Method Of Tapping A Hole In A Main Through A Fitting

Abstract

A method for opening a flow-way in a main when a main is to be connected to a secondary main or service line. In opening the flow-way in the main, a perforator or tapping tool is utilized, which will progressively form the hole or aperture in the main by upsetting the material of the main outwardly of the same into the through bore of a fitting attached to the main, the upset material acting as a mechanical fastening means for increasing the resistance of a fitting to twist about the axis or center line of the main.

Parent Case Text

This application is a division of our copending application Ser. No. 868,040 filed Oct. 21, 1969, and is entitled to the filing date thereof.

Description

The present invention relates to improvements in a method and for tapping a main when setting up a flow-way from the main to a secondary main or service line.

BACKGROUND OF THE INVENTION

Self-tapping fittings, such as service Tees, nipples, or the like, have been heretofore utilized in connecting a secondary main or service line to a main without the escape of fluid from the main to atmosphere. Such prior arrangements have utilized drilling machines connected to the fittings through which shell cutters or other drills were advanced through a valve and through the fitting to form the hole in a main. Additionally, some fittings have been provided with a through bore that is threaded interiorly, the through bore threadedly receiving the tapping tool which may be advanced by rotation. Such tapping tools had annular cutters for removing the coupon from the main or piercing members for punching a hole through the main. Typical prior art arrangements may be found in the following U.S. patents:

Number Name Date 2,736,335 Webber Feb. 28, 1956 2,839,075 Mueller June 17, 1958 2,852,967 Mueller et al. Sept. 23, 1958 2,895,352 Mueller July 21, 1959 2,950,637 Merrill et al. Aug. 30, 1960 3,264,907 Mueller et al. Aug. 9, 1966 3,302,493 Hulslander et al. Feb. 7, 1967 3,349,792 Larkin Oct. 31, 1967

In the above-mentioned prior art devices, the perforating of the main was accomplished by either removing a coupon from the main, the coupon being retained in the cutter as the cutter was withdrawn from the hole, or by piercing or swaging a hole inwardly of the main when utilizing a solely piercing member. Oftentimes the tapping tool was utilized as a valve means to plug the hole in the main until such time that service is needed.

BRIEF SUMMARY OF THE INVENTION

The present invention involves a method in which a hole or aperture is formed in a main through a bore in a fitting,at least preliminarily secured to the main,by upsetting the material of the main in a generally radial and outward direction into the bore of the fitting. The upset material surrounding the formed hole functions as a mechanical or secondary fastening means between the main and the fitting as it limits the amount the fitting will twist about the center line or axis of the main. In situations where the upset material is substantially in contact with the wall of the through bore, there is no slippage and an immediate lock. On the other hand, in situations where the upset material has a slight clearance with the wall of the through bore, there is a slight slippage before locking would be effected.

Further, the invention contemplates swagging the upset material into tight engagement with the walls of the bore of the fitting so as to assist in locking the fitting to the main against removal in not only a circumferential sense but also in a radial sense. This mechanical locking of the fitting to the main reduces the dependence of clamping straps and minimizes loosing which might take place due to corrosion under the straps.

By utilizing a perforating tool, which has a tapered portion with a thread thereon for swagging and/or cutting the hole, and by controlling the advancement and rotation of the perforating tool, which relation to the lead of the thread on tapered portion, the material being displaced during the progressive forming of the hole can be controlled so as to be upset outwardly of the main into the fitting and against the wall of the bore of the fitting. By upsetting the material outwardly of the main, the material does not extend inwardly of the main so as to interfere with normal flow through the main or restrict the inside diameter of the main. Additionally, the smooth upsetting of the material outwardly of the main into the through bore of the fitting results in a smooth, well-rounded opening, thereby maintaining a minimum pressure drop across the same.

Another aspect of the present invention is to provide a preliminary undersize hole or aperture in the main by cutting a coupon therefrom and then further forming the hole to a predetermined size by upsetting the material around the undersized hole outwardly of the main into the bore of the particular fitting used. This latter mentioned arrangement would be utilized especially where it is desired to provide a relatively large hole in a main, and thus the necessity of cutting an undersized hole first and retaining this coupon and then subsequently progressively increasing the size of the undersize hole by upsetting the material around the undersize hole by swaging such material into the bore of the fitting attached to the main.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross-sectional view of the assembly of the present invention, taken through a main, the assembly utilizing a saddle service Tee type of fitting.

FIG. 2 is an enlarged fragmentary sectional view illustrating the main of FIG. 1 having been perforated with the material from the hole being swaged or upset outwardly of the main into the through bore of the fitting.

FIG. 3 is an enlarged vertical sectional view of the perforating or tapping tool of the present invention.

FIG. 4 is a vertical sectional view similar to FIG. 1, but illustrating a plastic service Tee and a plastic pipe with a modified perforating or tapping tool.

FIG. 5 is an enlarged vertical sectional view of the tapping tool of FIG. 4.

FIG. 6 is an enlarged fragmentary vertical sectional view illustrating the tapping of a hole in a main by the tool shown in FIGS. 4 and 5.

FIG. 7 is a schematic drawing of a typical drilling machine attached to a fitting on a main, the fitting and the main being shown in vertical section with the main having been perforated, or tapped.

FIG. 8 illustrates a further modification of the present invention utilized with a shell cutter for the drilling machine of FIG. 7, the shell cutter functioning to cut a coupon when forming the undersized hole.

FIG. 9 is an enlarged fragmentary sectional view showing the main with the hole formed therein and with the coupon initially removed by the shell cutter of FIG. 8.

FIG. 10 is a still further modification of the present invention, the view being partially schematic and partially in vertical section and illustrating a different type of hand-operated drilling machine; and

FIG. 11 is a vertical sectional view of the modified form of drilling machine shown in FIG. 10, the view illustrating the drilling machine inserting a completion plug into the fitting or service Tee after the hole has been drilled.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein like reference or character numerals represent like or similar parts, there is disclosed in FIGS. 1-3 one embodiment of the present invention for opening a flow way from a main to a service line or pipe. In more detail, there is disclosed a service fitting generally designated at 10 equipped with a tapping tool 11, the service fitting being utilized to connect a main 12 of a fluid pressure system, such as a gas system or the like, to a service line 14, extending to a point of use, such as a dwelling or the like. The main 12 and/or service line 14, as disclosed in this particular environment of the invention, is made of metal but, as will be described later in the specification, the main and the service line may be plastic.

In the particular embodiment disclosed in FIG. 1, the service fitting 10 is shown as a saddle clamp type of fitting having a unitary body member 16 made as a malleable iron casting or as a steel forging, the body member 16 being provided with an integral saddle part 18 having an arcuate surface 20 of a curvature complementary to the curvature of a portion of the external surface of the main 12. Clamping means generally designated at 22 form part of the service fitting 10 and clamp the body member 16 in fluid type connection to the main 12. The clamping means 22 include an arcuate strap-like member 24 with an eye 26 at one end thereof for fitting over a hook portion 30 on the body member 16 and a lug member 32 at the other end thereof, the lug member being provided with an aperture through which bolt means 34 extend. The body member 16 is provided with a similar lug 36, and it will be understood that by tightening the bolt means 34, the service fitting is positioned on the main 12.

While the service fitting 10 is disclosed as a saddle clamp type of service fitting, it will be appreciated such service fitting may be a conventional service Tee welded directly to the main, or otherwise suitably secured thereto, or other types of fittings, some of which are shown in the drawing and which will be described later in the specification.

The body member 16 is provided with a through bore 38 opening to the arcuate surface 20 at its inner end and extending therefrom outwardly. The through bore 38 in the particular arrangement shown in FIGS. 1 and 2 is interiorly threaded at 40, along its entire length for the functions to be described later in the specification. Body member 16 is also provided with a lateral bore 41 opening at the through bore at its inner end, the lateral bore being arranged to communicate with the service line 14 suitably connected to the fitting.

The tapping tool 11 for forming a hole or flow way 43 in the main 12 is shown in FIG. 1 in a retracted position in the through bore 38, after the hole 43 has been formed. In more detail, and also referring to FIG. 3, the tapping tool 11 is provided with a plug-like body member 42, having a first body portion 44 with exterior threads 46 thereon that may be received in the interior threads 40 of the body member 16 of service fitting 10. At the terminal end of the first body portion 44 of tapping tool 11, there is provided a non-circular socket or recess 48, for receiving an Allen wrench or other tool which can rotate the tapping tool on its longitudinal axis A and either advance or retract the same in the threaded through bore 38 of the service fitting 10, depending on the direction of rotation. The body member 42 of the tapping tool is also provided with an intermediate body portion 50, which is frusto-conical and tapers inwardly at an angle of 10.degree. with respect to the longitudinal axis A of the tapping tool. Further, body member 42 is provided with a tapered or conical third body portion 52, which has an external thread 54 of the same hand as the thread 46. The largest diameter of the tapered body portion 54 at the line B is slightly greater than the smallest diameter of the intermediate body portion 50 at the line C, the purpose of which will be described in detail later in the specification. Additionally, the included angle D of the tapered body portion 52 defining the penetrating end of the tapping tool 11 is preferably 30.degree..

It will be noted that the thread 54 on the tapered body portion 52 starts at a slight distance from the point P, as the point P functions as a centering means and keeps the tip P aligned when the hole 43 is started and the thread 54 begins its work. The thread 54 terminates at its upper end, as viewed in FIG. 3, in a buttress thread 56 for the last helix thereof, the purpose of providing such a buttress thread being to make the tapping tool stronger at this area where there could be damage to the thread by the material of the main 12 being upset. Preferably the thread 54, other than where the buttress helix 56 is provided, has a blunt root, as indicated at 58, and a sharp crest as indicated at 60, so that it somewhat resembles the thread of a sheet metal screw. By having a blunt root at 58, rather than a sharp root as in a conventional thread, stress rises, due to the upsetting of material from the main, are reduced and the thread can fully function to swage or move the material when the hole 43 is being formed.

In order to move or swage the material in a predetermined direction from around the hole 43 being formed, the lead or pitch of the helices of the thread 54 on the tapered body portion 52 of the tapping tool 11, differs from the lead or pitch of the helices of the thread 46 on the first body portion 44. In this respect, the thread 54 has a greater lead than the thread 46, and consequently when the tapping tool 11 is positively advanced in the through bore 38 of the service fitting 10 and the tapered body portion 52 begins and is penetrating the wall of the main 12, the material of the main 12 will be swaged or upset outwardly of the main, as indicated at 62 in FIG. 2 up into the through bore 38. In order to obtain the desired movement of the material being upset and swaged from the main 12, it has been found that the ratio between the helices driving thread 46 and the helices of the perforating or swaging thread 54, should be in the order of five to four. In other words, the number of helices per inch of the thread 54 should be 80 percent of the number of helices per inch of the thread 46.

If the tapping tool 11 of FIG. 3 is provided with its tapered body portion 52 and its tapered intermediate portion 50 considerably smaller than its body portion 44, then the upset material will not be swagged radially outwardly into engagement with the wall of through bore 38. However, this arrangement still provides a mechanical lock after there has been slight slippage between the fitting 10 and main 12.

The tapping tool 11 is preferably made of fully hardened steel, at least when it is being used to form a hole in steel or iron pipe. In this respect, it has been found that the tapping tool 11 should be at least 15 Rockwell "C" points harder than the material of the main to be perforated or tapped and with respect to certain steel mains, such tapping tools 11 have been made with a 50 Rockwell "C" hardness number throughout. By providing a fully hardened or for that matter, a case hardened, tapping tool 11, extensive galling of the threads 46 and 54 is prevented during operation.

The operation of the assembly heretofore described is as follows: First, the service fitting 10 is assembled on the main 12 at a location where it is desired to tap the hole 43 into the main for the purpose of connecting the main to the service line 14. Usually the service fitting 10 is provided with a groove 13 on the surface 20 surrounding the lower opening of the through bore 38. An O-ring 15 is provided in the groove 13, the O-ring sealing against the exterior of the main around the location where the hole 43 is to be made. The service line 14 is then connected to the service fitting 10 and the main is ready to be tapped. By use of an Allen wrench or other tool, the tapping tool 11 is rotated in the threads 40 of the through bore 38 in such a manner as to advance the tapered end portion 52 of the tapping tool toward the main. The point P will begin penetration of the main and then the tapered thread 54 begins its work to progressively form the hole 43. In this respect, for each revolution of the tapping tool 11, it is positively advanced a predetermined distance, dependent upon the lead or pitch of the driving thread 46. Since the lead or pitch of the thread 54 is greater than the lead or pitch of the thread 46, the material being displaced by the thread 54 will be directed outwardly of the main 12 and upwardly into the lower end of the through bore 38. The ultimate size of the hole in the main 12 is determined by the maximum diameter B of the tapered thread 54 on the tapered portion 52 of the body member 42.

As soon as the last buttress helix 56 has performed its work there is a relief provided between the tool and the material upset from the hole 43, due to the reduced diameter C of the tapered intermediate portion 50 directly above the buttress helix. Consequently, the operator, when turning the tapping tool 11, will notice a momentary reduction in torque followed by an increase in torque and will be aware that only a few number of turns of the tapping tool 11 need now be made to complete the operation. The tapered intermediate portion 50 will now function as a further swaging surface, as its maximum diameter, as indicated at E, is greater than the maximum diameter of the buttress helix 56 of thread 54. The purpose of the tapered intermediate portion 50 is to force the upset material 62 around the hole 43 radially outwardly of the hole, so that it fills the lowermost helices of the thread 40 of the through bore 38. This positively locks the upset portion 62 to the service fitting 10, so that the upset portion now functions to not only prevent the body member 16 from turning on the axis of the main 10, but also functions to prevent the body member 16 from being easily removed even when the strap-like member 24 of the clamping means 22 is released.

Instead of running the thread 40 all the way to the opening of the through bore 38, with the interior 20 of the saddle 18, recesses, knurling, or grooves may be provided in the lower end of the through bore 38 for receiving the upset material 62 to anchor the same, as is shown in the drawings of other modifications of the invention.

The tapping tool 11 may be coated with a dry film lubricant L such as disclosed in the common assignee's U.S. Pat. No. 3,264,907, issued Aug. 9, 1966 on all of its surfaces, except the swaging surface of the smooth, tapered intermediate portion 50. By leaving the dry film lubricant L off of the intermediate portion 50, the operation of the tapping tool is enhanced as it gives the operator a greater feel when he has completed the penetration portion of the forming of the hole 43, as there is a significant increase in torque when the upset portion 62 is swaged radially outwardly by the surface of the tapered portion 50. Additionally, such an operation is accompanied by a squealing noise giving another clue to the completion of the operation.

Referring now in particular to FIGS. 4-6 inclusive, there is disclosed a modification of the assembly of the present invention which may be utilized for connecting a plastic main 12' to a plastic service line 14'. In this embodiment of the invention, a plastic service fitting or Tee 10' is utilized, the same being somewhat similar to the common assignee's U.S. Pat. No. 2,839,075, issued June 17, 1958, or to the common assignee's U.S. Pat. No. 3,460,553, issued Aug. 12, 1969. In more detail, the plastic service fitting 10' includes a body portion 16' having at its lower end a saddle part 18' provided with an arcuate shaped surface 20' complementary to the exterior surface of the plastic main 12'. A lateral outlet 21 provided with a lateral bore 41' opens to an interiorly threaded through bore 38'. The lateral outlet 21 is arranged to receive the plastic service line 14'. A groove 13' surrounding the opening of the through bore 38' to the surface 20' is provided for receiving an O-ring 15'.

Clamping means 22', such as a pair of hose clamps 24', are arranged to extend about the main 12' and the exterior of the saddle part 18' so as to clamp the service fitting 10' at least temporarily on the plastic main 12'. Sufficient pressure is applied through the hose clamps 24' to enable the O-ring 15' to make fluid type contact between the saddle part 18' and the plastic main 12' during the forming of a solvent weld between the saddle part 18' and the main 12', if such is used.

The through bore 38' is provided with an interior thread 40' which extends from at least adjacent its upper end to a point spaced slightly from its lower end. At its lower end, the through bore 38' is provided with an annular groove, or recess, 45, which functions similarly to the lower helices of the thread 40 in the embodiment of FIGS. 1-3, inclusive. In other words, the groove 45 is arranged to receive the upset material 62', when such material is caused to flow or move radially outwardly of the formed hole or flow way 43' to thereby provide a positive lock or anchor between the main and the service fitting.

A tapping tool 11' somewhat similar to the tapping tool 11 is provided for forming the hole 43'. In more detail, and referring to FIG. 5, the tapping tool 11' in provided with a plug-like body 42' having a first body portion 44' provided with an exterior driving thread 46', which is received in the interior thread 40' of the through bore 38'. The first body portion 44' has a non-circular socket 48' in its outer end, in which an Allen wrench or other tool may be inserted for rotating the tapping tool 11' to advance or retract the same in the bore 38'.

An intermediate body portion 50', which is frusto-conical and tapers inwardly from the first body portion 44' at an angle in the order of 30.degree. with respect to the longitudinal axis A' to a point where it is provided with a short cylindrical portion, is provided for swagging or moving the upset material 62' radially outwardly into the groove 45. The body member 42' is further provided with a tapered frusto-conical third body portion 52', the third body portion tapering inwardly from the lower end of the cylindrical portion of intermediate body portion 50', as viewed in FIG. 5. An external cutting or swaging thread 54' is provided on the exterior of body portion 52'. The included angle of the frusto-conical third body portion 54' is in the order of 30.degree., whereas the thread 54' is coarser than the driving thread 46'. With regard to the threads 46' and 54', the ratio between the helices of the driving thread 46' and the swaging thread 54' is in the order of five to four, so that the lead of the thread 54' which progressively forms the hole 43' is greater than the lead or pitch of the thread 46', and thus will upset material outwardly of the main 12'.

The end of the tapping tool 11' is provided with an annular cutting edge 57 and a longitudinally extending closed bottom bore or recess 59. When the tapping tool 11' initially engages the main 12', the cutting edge 57 cuts from the main 12' a coupon or slug S and forms a preliminary hole in the main 12'. Further, rotation with positive advancement of the tapping tool 11' in the through bore 38' will result in the threads 54' progressively forming the hole 43' and since the lead of the thread 54' is greater than the lead of the thread 46', the material being removed from around the hole will be progressively moved and upset outwardly of the main 12' into the through bore 38' until the last helix of the thread 54' has performed its work.

Plastic material used in plastic mains, as distinguished from metal used in mains, usually has a greater elastic memory. However, it is known that plastic material can be flowed past its elastic memory and this occurs when the hole 43' is being progressively formed by the tapered thread 54' and the material is being upset at 62'. However, in some instances, when the material of the plastic main 12' is moved or swaged radially outwardly by the swaging surface of intermediate body portion 52' into the groove 45, it may have a slight tendency to contract when the tapping tool 11' is withdrawn from the hole 43'. In order to eliminate any such tendency and further, in order to materially increase the resistance of the upset material 62' to shear, a reinforcing metallic ring 61, having an interior shape complementary to the shape of the intermediate portion 50', is loosely fit onto the tapping tool 11' prior to formation of the hole. When the hole 43' has been formed by the thread 54' and the tapping tool 11' is further advanced so that the upset portion 62' can be radially expanded into the groove 45, the material of the upset portion is forced outwardly by the reinforcing ring or sleeve 61 into the groove. When the tapping tool 11' is withdrawn, the ring 61, which has a loose fit on the tool, will remain embedded in the upset material 62' and will form the wall of the hole 43', thus reinforcing the upset material and increasing the amount of force necessary to produce failure from shear. Preferably, the overall longitudinal length of the ring 61 is approximately equal to the wall thickness of the main 12', plus the overall height of the upset material 62'.

As will now be apparent from the above-detailed description of the modification disclosed in FIGS. 4-6, the operation of the assembly is substantially similar to that described with respect to the assembly of FIGS. 1-3, with the exception that a coupon S is first cut from the main 12'. The tapping tool 11' is advanced a predetermined distance for each rotation of the same, and since this advancement differs from the lead of the tapered hole forming thread 54', the material removed will flow upwardly into the bore 38' of the service fitting.

While the cutting tool 11' has been illustrated and described in the use with a plastic service fitting for connecting a plastic main to a plastic service line, it will be understood that such a tool may be used in forming large diameter holes in metal mains. Of course, as previously mentioned, the tapping tool must be harder than the material of the main being perforated and the same is true of the tapping tool 11' regardless of whether it is utilized for perforating a plastic or a metal main.

Referring now in particular to FIGS. 7-9, there is disclosed a further modification of the present invention utilizing the same with a shell cutter operated by a drilling machine, the shell cutter being used in situations where a relatively large hole is to be provided in a relatively large main.

As disclosed in FIG. 7, an existing main 12", in which it is desired to provide a lateral opening for connecting the same to a new supply main or service line (not shown) is provided at the area where the opening is made with a service fitting 10". In this particular instance, the service fitting 10" is a tapping sleeve which includes an upper body member 70 and a lower body member 72 bolted together about the main 12". The upper body member 70 has a branch 71 with a through bore 38" therein and a flange 74 at the upper end of the branch. A flanged end 76 of a conventional gate valve 78 is secured to the flange 74. A shell cutter 80 (FIG. 8) actuated by a drilling machine 84 may pass through the gate valve to cut the opening or hole 43" in the main 12". The gate valve 78 is provided with a body 70 having a flange 82, to which a bonnet 83 for valve is secured.

The drilling machine which is represented diagrammatically at 84 is connected to a flange 90 of the gate valve 78 in the usual manner, the drilling machine having the usual boring bar 86 (FIG. 8). Further, the drilling machine 84, which is of the conventional type, for example the type shown in the common assignee's U.S. Pat. Nos. 2,833,167, issued May 6, 1958; 2,884,808, issued May 5, 1959; and 2,907,229, issued Oct. 6, 1959, is provided with means for either manually or automatically rotating the boring bar 86 and advancing the same a predetermined distance for each revolution. Consequently, a detailed description of the drilling machine 84 will not be given.

The shell cutter 80 is attached to the lower end of the boring bar 86 and in this embodiment of the invention, such cutter defines the tapping tool. Usually a pilot drill 92 extends axially of the shell cutter 80 and projects beyond the cutting teeth 94 of the same. As is well known in the art relating to shell cutters, the shell cutter 80 is rotated and advanced at a predetermined rate by the drilling machine. Its pilot drill is first to engage and bore a hole in the main. Once the hole has been bored in the main and the shell cutter 80 continues to rotate and advance, the teeth 94 of the shell cutter will then cut a coupon S from the main with the coupon being retained on the pilot drill by locking means (not shown). However, in this particular embodiment of the invention, the shell cutter is provided with an outwardly tapered portion 96 above its lower cylindrical portion 98, the tapered portion 96 being provided with an external swaging thread 97 for enlarging the hole preliminarily cut. By providing the swaging thread 97 with a lead or pitch which is greater than the axial travel per revolution of the shell cutter, as determined by the boring bar 86, the tapered thread 97 will progressively pull and upset the material from around the hole into the through bore 38" of the tapping sleeve 70.

A cylindrical swaging surface 100 is provided on the shell cutter 80 immediately above the last and largest helix of the thread 97, this surface having a diameter at least as great as the diameter of the largest helix of the thread 97 so that the material upset, as indicated at 62", is swaged radially outwardly in a similar manner to the previous embodiments. As clearly shown in FIGS. 8 and 9, the through bore 38" of the tapping sleeve is provided at its lower end, when viewing these Figures, with a plurality of annular grooves or recesses 45", which receive the material from the upset portion 62" when the same is swaged radially outwardly of the axis of the hole or opening 43". This mechanically locks the main 12" to the tapping sleeve of the service fitting in a similar manner to that described with the previous embodiments of the invention.

Referring now to FIGS. 10 and 11, there is disclosed a still further modification of the present invention wherein a manually operable drilling machine is utilized to take the place of the driving thread on the tapping tool 11 of the modifications of FIGS. 1-6, inclusive.

In this particular embodiment of the invention, the service fitting 10'" is a saddle clamp type of fitting substantially similar to the service fitting 10, except that the through bore 38"' is not provided with threads for advancing the tapping tool 11'". As clearly shown in FIG. 10, the service fitting 10"' has its body member 16"' exteriorly threaded at 110 for threadedly receiving one end of a gate valve diagrammatically shown at 112. The bore 38"' is interiorly threaded as indicated at 114 adjacent its upper end for reception of a completion plug 116, whereas its lower end of this bore is provided with annular recesses or grooves 45"' capable of receiving material of the upset portion 62'" of hole 43'" formed in main 12'".

A manually operable drilling machine generally designated at 118 is provided with a body member 120 having a through bore 122, the through bore 122 being provided with interior feed or drive thread, as indicated at 124. A feed or drive sleeve 126 extends into the through bore 122 and is provided with an exterior feed or drive thread 128 for cooperating with the thread 124. The portion of the feed sleeve 126 extending out of the body member 120 has a handle 130 fixed thereto, the handle 130 having a threaded bore 132 therein. Body member 120 at its lower end,as viewed in FIGS. 10 and 11, is provided with an external thread 134 arranged to be received in the gate valve 112.

An operating bar 136 extending through the upper end and freely slidable in the feed sleeve 126 is provided with a head 138 at its outer end exteriorly of the feed sleeve. The head 138 has a hole 140 therethrough, through which a thumb-screw 142 can be inserted and threaded into the bore 132 of the handle 130, so as to lock the operating bar 136 both axially and rotatably with respect to the feed sleeve 126. The inner end of the operating bar 136 is externally threaded, as indicated at 144 and is arranged to threadedly receive and support the tapping tool 11"'.

Tapping tool 11'" is identical to tapping tool 11 of FIG. 1 with respect to the tapered body portion 52'", and the tapered thread 54'" on the exterior thereof. Additionally, the intermediate body portion 50"' is identical to the intermediate portion 50 of the tapping tool 11 in that it provides a recess after work is completed by the thread 54'" and functions as a swaging surface.

When it is desired to operate the assembly disclosed in FIG. 10, the tapping tool 11'" is threaded onto the threaded end 144 of the operating bar 136 and the operating bar is then moved to a position where the tapping tool 11'" is completely retracted within the body member 120. The body member 120 is assembled on the gate valve 112 and once this has been done, the operating bar 136, once the valve has been opened, can be moved to the position where the tapping tool passes through the gate valve 112 and through the bore 38'" to a point where the head 138 is flush against the handle 130 of the feed sleeve 126. The thumb-screw 142 is then inserted through the head 138 and threaded into the handle 130 to lock these two elements together. By rotating the handle 130, the feed sleeve 126 rotates and advances in the thread 124 of the body member 120. This also causes rotation of the tapping tool 11'" and a predetermined advancement of each revolution thereof. Since the threads 124 and 128 of the body member 120 and the feed sleeve 126, respectively, have less of a lead than the tapered thread 54'" on the tapping tool 11'", the hole 43'", being progressively formed, will have the material removed therefrom upset, as indicated at 62'". Once the thread 54'" has completed its work, then the swaging surface of the intermediate portion 50"' will urge the upset portion radially outwardly of the axis of the bore 38'" into the recesses or grooves 45'". When this has been accomplished, the hole 43'" is complete and the reverse procedure is accomplished to withdraw the tapping tool 11"' through the gate valve 112.

The gate valve 112 is then closed and the body member 120 is removed therefrom, so that the tapping tool 11'" can be unthreaded from the end 144 of the operating bar. After this has been accomplished, then the completion plug 116 is inserted onto the threaded end 144 of the operating bar 136 and the body member 120 is reassembled onto the gate valve 112, so that the insertion plug can be advanced through the gate valve when opened and threaded into the interiorly threaded upper end 114 of the bore 38'", as shown in FIG. 11. After the completion plug 116 has been threaded into the upper end of bore 38'", then the rotation of the operating bar 136 in an opposite direction will cause it to separate from the completion plug 116. The gate valve 112 may then be removed from the fitting 10'" and replaced by a closure (not shown).

The terminology used throughout the specification is for the purpose of description and not limitation, the scope of the invention being defined in the claims.

Claims

What is claimed is:

1. A method of tapping a hole in a main through a through bore in a fitting at least temporarily secured to the main, the fitting having a tapping tool with a threaded tapered portion for progressively forming the hole, the steps comprising: advancing and rotating the tapping tool toward and into engagement with the advancement per each revolution of the same being controlled to be less than the lead of the thread on the threaded tapered portion, causing the material around the hole being formed in the main to be swaged outwardly of the main into the through bore of the fitting to thereby eliminate obstruction within the main and to thereby provide a mechanical fastening between the main and the fitting to increase resistance of the fitting from twisting about the axis of the main.

2. A method as claimed in claim 1 including swaging the material upset by the threaded portion of the tool in a generally radial outward direction into engagement with the wall of the through bore in the fitting.

3. A method as claimed in claim 2, including the step of preliminarily cutting a hole in the main of a smaller diameter than a predetermined desired diameter, and then upsetting the material around the hole in the main to enlarge the hole to the predetermined diameter, the material being upset radially outwardly of the axis of the main into the through bore of the fitting.

4. A method as claimed in claim 3, including reinforcing the interior of the upset material defining the finished hole.