Pipe connection

7_S 1942»

J, J, KANE ET AL

PIPE CONNECTION

Filed Jan. 3, 1939

<img file="US2289271A_D0001.tif" />

ATTORNEYS

Patented July 7, 1942

2,289,271

UNITED STATES PATENT OFFICE

2,289,271

PIPE CONNECTION Joseph J. Kane, Galveston, and Raympnd A. Chambers, Houston, Tex., assignor to Kane Boiler Works, Incorporated, Galveston, Tex., a corporation of Texas

Application January 3, 1939, Serial No. 249,094

Claim. (CL 285—146)

The invention relates to an improvement in the connection of pipe sections and particularly where a string of pipe is to be connected and lowered into a .well bore. Considerable difficulty is encountered in lowering a string of casing into a well bore because the diameter of the pipe quite closely approximates the diameter of the well bore and in practically all instances the well bore is crooked. It is well understood that in the drilling of wells by the rotary method of drilling . that the continuous rotation of the drill bit in a clockwise direction causes the well bore to assume a helical configuration and that in addition to this curvature if the bit strikes a boulder or inclined formation it is not uncommon for a sharp deviation to occur. Some of these deviations will be as great as 10°, 15° or 20°, and will veer oft from the general direction of the well bore at quite a sharp angle. Also the casing has frequently to be employed in wells where side tracking has been necessary, thus causing abrupt deviations from a straight line.

In the setting of a string of well casing it is therefore a common practice to lower the string of pipe into the well until it will not sink by gravity any further and to then raise and drop the entire string of pipe sharply in an attempt to ram or spud the pipe beyond the obstacle in the well bore. This operation is known as spudding the pipe, and in many instances the string of pipe will be spudded for a period of several hours in attempting to force the pipe down to the proper elevation in the well bore.

It is needless to say that enormous stresses are set up in the pipe when an entire string of several thousand feet in length is dropped sharply. The stress transfer must be from one joint of pipe to the next, regardless of whether it is a tensile or compressive stress, and it is with the object of providing a pipe joint which is particularly adapted to withstand such stresses that the present invention has been devised.

In oil fields where extremely high gas pressures are encountered, the usual threaded cou- _ pitngs for casing do not provide a sufficient seal 45 strong and fluid-tight connection, and leakage frequently develops around the ^T « ««^nDr «· threads. Casing for such wells must be made of extremely strong steel and in some cases this steel is stronger than any weld which can be made on it. It is an object of this invention to 50 prevent leakage even under excessively high pressures by the provision of a joint in which the necessary supporting strength is inherent in the thrpadR and the gas seal is made certain by a ------------ .. _ band of welding material deposited around the 55 end of the next upper section. It is customary to top circumference of the bell end of one section and against the spigot end of the mating section.

It is one of the objects of the invention to provide a pipe joint for welded pipe so that the pipe sections may be welded end to end as they are lowered into the well in such a manner that the joints will withstand the compressive forces of a spudding operation and also withstand the tensile stresses due to the weight of a long string of pipe.

A still further object of the Invention is to provide a pipe joint which can be welded together as the string of pipe is lowered into the well and which will develop at the joint a strength at least equal to the strength of the pipe.

Another object is to provide a well pipe joint made up by threading and welding so that the joint will be capable of withstanding any stresses which the pipe itself will withstand.

It is also an object of the invention to provide a welded joint for upset pipe so that the size and strength of the band of welding material may be larger to obtain at least the strength of the pipe 25 in the weld.

It is also desired to provide a casing joint which is easily and quickly connected and which is tightly sealed at a plurality of areas.

Fig. 1 Is a central longitudinal section through 30 a well casing connected in accordance with our invention.

Fig. 2 is a broken detail of a pipe joint employing a slight modification of the structure shown inFig. 1.

Fig. 3 is a sectional detail showing a further modification of the invention.

This is a continuation in part of our co-pending application Serial No. 15,202, filed April 8, 1935.

Tn the drawing is illustrated a form of well casing which is ordinarily made of a good quality of steel, the sections being connected together so as to form a fluid tight connection which may be connected quickly together and still form a

In forming the casing, a section such as is shown at 1 in Fig. 1 is formed with the lower end threaded at 2. This is the male end of the pipe and is ordinarily termed the spigot end.

t The other end of the section is made of somewhat larger diameter by forming a socket 8 therein and is ordinarily termed the bell end. The lower portion of this socket or box is threaded at · to engage with the lower threaded

2,289,271

Insert the sections into the well with, the spigot end downwardly fitting within the bell end of the next lower section which is projecting upwardly.

It is necessary that the casing be inserted into the well as rapidly as possible. The walls of the well are liable to cave when left for a period of time and the casing should be inserted as rapidly as possible. In my prior Patent No. 1,966,248, dated January 10, 1934, I have illustrated a casing of this character adapted to be quickly coupled together. However, the present invention is also formed for quick connection but with the object of forming a stronger joint and more effective seaL To accomplish this the lower end of the casing sections, that is, the spigot end, is threaded for a short distance so that when the spigot end is inserted into the bell of the next lower section only a very few rotations of the section is necessary to screw the spigot end into the bell end, as shown at 4.

Above the threaded portion of the bell is a plain unthreaded area, which is preferably loose enough to prevent such heating of the spigot as will cause gas to form along the threads where lubricant is placed, between the spigot and the belL This space is shown somewhat exaggerated at 5. This spacing also allows the weld to be cut off for salvage purposes. In the form of the invention shown in Fig. 1 the upper end of the bell is shown as squared off to form a shoulder at 8, against which the welding material 7 may be placed.

In placing the bond of welding material 7 in _ ________ _____ position upon the joint after the ends have been 35 pipe is filled with liquid, as is soinetimes*done screwed together, the ends of the pipe are heat- ----------- . . . .

ed by the application of the arc or the torch to the welding rod, and the area at @ and adjacent area of the pipe end are heated suffi- . . ..

ciently so that they are wetted with the molten 40 material which is available in the making of welding rods. It is, therefore, difficult to obtain a welded joint of the same area as the cross section of the pipe which would develop the full strength of the pipe in tension. A higher facto transfer large compressive stresses without subjecting the weld metal 7 to such stresses.

In Fig. 3 is shown a threaded connection similar to that in Fig. 1. In this embodiment, however, the spigot end of the pipe is also upset, as shown at SO, so that a greater strength at the joint is provided where a great tension and compression in the pipe is necessary. In all of these types of joints it is possible to provide an inwardly beveled shoulder β i on the pipe, as shown in Fig. 3, so that the bond of welding material will have a larger area of contact with both sections of pipe, thus making it possible to get a still stronger weld. Whether the beveled shoulder ί i of Fig. 3 or the radial shoulder S of Figs. 1 and 2 be used the additional thickness of the bell provides a larger surface upon which the welding material 7 can be deposited and in this manner a strong weld bond is provided to cooperate with the threaded connection 2 or 3a to effect the superior joint of the invention. The Fig. 3 embodiment of the invention is adopted where the casing is subjected to higher strains and rougher usage than is ordinary with well casing.

It has been found in actual practice that pipe sections may be welded together on the location as they are lowered into the well bore and are then superior to the threaded coupling sections in ordinary use at the present time. Welded casing is much more economical and can be lowered into position much quicker than the threaded end pipe.

With the drilling of deeper wells longer strings of casing are necessary and when the string of an enormous load is placed on the pipe joints. With present day practices the unit strength of the steel available for making pipe sections is somewhat in excess of the unit strength of the material and when the bond Ί of welding material is deposited in position, as shown, there is a slight alloy of the steel of the weld with that of the adjacent areas of the pipe sections so _____„_______ that a fluid tight seal is made. Also, it will be' 45 t°r of safety may be provided by threading the understood that the union of the bond of welding material with the adjacent pipe areas is a strong one so that there is in effect an integral connection between the bell and the spigot of the pipe ends.

In Fig. 2 a slightly different form of thread is employed and a square thread 3a is shown, which is somewhat stronger than the sharp crested thread shown in the Fig. 1 embodiment and is enabled to be threaded together by a comparatively few turns of the pipe section. The bond 7 of the welding material is laid down in the same way as in the previous embodiment. It will be noted in the use of this type of connection that the threaded area will withstand a stronger end thrust, such as may be necessary in forcing the casing downwardly into the well where the well is deflected from the vertical so that the well bore is not straight.

Attention is also directed to the fact that the invention as disclosed in this figure of the drawing, and in Fig. 3 to which further description will be directed, comprehends the use of a bell end which is enlarged preferably by upsetting so that a thicker walled bell end is obtained. The thickness of the bell end is therefore materially greater than is the central or pipe portion i. The shoulder 8 in the bell is engaged by the end face 9 on the spigot. This feature enables the joint connection at the lower end of the casing section. Little time is thereby consumed but firmer connection is obviously provided.

Furthermore, in order to provide against 50 shrinkage of the metal at the joints in cooling after the bond- of welding· material has been laid on, it is possible to exert an upward pull upon the pipe section after it has been screwed into the bell of the lower section so that the metal of the pipe will be under tension during the time the welding job is performed. Then, when the strain upon the pipe is released any shrinking in the pipe at the joint will be so slight as to be of no detrimental effect upon the joint.

An advantage which is obtained by unsetting the end of the pipe is that a greater area of metal is present into which the heat of the welding may be dissipated without detrimental effect upon the metal. It will be understood that after ₆₅ the connection has been completed the sections are lowered immediately into the well which is full of mud and quenching action is obtained up the heated metal. It is, therefore, not ripsirable to heat up the steel of the pipe sections to 70 a point where they will be materially hardened by quenching.