 2 showing the tube sheet in dot and dash lines in its passage through said enclosure). When assembling the tube sheet, it is thus passed through this enclosure to the enclosure provided by the shell, and is then turned to the position shown in section in Fig. 1 in engagement with the ring. After it is secured in position, as will later be described, the fire tubes are applied in the usual manner. When removing the tube sheet the operation is merely reversed. In the case of the fire tube boiler the tubes are first removed from the tube sheet, in the usual manner, and after the necessary welds are removed, the tube sheet is then turned within the boiler until it assumes a position where it can be passed through the passageways in the ring to the exterior, whereupon a new tube sheet may be assembled. While generally heat exchangers will contain tubes, of course in instances where there easy working fit between the tube sheet and the passageways, as the former is passed through the latter, and this results in there being a slight opening l8 adjacent the bottom of each of the passageways, that is to say the tube sheet does not entirely cover the inboard end of the passageways. It is therefore necessary that these openings be entirely closed to prevent leakage of the fluid from the boiler. The tube sheet is welded at its outboard face to the ring by a fillet weld I9 which may extend entirely around the inner face of the ring, extending into the passageways about the three edges thereof to thereby span the gap provided by the openings It to entirely close these openings, this fillet weld thereby entirely sealing the seam between the tube sheet and the ring, thus preventing the escape of fluid past the edge of the tube sheet.

In the present instance, however, the fillet weld l9 stops short of the passageways, and a filler member 26 is disposed in each of the passageways. Each filler member is formed of a block of metal of a size to snugly fit the passageway and to butt at its inboard end face against the adjacent portion of the tube sheet. The filler member is preferably somewhat shorter than the length of the passageway to provide at the outboard end a space 2|, and furthermore extends out of the passageway at the inner face of the ring, this outward extended portion being preferably gradually increased from the outboard end to the inboard end of the filler member, which tends to stiffen the closure at these parts.

The filler member is secured to the tube sheet and to the ring by welds to provide a seal for preventing leakage of the fluid through the closure at these parts. In the present instance this is accomplished by providing fillet welds 22 along the three edges of the outboard end face of the filler member and the adjacent faces of the passageway; fillet welds 23 between the sides of the filler member and the adjacent portions of the inner face of the ring; and fillet welds 24 between the inboard edges of the extended portion of the filler member and the adjacent portion of the tube sheet. Thus all exterior seams between the filler member and ring and tube sheet are sealed by fillet welds in a manner to form a continuous weld, thereby forming a complete seal at this portion of the closure.

It will be appreciated that the entire pressure of the steam within the boiler that is exerted against the tube sheet is taken by the ring, and that none of this pressure is transmitted to the welds between the members of the closure, namely the weld between the tube sheet and ring, and, when filler members are employed, between these members and the ring and tube sheet, except at the very small opening I8 (see Fig. 5), which is inconsequential.

Fig. 6 shows a slight modification. Here a tube sheet 25 is provided with a pair of extensions or enlarged portions 26 oppositely disposed (the view being fragmental, only one of the extensions 26 is shown, but it will be understood that the boiler is similarly constructed at the opposite side) having their outer ends spaced further apart than the distance between the bottoms of the passageways, and each being of a size to completely cover its respective passageway. Obviously in both tube sheets of Figs. 1 and 6 it is only necessary that edge portions thereof oppositely disposed be suitable as to dimensions to pass through the respective passageways, and accordingly the tube sheet 25 is provided with such oppositely disposed portions (they being, in the present instance, any oppositely disposed portions other than the portions 26), and during assembly after the tube sheet 25 is passed into the enclosure provided by the shell, it is suitably turned about until the oppositely enlarged portions or extensions 26 are brought opposite the respective passageways, as shown in Fig. 6. The tube sheet may be welded to the ring in either of the ways previously described, but, as the openings 18 are not present in the modified construction, there is not the same necessity for the filler members, and these may be eliminated if desired, and in such case the welding of the tube sheet to the ring within the passageways is more easily accomplished as there are no open spaces to seal.

The invention claimed and desired to be secured by Letters Patent is: 1

1. In a retainer for fluid under pressure, the combination of a shell providing a confining wall for said retainer; and a closure for an end of said shell comprising a band member secured to the inner face of said shell to seal the seam therebetween and to firmly hold said closure against the pressure of the contained fluid, and a head member disposed at the inboard side of said band member and engaging said band member at the inboard face thereof and welded thereto to seal the joint therebetween to prevent escape of fluid past the edge of said head member, said band member having a pair of oppositely disposed passageways directed longitudinally of said shell, each of said passageways opening at the inner face of said band member and being of a sufficient width, and said passageways being sufficiently spaced apart between their bottoms, to permit opposite edge portions of said head member to respectively pass through said respective passageways, whereby said head member may be passed edgewise through the enclosure provided by said band member into and out of the enclosure provided by said shell preliminary to assemblage and replacement respectively of said head member, said head member being of a contour substantially similar to, but somewhat smaller than, the inner contour of said shell at the part thereof opposite said head member.

2. In a retainer for fluid under pressure, the combination of a shell providing a confining wall for said retainer; and a closure for an end of said shell comprising a band member secured to the inner face of said shell to seal the seam therebetween and to firmly hold said closure against the pressure of the contained fluid, a head member disposed at the inboard side of said band member and engaging said band member at the inboard face thereof, said band member having a pair of oppositely disposed passageways directed longitudinally of said shell, each of said passageways opening at the inner face of said band member, and being of a suflicient width, and said passageways being sufficiently spaced apart between their bottoms, to permit opposite edge portions of said head member to respectively pass through said respective passageways, whereby said head member may be passed edgewise through the enclosure provided by said band member into and out of the enjoined by welds providing a sealing of said members together to prevent leakage of said fluid through said closure, one of said welds being at the seam between said head member and said band member at the outboard side of said head member.

3. In a fire tube steam generator, the combination of a cylindrical shell providing a confining wall for said generator; and a closure for an end of said shell comprising a ring engaging the inner face of said shell and fillet welded thereto at the inboard seam between said shell and said ring, and a tube sheet provided with orifices engaging the fire tubes of said generator, disposed at the inboard side of said ring, and engaging said ring at the inboard face thereof and welded, at its outboard side, to said ring to seal the joint therebetween to prevent escape of fluid past the edge of said tube sheet, said ring having a pair of oppositely disposed passageways directed longitudinally of said shell, each of said passageways opening at the inner face of said ring and being of a sufficient width, and said passageways being sufiiciently spaced apart between their hottoms, to permit opposite edge portions of said tube sheet to respectively pass through said respective passageways, whereby said tube sheet may be passed edgewise through the enclosure provided by said ring into and out of the enclosure provided by said shell preliminary to assemblage and replacement respectively of said tube sheet, said tube sheet being of a contour substantially similar to, but somewhat smaller than, the inner contour of said shell at the part thereof opposite said tube sheet.

4. In a retainer for fluid under pressure, the combination of a shell providing a confining wall for said retainer; and a closure for an end of said shell comprising a band member secured to the inner face of said shell to seal the seam therebetween and to firmly hold said closure against the pressure of the contained fluid, and a head member disposed at the inboard side of said band member engaging said band member at the inboard face thereof and welded at its outboard side to said band member to seal the joint therebetween toprevent escape of fluid past the edge of said head member, said band member having a pair of oppositely disposed passageways directed longitudinally of said shell, each of said passageways opening at the inner face of said band member and being of a sufficient width, and said passageways being sufflciently spaced apart between their bottoms, to permit a pair of oppositely disposed edge portions of said head member to respectively pass through said respective passageways, whereby said head member may be passed edgewise throughthe enclosure provided by said band member into and out of the enclosure provided by said shell and suitably turned when within said shell enclosure preliminary to assemblage and replacement respectively of said head member, said head member being somewhat smaller in area than the cross-sectional area of the shell enclosure at the part where said head member is located, and said head member being of a contour providing a space between said shell and the edge of said head member, said head member being provided with another pair of oppositely disposed edge portions, said last mentioned portions being spaced farther apart between their outer ends than the distance between the bottoms of said passageways, said last mentioned portions being disposed respectively opposite the respective passageways and being of a size to completely cover same.

SHERMAN MILLER.

Images