US2267183A - Stuffing box - Google Patents

Description

Dec. 23, 1941. G. H. WILLIAMS 2,267,183- 4 STUFFING Box l File'd July 17, 1939 2 sheets-sheet 1 Y u HH III/ll Dec. 23; 1941. v c-:Lv H, WILLIAMS STUFFING BOX Filed July 17, 1939 2 sheets-sheet 2 f GMW/v H. WML/AMS BY' t A TTORNE Y..

Patented Dec. 23, 1941 ljNlT E D STAT S Zemst ar e r orrice application July 1c, 1939,l serial Naasama 2y Claims.

My` invention relates to stu-ning boxes and has particularl reference to an improved stuffing box for packing ofi around a reciprecating rodsuchas the` polished rod of an oil well pump.

In theY pumping off oil wells it is the commonpractice to-emplcya plungerl and barrel ty'pe of pump located deep within the well, from which a string of sucker rodsextends to the ground surface for connection toA a reciprocating pumping jack or other power mechanisr-nby which the suckerV rods and plunger are reciproca/ted'.

rlhe upper end section oi the sucker rod string is usually formed as a polished red which passes throughv a stuffing box at the well head which will prevent leakage of oil' around the polished rod whil'e permitting free reciprocatory movement thereof. Whilethe ideal condition for maintaining the sealing action of the stuiiing box over prolonged periods' of operation is that of reciprocating the polishedV rod through the stuffing boxin a Vertical linecoincident with the axis of the tubing within which it operates, it is found that` this ideal' condition is seldom encountered. The polished rod may be shifted from such axial relation even though its path of movement may be ina direct Vertical line or the polished rodmay shift laterally during each cycle of its movement so that in stuf-iingboxes in which the packing is rigidly mounted such packing',

becomes rapidly worn.

The pumping apparatus which ismost ccmmonly employed for reciprocating the sucker rod string is of the walking beam type inv which a walking beamis pivoted to reciprocaterina vertical planewith one of its ends disposed immediately above the well head and-'to which a cable or other connecting device is secured and,

coupled to the polished rod. It fellows that,

though thepolished rod will be reciprocated in a substantially vertical direction, thearcuate path described by the outer end'- of the walking beam willi produce a lateral shifting of the-I upper end of' the polished rod during eachstrokef. Thus the polished redwill be forced laterally iirst against one side-'andi then the other of the packing employed in: the stuft-ing box, rapidly wearing such packing so. that itV no longer makes a sealing t. with the polished rod. Even though devices suchA as horse headsy are used on the walking beam, tominimize such lateral shifting ofthe polished an appreciable shifting irequently occurs with the attendant rapid wearing out of the packing and loss of seal.

It is therefore an object of my invention to provide a stuing ocx of the character described, in which the packing surrounding the polished rod may shift laterally in all directions to compensate ior misalignment of the power apparatns andy may also assume diiierent angular positions coincident with the tilt of the axis of the polished rod.

o along the rod and in which` the` packing unit. is ,so mounted within4 a, housing; as'to permit. the.l

entire unit: to, shift bodily alli lateral` directions as well as to permit either; end or the pack.'- ing unit to be shifted laterally different amounts l and in diiierent" directionsi Another objecty of my invention is; to provide a device of: the; character set forth wherein Vslide bearings are' provided for eachv endof the; pack:- ing unit upon which the packing unit may float ln freely in alli lateral f directions and in which the "lslidebearings will permit; constant shifting without unduey wear. Y

Another object of 'my invention is tor provide a.

device of the character set forth inY the precedingparagra-ph wherein the bearings are ccnstructed* of' readily replaceable parts.

Other objects and advantages of my invention` will be apparent from a study of the following specifications, read in connecticn-- with the accompanyin-g drawings,v wherein Y i' Fig. 1 is a vertical sectional view takenthrougha stung box construction embody-ing the prin.-

ciples of my invention and-illustrating the position4 of the parts when the polished rodl is operating along a direct vertical line axially'aligned with the housing; y

, Fig. 2, is a view similar to Fig. 1 but illustrating the position of the vparts when the motionl ofthe polished rod isy along a direct. vertical line but is 'i5 oiiset laterally from the axial alignment, with the housing;

Fig. Sis, a View similar to Fig.. 1 andC illustrating the position ofl the parts when the polished rod is moved along al path which is disposed by 40 an angle tothe vertical or to a changing angle I during difierent parts of the cycle of movement of the polished rod;

Fig. 4 is a diagrammatic View of an oil well pumping apparatus illustrating the circum-V stances of mis-alignment of the pumping apparatus with the axis of the well, causing the conditions depicted, in Fig. 2,; Y

Fig. 5 is a diagrammatic View similar to Fig. 4 and illustrating the circumstances which cause so a bending of the polished rod and the conditions QQjIhe housing I provides a relatively large diameter "Jfchamber 3 through Which the polished rod Il prises an elongated tube or sleeve 'I which con-..

stitutes a casing within which is disposed a plurality of packing ring 8 formed of suitable packing material. I prefer to arrange the packing rings as relatively narrow rings stacked one upon the other in two groups, an upper group including a plurality of these rings and a lower group including a plurality of these rings, the two groups being spaced apart by means of a, spacing ring 9 illustrated particularly in Fig. 6.

'I'he spacing ring 9 may be readily formed as a casting including an upper ring element I and a lower ring element Il spaced from each other by a plurality of narrow webs I2 so as to provide therebetween a plurality of relatively large radially extending openings I3 through which lubricant may readily pass to the surface of the polished rod enclosed within the packingrings and spacer rings.

The tubing 'I is preferably somewhat longer than is required to house the assembled packing and spacing rings so as to provide spaces on each end of the assembled rings into which glands I4 and I5 (constituting parts of the packing unit 6) may project, the external diameter of that portion of the glands I4 and I5 which extends into the tube 'I being preferably somewhat less than the internal diameter of the tube 'I so that while the inner ends of the glands I4 and I5 may bear directly upon the outermost packing rings there will be substantially no metallic contact between the glands and the tube 1.

The outer or lower end of the packing gland I4 is preferably machined or ground to a horizontal surface I6 which constitutes a bearing surface adapted to rest upon and slide laterally on a wear ring I'I which may be formed of relatively hard steel. In order to insure a tight and substantially liquid-proof seal between the gland I4 and the wear ring II, the interengaging surfaces may be lapped together.

A similar construction is provided for the gland I5, its upper surface I 8 being lapped upon the lower surface of an upper steel wear ring I9. Pressure is applied to the upper gland I5 by means of a cap portion 20 of the housing which has a radially inwardly extending shoulder 2I engaging the wear ring I9, the cap 20 being threadely secured upon the body portion I of the housing as indicated at 22, so that by screwing down upon the cap 20 any desired pressure may be exerted upon the packing rings 8.

It will be observed that the housing I is provided immediately adjacent the lower end of the gland I5 with an enlargement 23 of its internal bore while the cap member 20 is provided with an internal bore 24 immediately adjacent the upper gland I5 of considerably greater diameter than the greatest diameter of the gland I5. Thus the entire packing unit 6 (including the packing rings 8, tubing 1 and glands I4 and I5) are allowed considerable latitude of lateral movement within the housing and cap so that the packing unit is freely iioating in all lateral directions within the housing.

Moreover, one end of the packing unit 6 is free to float or move laterally independent of the other end of the unit so that either end of the packing unit may shift laterally different amounts and in different directions in order to maintain the axis of the packing unit aligned with a tilted or angular disposition of the polished rod 4.

In Fig. 4 I have illustrated a typical walking beam pumping apparatus as coupled to the pol- .ished rod 4 and which comprises a walking beam A arranged to be oscillated about a pivot B by means of a conventional pitman B. When properly installed, such walking beam A has its outer end C disposed immediately in alignment with the axis of the well bore so that upon oscillation of the walking beam A the polished rod 4 should reciprocate along a direct vertical line which is in turn axially aligned with the housing I of the stuiling box. In order that the arcuate path described by the outer end C of the walking beam will not cause appreciable lateral movement away from this direct vertical line, a horse head D may be provided, over which the cable E coupledto the upper end of the polished rod 4 may pass. Under these circumstances the polished rod 4 will be reciprocated along a direct vertica1 line which will be aligned with the axis of the housing I and the position of the packing unit 6 will be such as is illustrated in Fig. 1. If, however, due to inaccuracy in the construction of the horse head D there is some deviation from the direct vertical movement, the entire packing unit 6 may bodily shift laterally in the housing without imposing any lateral strain upon the packing and the wear on the packing surface will be uniform throughout its circumference.

However, if there has been any misalignment of the outer end C of the walking beam with the axis of the well bore, the path described by the polished rod 4 will be along a direct vertical line but this line will have been shifted or offset laterally from the axis of the housing I, as is illustrated in dotted lines in Fig. 4. When this condition obtains, the entire packing unit 6 will shift to the position shown in Fig. 2, the packing unit being freely oating within the housing I so that it will assume the oiset position and again there will be no lateral load upon the packing rings.

In many wells the actual motion of the polished rod 4 does not follow a true vertical line as depicted in Fig. 4 but describes a path which is disposed at an angle to the vertical or which may include a bending or tilting of the polished rod at different portions of its cycle of movement. For example, as illustrated in Fig. 5, the cable E may be connected directly to the outer end C of the walking beam A without employing the horse head D. The arcuate path described by the outer end C of the walking beam will therefore cause the polished rod 4 to assume different angular positions during different portions of its cycle of operations so that within the stufling box the polished rod is reciprocated along a path of constantly changing angle to the vertical. By employing my stuffing box with the packing unit freely floating at each of its ends, the packing unit may assume constantly changing angular positions, maintaining the packing unit in alignment with the axis of the polished rod, as shown in Fig. 3. To facilitate this angular disposition of the packing unit, I prefer that the packing glands I5 and I 8 be formed with tapering side walls as indicated at I 4a and I5a, respectively, which will permit the sleeve 'I to assume the necessary angular position without requiring tilting of the glands I4 and I5. Under such conditions it will be apparent that the glands I4 and I5 will each slide laterally to whatever extent is required to maintain the packing unit in axial alignment with the polished rod 4 and no lateral load will be imposed upon the packing rings 8.

It will be observed, from an inspection of Figs. l, 2 and 3, that a wear bushing 25 is provided to encircle the polished rod 4 immediately above the steel wear ring I9, the wear bushing 25 being received within a chamber 26 formed in the upper end of the cap or cover` member 2U. The shape of the chamber 26 is such that it provides a radially inwardly extending flange or shoulder 2l, overlying a radially extending flange 28 formed upon the wear bushing 25, but the shape of the chamber 26 is such that all of its lateral diameters considerably exceed the corresponding diameters cf all portions of the wear bushing 25. rIhe lateral space which is therefore provided through which the wear bushing 25 (and the polished rod 4) may shift are maintained, however, slightly less than the lateral space provided in the chamber 3 through which the packing unit may shift. Hence where mis-alignment exceeds the amount which may be compensated for by the shifting of the packing unit, the wear bushing will engage and bear upon the cap 29 so that any wear which occurs, occurs immediately between the wear bushing 25 and the polished rod 4 Where it may be readily noticed and suitable correction in alignment may be made. By forming the wear bushing 25 of cast iron or similar material softer than the polished rod 4, all of the wear which occurs prior to correction will occur on the Wear bushing 25, which bushing is readily replaceable. However, even though such wear does occur, there will be no lateral strains imposed between the packing unit 5 and the polished rod 4 and there will be no loss of seal between these members.

By providing the packing rings 8 freely floating within the shell or tube 1, any bending which may occur in the polished rod during its normal reciprocating motion may be compensated for by the relative lateral shifting of the several packing rings to conform with the bend produced in the polished rod 4. A

Lubrication of the entire stuffing box may be readily accomplished by filling the chamber 3 with suitable oil, grease or other lubricant, which may be introduced through a suitable grease fitting 29 extending into the cover 29. Adequate lubrication of the polished rod may be likewise accomplished by providing a plurality of holes or apertures Sil through the shell 'I which are alignable with the space between the upper and lower flanges of the spacing ring 9 so that lubricant may pass from the chamber 3 through the openings in the shell I and through the apertures I3 provided in the spacing ring 9 to the surface of the polished rod 4.

It will be observed that the bore 3| through the ring 9 is somewhat larger than the diameter of the polished rod 4 so that the interior of the ring 9 forms a lubricant chamber immediately adjacent the surface of the polished rod.

Since the shell 'I is not secured either to the glands I4 and I5 or the packing rings 8 and therefore may assume various vertical positions relative to the spacing ring 9, I prefer to provide a plurality of sets of holes or apertures 30 in the shell 'I arranged in staggered relation above and below the central set of such apertures so that regardless of vertical shifting of the shell 'I at least a number of holes will be disposed adjacent the apertures I3 in the spacing ring 9.

It will be apparent that the stuii'ing box constructed in accordance with the description herein may be readily and economically manufactured since the glands I4 and I5 may be constructed as duplicates of each other and the steel bearing rings I 1 and I9 may be constructed as duplicates. Moreover, it will be noted that the entire packing unit may be readily removed and replaced merely by removing the cover portion 20 of the housing, all of the parts of the packing unit and their associated wear rings being readily removable through the upper end of the chamber 3.

It will therefore be observed that I have provided a stuffing box for polished rods which will automatically compensate for any of the lateral displacements commonly found in oil well pumping apparatus and that, by providing the freely floating packing unit, I insure an adequate packing seal regardless of the cause, character or degree of such lateral displacement.

While I have shown and described the preferred embodiment of my invention, I do not desire to be limited to any of the details of construction shown or described herein, except as defined in the appended claims.

I claim:

1. A stuiiing box comprising a housing through which a reciprocating rod extends, a packing unit surrounding said rod and extending longitudinally along said rod, plane bearing surfaces formed at either end of said packing unit and disposed transversely of the axis of said rod, a chamber formed in said housing having lateral dimensions in excess of the lateral dimensions of said packing unit, plane bearing surfaces formed upon said housing at opposite ends of said chamber to engage and mount said packing unit for free bodily lateral movement within said chamber, a wear bushing surrounding said rod, and a second chamber in said housing for receiving said wear bushing having lateral dimensions exceeding the lateral dimensions of said bushing by an amount less than the dimensions of the first chamber exceeds the dimensions of the packing unit.

2. A stuffing box comprising a housing defining a chamber through which a reciprocating rod extends in the general direction of the longitudinal axis of the chamber; a packing unit surrounding said rod including a pair of glands spaced free of each-other along said rod, a plurality of separate packing rings surrounding said rod and interposed between said glands, each of said glands comprising a bushing having an inner end engageable with said packing rings and an enlarged outer end, a longitudinal rod receiving bore extending through said gland and having a plurality of diameters al1 in excess of the diameter of said rod, progressively increasing from the inner end to the outer end of said gland, the outer end of said gland having a plane bearing surface formed thereon and disposed in a plane perpendicular to the axis of said bore, a sleeve surrounding said packing rings and of greater length than said packing rings to overlie the inner ends of said glands, said glands having an outer surface tapering inwardly as it approaches the outer end of said gland to permit axial misalignment of said sleeve with said gland, and plane bearing surfaces on said housing disposed adjacent each end of said chamber and extending in a plane perpendicular to the axis of said chamber for slidably mounting said glands for free lateral movement independent of each other.

GLYNN H. WILLIAMS.

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