JP2012062969A - Cooling device and method for joint part of oil-well steel pipe, and oil-well steel pipe manufacturing device - Google Patents

Abstract

[PROBLEMS] To cool a steel pipe quickly and surely to a normal temperature after heating a solid lubricant having a property of warming: fluidity and normal temperature: solid and spray-applying to a joint portion of the heated steel pipe. Offer.
Cooling for cooling the oil well steel pipe 2 after spray-applying to a heated joint portion 2a while being heated, with a solid lubricant that is fluid in a heated state and is solid at room temperature. Device 1. The cooling device 1 is disposed inside the joint portion 2a of the oil well steel pipe 2 in the steel pipe axial direction, and includes a cooling nozzle 3 for ejecting liquid nitrogen.
[Selection] Figure 1

Description

  The present invention relates to a cooling method and a cooling device for a joint portion of a steel pipe for oil well, and an apparatus for manufacturing a steel pipe for oil well. Specifically, the present invention is to heat the solid lubricant having fluidity in a heated state and solid at room temperature and spray-apply it to the joint part of the oil well steel pipe, The present invention relates to a cooling device and a cooling method for forming a solid lubricating film on a joint by quickly and reliably cooling, and an oil well steel pipe manufacturing apparatus.

  An outer surface screw for connection and a relief portion called a recess cut in a tapered shape on the inner surface are provided in a joint portion at a pipe end of the oil well steel pipe. A lubricant is applied to the joint to prevent rust and seizure. Conventionally, the coating agent which consists of compound grease has been apply | coated to the outer surface of the steel pipe for oil wells, and has been spread evenly using the brush after that.

  The OSPAR Convention on the Prevention of Marine Pollution in the Northeast Atlantic (Oslo-Paris Convention OSPAR) entered into force in 1998. As a result, regulations for preventing marine pollution have been further strengthened. For example, a country or region that has gas or oil wells with offshore rigs in its territory has the potential to discharge to the environment with respect to its drilling in order to minimize the emission of causative agents of marine pollution There is a tendency to require contractors to evaluate the environmental impact of substances and prohibit the use of substances that do not meet the standards.

  Thus, from the viewpoint of protecting the global environment, it is desirable that the lubricant used in the joint portion of the oil well steel pipe does not contain heavy metals, and particularly when drilling in the ocean, the lubricant should not flow out to the ocean. Desired.

  Patent Document 1 includes 55 to 70 parts by mass of one or two or more basic oils selected from basic sulfonates, basic salicylates, basic phenates and basic carboxylates, 20 to 25 parts by mass of fatty acid metal salts, and waxes. 10 to 20 parts by mass of the biodegradability (BOD) after 28 days in seawater is 20% or more, and does not require on-site application of grease lubricating oil. Conventional heavy metal-containing grease lubrication Strict environmental regulations because rust prevention, seizure resistance and air tightness equivalent to oil can be given to fitting parts (threaded parts and unthreaded metal contact parts) of joints of steel pipes for oil wells A composition for forming a lubricating coating that satisfies the above requirements is disclosed.

  In addition, in order to improve the on-site workability of oil well steel pipes, development and use of solid lubricants are desired in place of conventional lubricants having adhesiveness. Patent Document 2 discloses a solid lubricant that is made of a substance that has little influence on the environment and that not only prevents the outflow to the ocean but also does not have adhesiveness, and thus has good workability.

  Further, in Patent Document 3, in a pipe making process of an oil well steel pipe, a solid lubricant having a fluidity in a heated state and a property of becoming solid at room temperature is heated to, for example, about 130 ° C. and heated. The solid lubricant is sprayed onto the joint at the end of the oil well steel pipe heated to, for example, about 130 ° C., and then the joint is cooled. It is disclosed that the lubricating coating is formed thinly and uniformly with sufficient adhesion, and firmly so as not to rust during transportation and storage from the pipe mill to the oil well drilling site.

JP 2008-95019 A International Publication No. 2009/72486 Pamphlet International Publication No. 2007/42231 Pamphlet

  The oil well steel pipe in which the solid lubricating film is formed on the thread surface of the joint part by the pipe making process disclosed in Patent Document 3, is followed by a surface inspection process and a resin protector fitting process to the pipe end. Sent to. However, if the oil well steel pipe is sent to these processes while being heated to about 130 ° C., the workers in these processes may be burned, and the resin protector will fall below the wearable temperature. It is necessary to wait for wearing. For this reason, the oil well steel pipe in which the solid lubricant film is formed on the thread surface of the joint is cooled to a predetermined temperature (for example, room temperature) before being sent to the surface inspection process and the resin protector fitting process. There is a need.

  If the oil well steel pipe after the solid lubricant is spray-coated is left for a long time, the temperature of the oil well steel pipe can be lowered to, for example, room temperature. However, this significantly reduces the productivity of oil well steel pipes.

  In the present invention, liquid nitrogen is jetted toward a joint portion of an oil well steel pipe in which a solid lubricating film is formed on the thread surface of the joint portion by the process disclosed in Patent Document 3, thereby quickly and rapidly connecting the joint portion. Cooling can be ensured, and without this, productivity of oil well steel pipes can be reduced, and a solid lubricant film with lubricity can be applied to the joints with sufficient adhesion, thinly and evenly. It was completed on the basis of the important knowledge that it can be formed firmly so as not to rust during transportation and storage from the drilling site to the oil well drilling site.

  The present invention warms a solid lubricant that has fluidity in a warmed state and becomes solid at room temperature, and spray-applies to the joint of the heated steel pipe, and then the steel pipe is brought to, for example, room temperature. A cooling device for a joint portion of a steel pipe for oil well for cooling, which is disposed inside an end portion of the steel pipe toward a substantially axial direction of the steel pipe and includes a cooling nozzle for ejecting liquid nitrogen Is a cooling device for a joint portion of an oil well steel pipe.

  From another point of view, the present invention is a method in which a solid lubricant having fluidity in a heated state and solid at room temperature is heated and spray-coated on a joint portion of a heated steel pipe. A method for cooling a joint part of an oil well steel pipe for cooling the steel pipe to room temperature, for example, and injecting liquid nitrogen from a cooling nozzle arranged in an approximately axial direction of the steel pipe inside the end of the steel pipe A method for cooling a joint portion of an oil well steel pipe is characterized in that:

  In these present inventions, (a) a cooling nozzle moving mechanism for moving the cooling nozzle into and out of a predetermined position inside the steel pipe is provided, and (b) a distance between the cooling nozzle and the inner surface of the steel pipe is set to a predetermined distance. A cooling nozzle guide mechanism that is maintained at the same time, (c) an injection amount control mechanism for controlling the amount of liquid nitrogen injection from the cooling nozzle according to the temperature of the inner surface of the steel pipe, and (d) a cooling device It is desirable that the parallel part existing beyond the joint part is also cooled, and (e) the cooling nozzle is provided with a protective cover in which the liquid nitrogen injection direction is opened.

  From another viewpoint, the present invention is a cooling device for a joint part of an oil well steel pipe according to the present invention described above, and a steel pipe is laterally fed in a direction substantially perpendicular to the axial direction of the steel pipe, and the cooling device described above. And a transverse feed device for stopping at a predetermined position with respect to the oil well steel pipe manufacturing apparatus.

  According to the present invention, after heating a solid lubricant having fluidity in a heated state and solid at room temperature, and spray-applying to the joint portion of the heated steel pipe, It can be quickly and reliably cooled to room temperature. This allows a solid lubricant film having lubricity to be sufficiently applied to the thread surface of the joint portion of the steel pipe at a low cost without reducing the productivity of the oil well steel pipe. With the adhesive force, it can be formed thinly and uniformly, and more firmly so as not to rust during transportation and storage from the pipe mill to the oil well drilling site.

FIG. 1: is a perspective view which shows an example of the cooling device of the joint part of the steel pipe for oil wells which concerns on this invention in the state seen through partly while simplifying and abbreviate | omitting one part. 2 is a two-sided view showing the cooling state of the joint portion of the oil well steel pipe, in which FIG. 2 (a) is a view as seen from an arrow A in FIG. 1, and FIG. 2 (b) is a view as seen from an arrow B in FIG. FIG. FIG. 3 is an explanatory diagram showing an outline of the heat distribution of the oil well steel pipe to be cooled. FIG. 4 schematically shows an example of the arrangement relationship between oil well steel pipes and cooling nozzle nozzles (total number of holes: 76, hole diameter: 0.8 mm) during oil well steel pipe (for example, 85/8 "size) cooling. It is explanatory drawing shown. FIG. 5 is an explanatory view schematically showing an example of the arrangement of the ejection holes (total number of holes: 76, hole diameter: 0.8 mm) of the cooling nozzle. FIG. 6 is an explanatory view schematically showing the vicinity of the installation portion of the protective cover of the cooling nozzle. 7 (a) and 7 (b) are both explanatory views showing the cooling state of the joint portion of the steel pipe for oil well, and are views as seen from the arrow B in FIG.

The present invention will be described with reference to the accompanying drawings.
FIG. 1 is a perspective view showing an example of a cooling device 1 for a joint 2a of an oil well steel pipe 2 according to the present invention while partially simplifying and omitting it. FIG. 2 is a two-sided view showing the cooling state of the joint 2a of the oil well steel pipe 2, FIG. 2 (a) is a view taken along arrow A in FIG. 1, and FIG. 2 (b) is FIG. FIG.

  As shown in FIG. 1, the cooling device 1 is a device for mass-producing the oil well steel pipe 2 while cooling the steel pipe (pin) in which the solid lubricant is applied to the joint portion 2a. The cooling device 1 includes a cooling nozzle 3, a cooling nozzle moving mechanism 4, a cooling nozzle guide mechanism 5, a liquid nitrogen supply system 6, and an injection amount control mechanism (not shown). Hereinafter, these components of the cooling device 1 will be sequentially described.

[Cooling nozzle 3]
The steel pipe 2 is supported at two lower portions by two turning rollers 7 and 7. The turning roller 7 rotates in the direction of the arrow in FIG. Thereby, the steel pipe 2 rotates in the arrow direction in FIG.

  The length L in the steel pipe axial direction of the joint 2a of the steel pipe 2 is 145 mm in the example shown in FIG. In the solid lubricant spray coating process, which is a previous process (not shown), the joint portion 2a has a property of being fluid at a heated state and solid at room temperature while being heated to an appropriate temperature (for example, 130 ° C.). The solid lubricant (for example, the solid lubricant disclosed in Patent Document 3) is heated to an appropriate temperature (for example, 130 ° C.) and spray-coated.

The joint portion 2a is quickly and reliably cooled to a predetermined temperature (for example, normal temperature) by the cooling device 1 as described later.
The cooling nozzle 3 is a nozzle for injecting liquid nitrogen, and has a main body 3a made of a hollow cylinder. The cooling nozzle 3 is disposed so as to extend in a substantially axial direction of the steel pipe 2 inside the joint portion 2 a of the steel pipe 2. In the example shown in FIG. 1, the outer diameter of the main body 3a of the cooling nozzle 3 is 12.7 mm, and 69 ejection holes 3b having a diameter of 0.8 mm are formed in the main body 3a. The main body 3a is made of stainless steel. In addition, the steel pipe axial direction length of the steel pipe 2 of the cooling nozzle 3 is set longer than 213 mm and the steel pipe axial length L of the joint part 2a in order to cool the whole region of the joint part 2a.

  An injection on / off valve 9 is connected to the cooling nozzle 3 via a pipe 8a and a slide block 8b. When the injection on / off valve 9 is opened, liquid nitrogen is ejected from the ejection hole 3b of the cooling nozzle 3, and when the injection on / off valve 9 is closed, ejection of liquid nitrogen from the ejection hole 3b of the cooling nozzle 3 is stopped. .

  It should be noted that gaseous nitrogen is discharged from the injection on-off valve 9 (cooling nozzle 3) when liquid nitrogen is not injected so that each of the injection holes 3b of the cooling nozzle 3 is not frozen and clogged with moisture after the liquid nitrogen is injected. It is desirable to always eject from the side).

  Although not shown in FIG. 1, as shown in FIG. 6 to be described later, the cooling nozzle 3 is covered with a protective cover 3c made of stainless steel to increase the cooling efficiency and prevent the liquid nitrogen from being scattered. It is provided so as not to directly touch the nozzle part that is at the lowest temperature. The protective cover 3c will be described later.

  The reason why liquid nitrogen is used as the cooling medium ejected from the cooling nozzle 3 will be described. When forming a solid lubricant film on the joint 2a (thread surface) of the steel pipe 2 (pin) in the pipe making process of the oil well steel pipe, the solid lubricant is applied in a state heated to about 130 ° C. If it is allowed to stand for a long time after coating, it is cooled to about room temperature and can be transported to the next process. However, this is extremely low in productivity. Therefore, it is effective to rapidly cool the steel pipe 2 coated with the solid lubricant to improve productivity. As a method for rapidly cooling the steel pipe 2, it is easy to use air cooling or water cooling. However, any of the cooling methods has a low cooling capacity, and the productivity cannot be improved so much. Therefore, in the present invention, a low-temperature liquefied gas having a high cooling capacity is used.

  Liquid carbon dioxide and liquid nitrogen are generally known as inexpensive and relatively safe liquefied gases, but (a) avoiding atmospheric release of carbon dioxide from an environmental standpoint; Nitrogen has better cooling efficiency than liquid carbon dioxide and can reduce the amount used (when oil well steel pipes are similarly cooled, the amount of liquid carbon dioxide used is 1. (C) In order to maintain liquid carbon dioxide in a liquid state, the design pressure is generally set to 2 MPa or more, and compared to the general design pressure of liquid nitrogen equipment less than 1 MPa. Therefore, it is necessary to increase the thickness of the pressure equipment, and the liquid carbon dioxide equipment becomes more expensive than the liquid nitrogen equipment. (D) If not maintained, liquid Since it solidifies and becomes solid (generic name: dry ice) at atmospheric pressure, if carbon dioxide gas is injected with a nozzle, the liquid carbon dioxide gas in the nozzle becomes solid after clogging and clogging occurs. When heating the clogged part and sublimating the solid, the cooling equipment is heated, which causes energy loss to cool the device when operating after heating. In the case of liquid nitrogen, the nitrogen itself will not solidify, but moisture in the atmosphere may condense or freeze, so purge the vaporized nitrogen gas slightly to prevent the atmosphere from entering the nozzle, etc. Liquid nitrogen was used because of the relatively simple method.

  FIG. 3 is an explanatory diagram showing an outline of the heat amount distribution of the oil well steel pipe 2 (85/8 ″ size) to be cooled. The horizontal axis of the graph of FIG. 3 indicates the distance (mm) from the axial opening of the oil well steel pipe 2, the left vertical axis indicates the total amount of heat (J) to be cooled per 1 mm of the axial distance, and the right vertical axis. The axis indicates the heat capacity (J / K) per 1 mm of the axial distance and the temperature after heating (° C.).

The heat distribution varies depending on the type and temperature condition of the oil well steel pipe 2. In the example shown in FIG. 3, the oil well steel pipe 2 is made of SUS430, the density is 7.70 g / cm ³ , and the specific heat is 0.46 J / (g · ° C.).

  Further, the heat capacity and the total heat quantity were calculated by calculating the volume per 1 mm in the axial direction of the oil well steel pipe 2. The heat capacity per mm was calculated by approximate volume × density × specific heat. The total amount of heat to be cooled per mm was calculated by heat capacity × cooling temperature (for example, when cooling from 130 ° C. to 50 ° C., the cooling temperature is 80 ° C.).

  As shown in FIG. 3, the thickness of the oil well steel pipe 2 to be cooled changes in the axial direction, and the heat capacity of each part in the axial direction of the oil well steel pipe 2 is proportional to the thickness of the part. The heat distribution of the oil well steel pipe 2 is not constant in the axial direction of the oil well steel pipe 2. For this reason, in order to cool the steel pipe 2 uniformly, a device is needed.

  FIG. 4 shows an example of the arrangement relationship between the oil well steel pipe 2 (for example, 85/8 "size) and the ejection holes 3b (total number of holes: 76, hole diameter: 0.8 mm) of the cooling nozzle 3 during cooling. 4 and 5, the union side indicates the axial end opening side of the steel pipe 2, and the tip side in FIGS.

  Since the solid lubricating coating is applied to the joint portion (tapered portion) 2a of the oil well steel pipe 2, the cooling is mainly performed on the joint portion 2a. However, since it is heated to the right parallel part 2c from the taper part 2a by heat transfer or the like, the injection hole 3b is formed and cooled to the inside of the main body of the oil well steel pipe 2 (parallel part 2c) beyond the joint part 2a. It is desirable. For example, as shown in FIG. 4, the 45 mm portion of the first parallel portion 2c is also taken as the maximum cooling portion 2d. Further, since the parallel parts after the maximum cooling part 2d are also slightly heated by heat transfer, the maximum cooling part 2d and the subsequent parts are used for the purpose of reducing the overall temperature as uniformly as possible and minimizing the loss of liquid nitrogen. It is desirable to form the ejection holes 3b with a number significantly reduced from the maximum cooling part 2d, for example, a number of 1/2 or less. In FIG. 4, eight ejection holes 3b are disposed in a range 2e of 45 mm after the maximum cooling portion 2d, and four ejection holes 3b are disposed in a range 2f of 45 mm.

FIG. 5 is an explanatory diagram schematically showing an example of the arrangement of the ejection holes 3 a (total number of holes: 76, hole diameter: 0.8 mm) of the cooling nozzle 3.
The 64 ejection holes 3b of the maximum cooling section 2d are arranged in 21 rows, 22 rows, and 21 rows in the A row, B row, and C row, respectively, with an angle of 45 degrees from the central B row.

In the range 2e, four ejection holes 3b are arranged in each of the A row and the C row, and the angle is 90 degrees. In the range 2f, the ejection hole 3b is arranged only at the center B.
The reason why the angle of the array of the ejection holes 3b is set to 45 degrees from the center B row is that the injected liquid nitrogen hits the oil well steel pipe 2 and rebounds is collected in the protective cover 3c described later to improve the cooling efficiency. is there. What is necessary is just to adjust suitably the arrangement | sequence and angle of the ejection hole 3b in the range which can achieve such an objective.

FIG. 6 is an explanatory view schematically showing the vicinity of the installation portion of the protective cover 3 c of the cooling nozzle 3.
The cooling nozzle 3 is provided with a protective cover 3c in which the liquid nitrogen injection direction is opened. It is desirable that the opening width of the protective cover 3c is such that the injected liquid nitrogen collides with the oil well steel pipe 2 and bounces back, and then is collected again in the protective cover 3c. By attaching the protective cover 3c, the cooling efficiency is improved. According to the test results, there is a difference of 1: 1.9 in the time for cooling to the same temperature, with and without a protective cover, and the amount of liquid nitrogen used is also proportional to this time difference. The reason for this is that the sprayed liquid nitrogen bounces after colliding with the oil well steel pipe 2 is collected in the protective cover 3c without being scattered and drops down the oil well steel pipe 2 again through the protective cover 3c. It is thought that it contributes to the cooling of the steel pipe 2 and the cold air accumulated in the protective cover 3c contributes to the cooling of the oil well steel pipe 2.

  Therefore, it is desirable to arrange the protective cover 3c as small as possible and as close to the oil well steel pipe 2 as possible. The protective cover 3c is large enough to accommodate rollers 20 and 21, which will be described later, and has a width of 50 mm, a depth of 40 mm, and a clearance of 5 mm from the oil well steel pipe 2 during operation.

The purpose of installing the protective cover 3c is to improve the cooling efficiency and prevent the liquid nitrogen from scattering, and also to prevent the operator from accidentally directly touching the nozzle portion that is at a very low temperature.
It is desirable that the specific number and the diameter of the ejection holes 3b for injecting liquid nitrogen are appropriately set according to the difference in the total heat quantity that varies depending on the diameter and thickness of the oil well steel pipe 2.

Furthermore, it is desirable that the distance between the ejection hole 3b and the oil well steel pipe 2 is as short as possible. As a result of the test, the cooling capacity decreased by 24% when the distance of 30 mm was increased.
In the cooling device 1, since rollers 20 and 21 to be described later are cooled while contacting the oil well steel pipe 2, the distance between the ejection hole 3b and the oil well steel pipe 2 is set to be constant at about 14 mm. It is.

  As described above, the cooling device 1 is disposed inside the joint portion 2a that is an end portion of the oil well steel pipe 2 so as to face the substantially axial direction of the oil well steel pipe 2, and the cooling nozzle 3 for ejecting liquid nitrogen. Is provided.

[Cooling nozzle moving mechanism 4]
The pipe 8a and the slide block 8b connected to the cooling nozzle 3 are a cooling nozzle pipe radius horizontal movement ball screw 10 and a cooling nozzle pipe radius horizontal movement ball screw 10 for driving the cooling nozzle pipe radius horizontal movement ball screw 10. Connected to the servo motor 11. The cooling pipe 8a and the slide block 8b move in the radial horizontal direction of the steel pipe 2 by starting the servo motor 11 for moving the cooling nozzle pipe radius in the horizontal direction, whereby the cooling nozzle 3 also moves in the radial horizontal direction of the steel pipe 2. Moving.

  The cooling nozzle 3, the pipe 8, the injection on / off valve 9, the cooling nozzle pipe radius horizontal movement ball screw 10, and the cooling nozzle pipe radius horizontal movement servo motor 11 are all mounted on the support plate 12. Is done. The support plate 12 has a rectangular flat plate shape and extends in the axial direction of the steel pipe 2.

  The support plate 12 is connected to a cooling nozzle pipe radial vertical movement ball screw 13 and a cooling nozzle pipe radial vertical movement servo motor 14 that drives the cooling nozzle pipe radial vertical movement ball screw 13. The support plate 12 is moved in the direction perpendicular to the radius of the steel pipe 2 by starting the servo motor 14 for moving the cooling nozzle pipe in the radial direction of the radius, whereby the cooling nozzle 3 is also moved in the direction perpendicular to the radius of the steel pipe 2.

  Further, the slide block 8b is connected to an air cylinder 15 for moving the cooling nozzle pipe in the axial direction. The cooling nozzle pipe axial movement air cylinder 15 is mounted on the support plate 12. The slide block 8 b moves in the axial direction of the steel pipe 2 by activating the cooling nozzle pipe axial movement air cylinder 15, whereby the cooling nozzle 3 also moves in the axial direction of the steel pipe 2.

  The cooling nozzle pipe radius vertical movement ball screw 13 and the cooling nozzle pipe radius vertical movement servo motor 14 are both supported by the cooling nozzle movement mechanism main body 16.

  The cooling nozzle moving mechanism main body 16 is mounted on the bottom thereof with a main body axial movement ball screw 17 and a main body axial movement servo motor 18 that drives the main body axial movement ball screw 17. The main body axial movement ball screw 17 is mounted on the base substrate 19. The cooling nozzle moving mechanism main body 16 moves in the axial direction of the steel pipe 2 by activating the servo motor 18 for movement in the main body axial direction, whereby the cooling nozzle 3 also moves in the axial direction of the steel pipe 2.

Thus, the cooling mechanism 3 is supported by the cooling nozzle moving mechanism 4 so as to be displaceable in three directions, ie, the vertical direction, the left-right direction, and the steel pipe axial direction so as to be positioned at the center of the steel pipe 2.
First, the cooling nozzle 3 is preliminarily adjusted to a position coincident with the center of the steel pipe 2 by the cooling nozzle pipe radius moving servo motor 11 and the cooling nozzle pipe radius moving servo motor 14.

  And after the steel pipe 2 is conveyed by the transverse feed apparatus mentioned later and arrange | positioned on the turning rollers 7 and 7, the support plate 12 carrying the cooling nozzle 3 is activated by the servo motor 18 for main body axial movement. The steel pipe 2 moves forward until the pipe end position is detected, and stops at that position. Thereafter, the cooling nozzle 3 further moves forward when the cooling nozzle pipe axial movement air cylinder 15 is activated, and the cooling nozzle 3 is inserted to a predetermined position inside the joint portion 2a of the steel pipe 2 and stopped.

  After the cooling nozzle 3 is inserted to a predetermined position inside the joint portion 2a of the steel pipe 2, the cooling nozzle pipe radius moving servo motor 11 is activated toward the inner surface of the steel pipe 2, and the cooling nozzle 3 is moved to the steel pipe 2. Press against the inside. When the proximity switch arranged in the vicinity of the cooling nozzle 3 is turned on, the cooling nozzle 3 is moved in the radial direction until the cooling nozzle 3 comes into contact with the inner surface of the joint portion 2 a of the steel pipe 2.

  Unlike the cooling nozzle moving mechanism 4 described above, the cooling nozzle moving mechanism may be configured by, for example, a general-purpose articulated industrial robot. In this case, the articulated industrial robot may be held by the cooling nozzle 3 via an appropriate end effector (effector).

  Thus, the cooling device 1 includes the cooling nozzle moving mechanism 4 for taking the cooling nozzle 3 into and out of a predetermined position inside the joint portion 2a of the steel pipe 2.

[Cooling nozzle guide mechanism 5]
At both ends of the cooling nozzle 3, rollers 20 and 21 are arranged as the cooling nozzle guide mechanism 5. As described above, the rollers 20 and 21 are arranged so that the cooling nozzle 3 is moved in the horizontal direction toward the inner surface of the steel pipe 2 after the cooling nozzle 3 is inserted to a predetermined position inside the joint portion 2a of the steel pipe 2. And the cooling nozzle 3 is pressed against the inner surface of the steel pipe 2 to come into contact with the inner surface of the joint portion 2a of the steel pipe 2, whereby each of the ejection holes 3b formed in the cooling nozzle 3 and the joint of the steel pipe 2 are contacted. The distance between the inner surface of the part 2a is kept constant.

  Thus, the cooling device 1 includes the cooling nozzle guide mechanism 5 that keeps the distance between the cooling nozzle 3 and the inner surface of the steel pipe 2 at a predetermined distance.

[Liquid nitrogen supply system 6]
The liquid nitrogen supply system 6 is for supplying liquid nitrogen to the cooling nozzle 3. The liquid nitrogen 22 is stored in a tank 23 installed outdoors, and is transported and replenished by a tank car (not shown).

  As shown in FIG. 1, the liquid nitrogen supply system 6 includes a tank 23, a pipe 24, a main opening / closing valve 25, a liquid nitrogen storage header level adjusting valve 26, a liquid nitrogen storage header 27, and a liquid nitrogen storage level. It has a sensor 28, a safety valve 29, and an injection on / off valve 9.

  Before using the cooling device 1, the liquid nitrogen 22 is supplied in advance until it accumulates to a level in the liquid nitrogen storage header 27. The supply amount of the liquid nitrogen 22 from the tank 23 to the liquid nitrogen storage header 27 is controlled by controlling the on / off control of the liquid nitrogen storage header level adjusting valve 26 installed in front of the liquid nitrogen storage header 27. The amount of liquid nitrogen 22 accommodated in the liquid nitrogen storage header 27 is set within a certain range.

  The safety valve 29 disposed on the upper part of the liquid nitrogen storage header 27 is activated to eject nitrogen when the pressure in the liquid nitrogen storage header 27 becomes a predetermined level or more due to evaporation of the liquid nitrogen 22.

  The liquid nitrogen storage header 27 is disposed at a level higher than that of the cooling nozzle 3, and is configured to supply liquid nitrogen to the cooling nozzle 3 from the bottom of the liquid nitrogen storage header 27. The injection on / off valve 9 for sending liquid nitrogen to the cooling nozzle 3 is preferably installed in the immediate vicinity of the cooling nozzle 3 to enhance the responsiveness.

  The upper portion of the liquid nitrogen storage header 27 is always filled with gaseous nitrogen under pressure, and as described above, when the liquid nitrogen is not ejected from the cooling nozzle 3, the gaseous nitrogen is turned on. It is desirable that the nozzle is constantly ejected from the outlet side (cooling nozzle 3 side) of the off valve 9 to prevent clogging due to freezing of the cooling nozzle 3.

  As described above, the liquid nitrogen supply system 6 is connected to the tank 23 in order to supply a stable and sufficient amount of liquid nitrogen used for cooling the joint portion 2a of the steel pipe 2, and the pipe 24 is connected to the cooling nozzle 3. Is installed at a higher position, a safety valve 29 is installed at the top of the pipe 24, and a liquid nitrogen storage header 27 is arranged in the immediate vicinity of the cooling nozzle 3 and below the pipe 24 from the tank 23 for stable supply, In order to keep the level of the liquid nitrogen storage header 27 constant, the liquid nitrogen storage header level adjusting valve 26 disposed at the connection portion with the pipe 24 connected to the tank 23 is controlled to open and close.

In more supplementary, in order to cool the steel pipe 2 efficiently, it is necessary to stably supply the liquid body of free nitrogen vaporized gas. The cooling device 1 arranges the liquid nitrogen storage header (gas-liquid separator) 27 as close to the cooling nozzle 3 as possible to shorten the distance from the liquid nitrogen storage header 27 to the cooling nozzle 3, and the vaporized gas generated therebetween Can be reduced. Further, the vaporized gas generated between the liquid nitrogen supply tank 23 installed outdoors and the liquid nitrogen storage header 27 can be removed in the immediate vicinity of the cooling nozzle 3. The liquid nitrogen storage header 27 is controlled by a liquid nitrogen storage level sensor 28 so that the liquid level is always higher than a certain level. When the liquid amount decreases, the gas in the liquid nitrogen storage header 27 is automatically released to the atmosphere. To keep the liquid level high. However, since it is normally consumed effectively as a purge gas for preventing condensation and icing of the cooling nozzle 3, there is little wasted air emission during normal continuous operation.

  Thus, the cooling device 1 includes the liquid nitrogen supply system 6 for supplying liquid nitrogen to the cooling nozzle 3.

[Injection amount control mechanism]
The cooling device 1 includes a temperature measuring device (for example, a non-contact thermometer) that measures the temperature of the inner surface of the joint portion 2a of the oil well steel pipe 2, and liquid nitrogen from the cooling nozzle 3 according to the temperature measurement result of the temperature measuring device. It is desirable to provide an injection amount control mechanism (not shown) for controlling the injection amount.

  Thereby, after injecting liquid nitrogen from the cooling nozzle 3 toward the joint part 2a while rotating the oil well steel pipe 2, it was confirmed that the surface of the joint part 2a was lowered to a predetermined temperature by a non-contact thermometer, Thereby, the injection amount control mechanism outputs a control signal to the liquid nitrogen supply system 6, thereby stopping the injection of liquid nitrogen from the cooling nozzle 3.

  Thereafter, the cooling nozzle moving mechanism 4 performs an operation opposite to the above-described operation, and the cooling nozzle 3 is retracted / returned to the above-described original position, whereby the cooling by the cooling device 1 is completed. Thereafter, the oil well steel pipe 2 that has been cooled by the cooling device 1 is unloaded, and the cooling of the next oil well steel pipe is awaited.

The cooling device 1 is configured as described above.
In addition, the manufacturing apparatus for the oil well steel pipe 2 according to the present invention laterally feeds the cooling device 1 and the steel pipe 2 in a direction substantially perpendicular to the axial direction of the steel pipe 2 (indicated by the white arrow in FIG. 1). A transverse feed device (not shown) for stopping at a predetermined position (the position illustrated in FIG. 1) with respect to the cooling device 1 is provided. Since this lateral feed device is well known to those skilled in the art as this type of transport device, a description of the lateral feed device will be omitted.

According to this manufacturing apparatus, the oil well steel pipe 2 is cooled by a procedure listed below in a line in which the oil well steel pipe is continuously traversed for mass production.
(I) When the oil well steel pipe 2 is carried into the front surface of the cooling device 1, the cooling nozzle 3 automatically advances and stops after detecting the pipe end position of the oil well steel pipe 2.

(Ii) The cooling nozzle 3 is advanced so that the cooling nozzle 3 is effectively inside the oil well steel pipe 2 and in the center of the oil well steel pipe 2, and the cooling nozzle 3 stops at a predetermined position.
(Iii) The cooling nozzle 3 is moved in the radial horizontal direction or the radial vertical direction, pressed against the inner surface of the oil well steel pipe 2, and the distance between the cooling nozzle 3 and the joint portion 2a of the oil well steel pipe 2 is kept constant.

  7 (a) and 7 (b) are both explanatory views showing the cooling state of the joint portion 2a of the oil well steel pipe 2, and are views as seen from arrow B in FIG. FIG. 7A shows a case where the cooling nozzle 3 is moved in the radial horizontal direction, and FIG. 7B shows a case where the cooling nozzle 3 is moved in the radial vertical direction.

  The oil well steel pipe 2 having a temperature of 130 ° C. before being cooled by the cooling device 1 was cooled by the cooling means shown in FIG. 7 (a) or FIG. 7 (b). The liquid nitrogen injection time t from the cooling nozzle 3 was 60, 80 or 100 seconds. The results are summarized in Table 1. In Table 1, the tube inner surface was cooled, the temperature measurement point was basically the tube outer surface, and the measured value of the tube inner surface for 100 seconds was measured after the cooling nozzle 3 was taken out.

  From the results shown in Table 1, it can be seen that the cooling effect is greater when liquid nitrogen is injected in the horizontal direction than in the vertical direction as shown in FIG. This is because the liquefied nitrogen injected from the nozzle collides with the oil well steel pipe, and then the liquefied nitrogen remaining in the liquid state flows and moves to the bottom surface of the oil well steel pipe due to gravity, compared with the case where the liquefied nitrogen is injected toward the bottom face. This is considered to cool a large area.

(Iv) By injecting liquid nitrogen 22 from the cooling nozzle 3, the joint portion 2a of the steel pipe 2 (the entire periphery of the heated screw) is cooled.
(V) The supply of liquid nitrogen is automatically stopped after the joint portion 2a of the steel pipe 2 has fallen to a predetermined temperature, the cooling device 1 is returned to its original position, and the next steel pipe for oil well is prepared for cooling.

  Thus, according to the present invention, the liquid nitrogen is ejected from the cooling nozzle 3 disposed in the axial direction of the steel pipe inside the joint portion 2 of the oil well steel pipe 2, thereby connecting the joint of the oil well steel pipe 2. A solid lubricant film having lubricity is applied to the thread surface of the inner surface of the part 2 with good adhesion, thinness and uniformity, and furthermore, rust is not generated during transportation and storage from the pipe mill to the oil well drilling site. For example, after heating the solid lubricant disclosed in Patent Document 3 and spray-applying to the joint portion of the heated oil well steel pipe 2, This oil well steel pipe 2 can be quickly and reliably cooled to, for example, room temperature.

  Specifically, the cooling device 1 can cool an oil well steel pipe having a diameter of 340 mm from 130 ° C. to near room temperature in a cooling time of about 100 seconds, and the amount of nitrogen used at that time is one. It was 17 kg per book.

DESCRIPTION OF SYMBOLS 1 Cooling device 2 Oil well steel pipe 2a Joint part 2c Parallel part 2d Maximum cooling part 2e 45mm range 2f 45mm range 3 Cooling nozzle 3a Body 3b Ejection hole 3c Protective cover 4 Cooling nozzle moving mechanism 5 Cooling nozzle guide mechanism 6 Liquid nitrogen supply System 7 Turning roller 8a Pipe 8b Slide block 9 Injection on-off valve 10 Cooling nozzle pipe radius horizontal movement ball screw 11 Cooling nozzle pipe radius horizontal movement servo motor 12 Support plate 13 Cooling nozzle pipe radius vertical movement ball Screw 14 Cooling nozzle pipe radius vertical movement servo motor 15 Cooling nozzle pipe axial movement air cylinder 16 Cooling nozzle moving mechanism main body 17 Main body axial movement ball screw 18 Main body axial movement servo motor 19 Base base 20, 2 1 Roller 22 Liquid Nitrogen 23 Tank 24 Pipe 25 Main Open / Close Valve 26 Liquid Nitrogen Storage Header Level Adjustment Valve 27 Liquid Nitrogen Storage Header 28 Liquid Nitrogen Storage Level Sensor 29 Safety Valve

Claims (8)

Cooling of joints of oil well steel pipes to cool the steel pipe joints after spray application to the heated steel pipe joint parts with fluidity in a heated state and solids that are solid at room temperature. A device,
A cooling device for a joint portion of a steel pipe for oil wells, which is disposed inside an end portion of the steel pipe toward a substantially axial direction of the steel pipe and includes a cooling nozzle for ejecting liquid nitrogen.   The apparatus for cooling a joint portion of an oil well steel pipe according to claim 1, further comprising a cooling nozzle moving mechanism for taking the cooling nozzle into and out of a predetermined position inside the steel pipe.   The cooling device for a joint part of an oil well steel pipe according to claim 1 or 2, further comprising a cooling nozzle guide mechanism that maintains a distance between the cooling nozzle and an inner surface of the steel pipe at a predetermined distance.   The oil well described in any one of Claims 1-3 provided with the injection amount control mechanism for controlling the injection amount of the said liquid nitrogen from the said cooling nozzle according to the temperature of the inner surface of the said steel pipe. Cooling device for steel pipe joints.   The said cooling device cools also the parallel part which exists beyond the said joint part, The cooling device of the joint part of the steel pipe for oil wells described in any one of Claim 1- Claim 4 characterized by the above-mentioned.   The said cooling nozzle is provided with the protective cover by which the injection direction of the said liquid nitrogen was open | released, The cooling device of the joint part of the steel pipe for oil wells described in any one of Claim 1-5 . A method for cooling a joint part of an oil well steel pipe for cooling the steel pipe after spraying and applying to a steel pipe joint part with a solid lubricant which is fluid in a heated state and solid at room temperature. ,
A method for cooling a joint portion of a steel pipe for oil wells, characterized in that liquid nitrogen is ejected from a cooling nozzle arranged inside the end portion of the steel pipe toward a substantially axial direction of the steel pipe. A cooling device for a steel pipe joint part for oil wells according to any one of claims 1 to 6,
An apparatus for producing an oil well steel pipe, comprising: a transverse feed device for transversely feeding the steel pipe in a direction substantially perpendicular to the axial direction of the steel pipe and stopping at a predetermined position with respect to the cooling device.

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