A METHOD FOR LOAD TESTING OF CATHEADS

FIELD OF INVENTION
[0001] The present disclosure, in general, relates to a method for load testing of catheads. More particularly, the present invention relates to oil field equipment. Further, the present invention provides a simple method of load testing of makeup and breakout catheads.
BACKGROUND OF INVENTION
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] A draw works is an oil field equipment used in oil rig which is the main source of power for hoisting and rotating equipment.
[0004] The draw works is one of most important equipment’s on a drilling rig. The draw works transfers the hoisting power. The primary function of the draw works is to reel out and reel in the drilling line, a large diameter wire rope, in a controlled fashion.
[0005] The drilling operation make up (tightening) and break out (loosening) of drill pipe is of continue process. Make up and break out operation require very high Torque which is not possible manually. The draw works power is used to carry out these make up and break out operations in a drilling rig through a catheads and manual tong. The catheads apply the pulling force (Torque) on the hand tang connections.
[0006] The catheads are mounted on either side of sandreel (cathead) shaft which is rotating continuously geared through the main drum as shown in Figure-1..
[0007] The cathead is having following important components.
• Main sleeve assembly
• Drum assembly
• Diaphragm assembly
[0008] The sleeve assembly (1) and the drum assembly (2) are having friction lining (3) discs as shown in Fig. 2. The diaphragm (4) assembly is a tube and it can be inflated by air and it is in between the sleeve assembly and the drum assembly. The cathead does kind of torque transfer through friction plate drive mechanism which it is operated by air supply.
[0009] The sleeve assembly (1) is bolted on to the sandreel shaft which is continuously rotating along with sand reel shaft whereas a drum assembly (2) is stationary during normal condition.
[0010] During the operation of make up or break out of drill pipe, one end of wire rope is wrapped around the drum assembly (2) and other end is connected to the manual tong which in turn applies the torque on pipe screwed joints for makeup and break out.
[0011] Whenever the make up or break out of drill pipe is required, the diaphragm (4) is inflated by air supply. The inflated diaphragm will push the drum assembly (2) towards the sleeve assembly (1) such that the friction plates on both sides of drum assembly (2) and sleeve assembly (1) are engaged and the drum assembly (2) will be rotating along with the sleeve assembly (1). The wire rope, already fixed onto the drum assembly (2), is wrapped around the drum assembly (2) and due to rotation of drum assembly (2) it will pull the manual tong (22) and the torque applied at the pipe joint (23) as shown in Figure-5
[0012] The catheads (24) are having various rated pull (or torque) ratings with various air pressures.
[0013] The cathead (24) will be supplying its rated torque (or pull) thru by engaging the Friction discs, if the pull exceeds the rated pull, friction discs slips and no rotary motion transfers to the drum assembly.
[0014] Chinese patent CN204253682U discloses retarder steel-belt type braking device used for oil-field oil pumper. The utility model discloses a kind of retarder steel-belt type braking device used for oil-field oil pumper, comprise a brake band, described brake band is integrated type, its inside is provided with brake wheel and brake strap successively, brake band and brake strap by rivet riveting and together with, brake strap employing resin rubber non-asbestos friction plate.The beneficial effects of the utility model are, Novel steel band brake is owing to adopting monolithic construction and having certain amount of deformation, brake strap adopts resin rubber non-asbestos friction plate, brake strap and brake wheel in braking state time its area of contact can reach 90 more than %, better can realize the effect of braking, can also reduce the labor intensity of operator in addition, weight itself is also lighter than watt formula braking device of stopping many, brings great convenience to installation personnel. The steel belt type brake device of speed reducer for oil field pumping unit. A steel belt type brake device of a speed reducer for an oil field pumping.
[0015] However, the prior art describes only about steel belt type brake device but not talks about load testing of brake band
[0016] Therefore, there is a requirement to develop a method for load testing of catheads. Hence, the present invention has been introduced.

OBJECTS OF THE INVENTION
[0017] Some of the objects of the present disclosure, which at least one embodiment herein satisfy, are listed herein below.
[0018] It is a general or primary object of the present disclosure to provide a method for load testing of catheads in shop floor.
[0019] It is another object of the present disclosure to provide a method for load testing of catheads, which is simple.
[0020] It is yet another object of the present disclosure to provide a method for load testing of catheads, which serves the purpose efficiently.
[0021] These and other objects and advantages of the present disclosure will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present disclosure is illustrated.
SUMMARY OF THE INVENTION
[0022] This summary is provided to introduce concepts related to a method for load testing of catheads. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0023] According to this invention, there is provided a method for load testing of catheads comprising providing a mounting fixture for load testing of a catheads. Fixing the bottom of the fixture onto a T-slot of test bed for load testing of the catheads. Fixing the cathead on to the fixture with peripheral bolts of a sleeve assembly, the sleeve assembly is at stationary condition while a drum assembly free to rotate as friction discs are not engaged. Wrapping one end of wire onto the drum shaft and other end of the drum shaft is connected to an overhead crane. Connecting a load cell in between a wire rope and overhead crane for monitoring the load. Supplying an air to the diaphragm and an air pressure monitored with the help of a pressure gauge.
[0024] As the diaphragm is inflated with an air supply, the drum assembly is pushed towards sleeve assembly and the friction discs comes in touch with each other and the drum assembly also is in stationary position.
[0025] The load is applied slowly through the overhead crane, till the drum assembly slips from the sleeve assembly and pull load is noted.
[0026] The pull where the drum assembly is slipped from sleeve assembly is the rated pull of cathead at that air pressure.
[0027] If the pull force is not meeting the rated pull load, then the catheads are dismantled and checked for assembly, friction linings, diaphragm, and springs.
[0028] The catheads are again tested at the rated load till the desired parameters are achieved.
[0029] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0030] The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and methods that are consistent with the subject matter as claimed herein, wherein:
[0031] FIG. 1 shows an arrangement of catheads in draw works, in accordance with an embodiment of the present disclosure;
[0032] Fig. 2 shows a schematic of cathead assembly, in accordance with an embodiment of the present disclosure;
[0033] Fig. 3 shows a cathead mounted on fixture for load testing, in accordance with an embodiment of the present disclosure;
[0034] Fig. 4 shows a cathead under load testing, in accordance with an embodiment of the present disclosure; and
[0035] Fig. 5 shows a schematic of pull (torque) transfer through cathead to manual tong, in accordance with an embodiment of the present disclosure; and
[0036] Fig. 6 shows a flow chart of method for load testing of catheads, in accordance with an embodiment of the present disclosure.
[0037] The figures depict embodiments of the present subject matter for illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAIL DESCRIPTION OF INVENTION WITH REFERENCE TO THE DRAWINGS OF THE PREFERRED EMBODIMENTS
[0038] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to con all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0039] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0040] The catheads are supplied along with the load testing certificates. Sometimes, catheads are not taking their rated load in customer site due to various reasons. In order to avoid issues at site, it is decided to carry out the load test of catheads again in the workshop before assembly of catheads into draw works.
[0041] The draw works is the heart of the drilling rig. It is the capacity of the draw works that characterizes a rig and indicates the depth rating for the boreholes that can be drilled.
[0042] Makeup and Breakout torque is still very commonly applied with multiple-jaw tongs. The backup tong is secured to a stationary point by line or chain. The other is connected to a head that is rotated by the cathead transmission. The pulling force exerted by the cathead provides torque on the tubular by means of the lever arm corresponding to the length of the tong. Two crew men are required to pace and remove these tongs.
[0043] Spinning cathead (14): The first phase in screwing pipe together, i.e. putting the two ends together until the box and pin shoulders meet, should be performed as quickly as possible. One end of the chain is held tight by a crew man. The other end rolls up on the spinning cathead (14) controlled by the driller. The winch effect rotates the pipe as the chain spins.
[0044] Breakout cathead (13): A device attached to the cat shaft (15) of the draw works that is used as a power source for unscrewing drill pipe- usually located opposite the driller's side of the draw works (16).
[0045] The spinning chain method is quick but requires a lot of skill and good coordination. It is hazardous for the crew man who is in charge of pulling and holding the laps of chain around the pipe. A lot of skill is required to operate the equipment. A unique load test facility is developed in order to carry out the load testing of catheads at rated pull before supplying the same to customer.
[0046] In order to load testing of catheads, simple methodology has been developed.
[0047] In house test facility developed for the load testing the catheads before assembly into a draw works (16).
[0048] Now reference may be made to the accompanying Figures.
[0049] A mounting fixture (8) is provided for the load testing purpose. For the load testing of catheads, the bottom of the fixture (8) is fixed onto the T-slot of test bed.
[0050] The cathead is fixed on to the fixture (8) with peripheral bolts of sleeve assembly (1). The sleeve assembly (1) is at stationary condition (fixed) while a drum assembly (2) is free to rotate as friction discs are not engaged (i.e. diaphragm (4) is not inflated as there is no air supply)
[0051] For carrying out load test, one end of wire is wrapped onto a drum shaft and other end is connected to overhead crane (10). In between wire rope (7) and overhead crane (10), load cell is connected for monitoring the load. Now, air is supplied to the diaphragm (4) and air pressure is monitored with the help of a pressure gauge.
[0052] As the diaphragm (4) is inflated with the air supply, the drum assembly (2) is pushed towards the sleeve assembly (1) and the friction discs come in touch with each other and now the drum assembly (2) also is in stationary position (Not rotating). Now slowly the load is applied thru overhead crane (10), till the drum assembly (2) slips from sleeve assembly (1) and pull load is noted. The pull where the drum assembly (2) is slipped from sleeve assembly (1) is the rated pull of cathead at that air pressure. Same way the testing is carried out for different supply air pressures and results are compared with vendor supplied test results.
[0053] If the pull force is not meeting the rated pull load, then the catheads are dismantled and checked for assembly, friction linings (3), diaphragm (4), and springs and again the catheads are tested at rated load till the desired parameters are achieved.
[0054] ADVANTAGES OF CATHEAD TEST FACILITY:
• Simple and very fast method to know the load carrying capacity of catheads
• In house testing saves lot of time in site (no site complaints from customer). Lot of production time saves to customer
• No rotating components are involved
• No special equipment are required for testing.
[0055] TEST RESULT:
SPINNING CATHEAD (S.No. XK-18-1164330)
S.no. Air pressure applied (psi) to Diaphragm Required Straight line pull (customer Requirement at site) Straight line Pull as per vendor test certificate Straight line pull (Tested with BHEL developed test set up)
1 80 8,000 lbs 8250 lbs 8235 lbs
2 100 10,000 lbs 10,250 lbs 10,245 lbs
3 120 12,500 lbs 12,500 lbs 12,505 lbs

[0056] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particulars claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances, where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B”.
[0057] The above description does not provide specific details of manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art are capable of choosing suitable manufacturing and design details.
[0058] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
[0059] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
[0060] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

We Claim:

1. A method for load testing of catheads comprising:
- providing (101) a mounting fixture (8) for load testing of a cathead;
- fixing (102) the bottom of the fixture (8) onto a T-slot of test bed for load testing of the cathead;
- fixing (103) the cathead on to the fixture (8) with a sleeve assembly (1), wherein the sleeve assembly (1) is stationary while a drum assembly (2) is free to rotate;
- wrapping (104) one end of wire onto the drum shaft and other end of the drum shaft is connected to an overhead crane (10);
- connecting (105) a load cell (9) in between a wire rope (7) and overhead crane (10) for monitoring the load; and
- supplying (106) air to the diaphragm (4) and air pressure is monitored with the help of a pressure gauge (6).
2. The method (100) as claimed in claim 1, wherein the cathead is fixed on to the fixture (8) with peripheral bolts of the sleeve assembly (1).

3. The method (100) as claimed in claim 1 or 2, wherein the diaphragm (4) is inflated with an air supply, the drum assembly (2) is pushed towards sleeve assembly (1), the friction discs come in touch with each other and the drum assembly (2) is in stationary position.

4. The method (100) as claimed in claims 1-3, wherein the load is applied through the overhead crane (10), till the drum assembly (2) slips from the sleeve assembly (1) and pull load is noted.

5. The method (100) as claimed in claim 4, wherein the pull where the drum assembly (2) is slipped from sleeve assembly (1) is the rated pull of cathead at that air pressure.

6. The method as claimed in claim 5, wherein If the pull force is not meeting the rated pull load, then the catheads are dismantled and checked for assembly, friction linings (3), diaphragm (4), and springs.

7. The method are claimed in claim 6, wherein the catheads are tested at the rated load till the desired parameters are achieved.