US2313308A

US2313308A - Casing head

Info

Publication number: US2313308A
Application number: US373277A
Authority: US
Inventors: Allen Herbert
Original assignee: Cameron Iron Works Inc
Current assignee: Cooper Industries LLC
Priority date: 1941-01-06
Filing date: 1941-01-06
Publication date: 1943-03-09
Anticipated expiration: 1960-03-09

Description

H. ALLEN March 1943" SING E 2 Sheets-Sheet 1 Filed Jan. 1941 I Him March 9, 1943. 1-1. ALLE '2,313,308

CASING HEAD Fiied Jan. 6, 1941 2 Sheets-Sheet 2 INVENTOR M- fi Patented Mar.

CASING HEAD Herbert Allen, Houston, Tex, assignor to Gaineron Iron Works, Houston, Tex., a corporation of Texas Ap ication January 6, 1941, Serial No. 373,277 8iClalms. (01. 285-30) This invention relates to casing heads and in particular to methods and apparatus for securing inner well casings to casing heads. Y

Heretofore, in completing wells, 9. seal has been provided between the inner well casing and the casing head by securing said casing to a separate flange which is placed on top of the casing head. In practice, the separate flange is usually welded directly to the casing, but it has been found that this welded oint has a tendency to break. This breakage is due to the stresses set up during the expansion and contraction of the metals of the casing, the welded joint and the flange in the course of heating and cooling during the welding operation. This difliculty is even greater when very heavy casing. such as is now necessary under certain conditions, is used. The present invention relates to methods of welding and flange constructions for preventing the failures heretofore encountered in these welded connections.

An object of this invention is to provide a flange which may be welded to a well casing without the usual tendency of the joint to be broken after the welding operation has been completed.

Another object of this invention is to provide a method of welding a flange to a casing passing therethrough which will eliminate the stresses due to heating and cooling which occur in th conventional welded joint.

A further object of this invention is to provide a flange capable of accommodating the expansion due to heating and cooling of the welded joint and thus preventing the occurrence of stresses which might cause fracture of the joint.

In order to facilitate the understanding and utilization of the present invention, reference is made to the accompanying drawings in which:

Fig. l is a fragmentary vertical sectional view of a casing and a separate flange mounted there- Fig. 2 is a View similar to Fig. 1 showing a modified form of the invention.

Fig. 3 is an enlarged fragmentary vertical sectional view illustrating the formation of a welded joint according to the present invention.

Fig. 4 is a vertical sectional view illustrating the mounting of the casing and flange in association with a. casing head.

Referring to Fig. 4 of the drawings, there is shown a casing head I having threads 2 in its lower portion for receiving a surface string of casing. The casing head I has a substantially bowl-shaped opening 3 through which extends the inner well casing As shown in the drawings,

the well casing 4 is supported bya plurality of slips 5 which are wedgedly mounted between the bowl-shaped portion 3 of the casing head and 'thecasing 4. "A flange 6 is provided on the upper portion of the casing head I and is adapted to have mounted thereon a flange I which is welded to the inner casing I. Registering annular grooves are provided on the upper surface of flange 6 and in the lower surface of flange 1 to receive a sealing gasket 8. Flange I is adapted to be drawn down onto the flange 6 by means of bolts or other suitable devices to seal the joint between flanges 6 and i.

The present invention resides primarily in the construction of the flange I and the manner in which said flange is secured by welding to the inner casing 6. As shown in Fig. l of the drawings, the upper surface of flange T is provided with an annular slit or groove 9 which is concentric with the opening in the flange through which the casing 6 passes. The slit 9 is closely spaced to the opening in the flange 1 so that a tubular upstanding portion or flange I0 is provided about the casing 4. In practice the thickness of the upstanding portion Ill is such that said portion ill is resilient compared to the flange I proper. As shown in the drawings, the inner upper edge of the upstanding tubular portion I0 is chamfered to receive a bead ll of weld metal to join the upper inner edge of th portion I ll to the casing 4. It has been found that when so welding the flange 1 to the casing 4. the tendency for the welded joint to break is considerably reduced compared to a construction wherein a solid flange is welded to a casing.

A modified form of th present invention'is shown in Fig. 2. In this form of invention, the flange 1 is not directly welded to the casing but is welded to a short piece of flexible tubing I! which in turn is welded to the casing 4. The flange 1 shown in Fig. 2 is identical to that described in connection with Fig. 1. The joint between the lower end of the pipe or tubing 12 and the upper edge of the upstanding portion H! of the flange I may expand and shrink without breaking by reason of the resilient nature of the upstanding portion l0 and of the lower end of the section of pipe I2. Since the section of pipe or tubing I2 is resilient, the joint between the upper end thereof and the casing 4 may be subjected to a reasonable amount of expansion and con-. traction without breaking. In this form of invention the flexibility of the short length of pipe I! is added to that of the small upstanding portion ID of the flange I so that the expansion and contraction of the casing 4 or the weld to said casing will in no way affect the flange 1.

In welding a flange onto the inner casing, it is customary to lay down a single bead of weld metal joining the flange and the casing. When this relatively large head of weld metal cools, there is a tendency for considerable shrinkage of the weld. In accordance with the present invention, it has been found that instead of depositing a single large bead of weld metal that the shrinkage is considerably reduced by depositing relatively small beads of weld metal one after another and one on top of each other. This method of welding is illustrated in Figs. 3 and 4 of the drawings. As may be more easily seen from Fig. 3 in carrying out the above referred to method of welding, a thin small bead I5 of weld metal is deposited about the circumference of the inner casing 4. After this head has been deposited and cooled, a second bead I6 is deposited to join the bead l5 to the flange I.

If it is found that the space between the flange l and casing 4 is too large to. be filled by two layers or beads of weld metal without causing such shrinkage as to endanger the joint, 3 or 4 or more beads of weld metal may be used in making the complete weld. A weld connection formed in this manner will not be subject to the shrinkage stresses inherent in a joint formed of a single large bead of weld metal. The reason for this is that when the first thin layer or bead I5 is placed around the pipe of casing 4, it becomes relatively cool and does it's shrinking before the next layer or bead I6 is deposited. Thus, a part of the metal forming the welded joint is allowed to shrink before the actual welded connection with the flange is made by the final deposit of the bead IS. The only shrinkage which occurs in the joint after the connection with the flange is that which takes place in the relatively small bead l6 which in the twobead weld will be approximately one-half as much as would be the case if a single large bead were employed. It has been found in practice that the strength of the metal is suficient to withstand the shrinkage of the relatively small bead I6. 1

When the above described multi-bead method of welding is employed in conjunction with a flange 1 having the resilient upstanding tubular portion ID, the tendency of breakage of the joint is even less.

In order to test the welded joints for leakage, the flange 1 employed in the several forms of the present invention is provided with an annular groove H in the wall. of the opening through which the casing 4 extends. Said groove l1 communicates with a threaded bore I8 which extends radially from said groove to the outer periphery of the flange 1. A check valve I9 is provided in the inner end of the bore l8 and a threaded plu or plunger 20 is mounted within the bore and adapted to be screwed therein to force plastic packing material into groove 11 to provide a seal between the flange I and the casing 4. A second annular groove 2| is provided in the wall of the opening of the flange I through which the-casing 4 passes between the groove l1 and the weld ll (Fig. 1). A radially extending duct 22 communicates with the groove 2| for the introduction of a fluid under pressure into the groove 2|. If a fluid under pressure is introduced into the groove 2! through the duct 22 and the pressure does not drop, then it may be assumed that the seal between the flange I and the casing 4 provided by the welded joint does not leak. If there is some leakage, then the plunger 20 is moved into the bore l8 to increase the pressure on the packing material in groove II. If after this operation a leakage is still indicated, then it may be assumed that it occurs in the welded joint and steps should be taken tocorrect the same.

Fromthe foregoing description, it will be realized that the present invention provides certain methods and constructions hereinafter claimed for welding well casing to flanges so as to avoid the dangers and disadvantages of the welded joints heretofore employed.

Having described my invention, I claim:

1. In a casing head construction, a casing, a flange having an opening through which the casing extends, a bead of weld metal surrounding and joined to said casing, and another bead of weld metal surrounding the first mentioned bead and joining said first mentioned bead to the flange.

2. In a casing head construction, a casing, a

flange having an opening through which the casing extends, and a plurality of concentric joined layers of weld metal interposed in series between and together joining the casing to the flange.

3. A flange for supporting well casing having an opening therethrough for receiving said casing, an annular groove in the surface of said flange concentric with said opening to form a relatively thin and flexible upstanding annular part surrounding the casing, and a plurality of concentric joined layers of weld metal interposed in series between and together joining the casing to the free edge of said upstanding part.

4. A flange for supporting well casing having an opening therethrough for receiving said casin an annular groove in the surface of said flange concentric with said opening to form a relatively thin and flexible upstanding annular part surrounding the casing, weld metal joining the free edge of said upstanding part to the casing, said flange having an annular groove in the wall of the opening thereof below said weld metal to receive packing material, a duct extending radially from said packing receiving groove to the outer periphery of said flange for forcing packing material into said packing receiving groove, and means for introducing a fluid under pressure into said opening between the weld metal and the packing receiving groove to test the sealing emciency of the weld.

5. A flange for supporting well casing having an opening therethrough for receiving said casing, and a short length of tubing of larger external diameter than the internal diameter of said opening, said tubing surounding said casing and joined at one end to the casing and at its other end to the flange.

6. A flange for supporting well casing having an opening therethrough for receiving said casing, a short length of tubing of larger external diameter than the internal diameter of said opening, said tubing surrounding said casing, weld metal joining one end of the tubing to the cas: ing, and other weld metal joining the other end of the tubing to the flange.

. '7. A flange for supporting well casing having an opening therethrough for rece ving said casing, an annular groove in the surface of said flange concentric with said opening to form a relatively thin and flexible upstanding annular part surrounding the casing, a short length of tubing of larger external diameter than the internal diameter of said opening, said tubing surrounding said casing, weld metal joining one end of the tubing to the casing, and other weld metal joining the other end of the tubing to the free end of the upstanding annular part of the flange.

8. A flange for supporting Well casing having an opening therethrough for receiving said casing, a short length of tubing surrounding said casing, weld metal joining one end of the tubing to the casing, other weld metal joining the other end of the tubing to the flange, said flange having an annular groove in the wall of the opening of said flange below all of said weld metal to receive packing material, a duct extending radially from said packing receiving groove to the outer periphery of said flange for forcing packing material into said packing receiving groove, and means for introducing a fluid under pressure into said opening between the weld metal and the packing receiving groove to test the sealing efliciency of the weld.

HERBERT ALLEN.