JPH0130037B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing an insulating connection device for piping, which connects and fixes adjacent ends of metal pipes through which high-pressure or high-temperature liquids flow, for example. Specifically, insulated connections for piping that electrically insulate the ends and prevent current from flowing from one side of the metal pipe to the other, are easy to connect, and maintain a high degree of airtightness, including the connection area. The present invention relates to a method for manufacturing a device.

[Prior art]

Metal pipe connection devices are widely used for gas, water, oil, etc. distribution pipes installed above or underground, as well as for well pipes that suck up oil, hot water, etc. from deep underground. External power supply systems have come into widespread use to prevent corrosion of metal pipes. In this case, a DC voltage is applied to the metal tube. This applied voltage varies depending on the surrounding environmental conditions, but in order to appropriately realize this condition and to prevent accidents caused by current leaking to the outside, there is a sudden demand for insulated connection devices with electrical insulation properties. It increased.

The main characteristics required of this insulated connection device are as follows. First, room temperature to 250~300℃
It is required not only to maintain the necessary electrical insulation properties in the temperature range of °C or under conditions of repeated temperature rises and falls, but also to maintain high thermal and mechanical impact strength and a high degree of air (water) density. Ru.
Furthermore, regarding mechanical strength, especially when used for well pipes, it is essential to suspend long metal pipes, so it is important to maintain sufficient tensile strength to withstand this suspension, and to prevent aging. In addition to general characteristics such as long-term reliability, it is also required that the connection process with metal pipes be easy to perform without requiring special equipment. For example, in the case of steel pipes for oil wells, the dimensions of the pipe body, connecting devices, connection screws, etc. are standardized by American Petroleum Institute standards (hereinafter referred to as API standards). Therefore, it is ideal for insulated connection devices to comply with the specifications for metal connection devices.

While maintaining the necessary characteristics mentioned above,
An embodiment of an insulated connection device whose dimensions and other specifications conform to metal connection devices will be described with reference to FIG.
The first tubular member 4 has an inner peripheral tube 4 on the inner peripheral side of the main body 42.
1, and a male screw 45 having a root diameter larger than the outer diameter of the inner circumferential tube 41 is screwed onto the tip. Second
The tubular member 5 has an outer circumferential tube 51 on the outer circumferential side of a main body 52, and a male screw 55 having a diameter smaller than the inner diameter of the outer circumferential tube 51 at the tip and screwed into the male screw 45 of the first tubular member 4 is screwed. It is set up. The male thread 45 of the first tubular member 4 is threaded through the male thread 55 of the second tubular member 5, and a gap 6 is provided between the first tubular member 4 and the second tubular member 5. The gap 6 is filled with an insulator 7 made of glass or mica plastic material to insulate both the tubular members 4 and 5 and seal them tightly.
Connecting screws 3 compliant with API standards are screwed onto the inner peripheral surfaces of the main bodies 42 and 52, and are screwed together with male connecting screws screwed onto the outer peripheral end of the tube body 2 (not shown). , the connection is made while maintaining the insulation of the tube body 2.

The characteristics of this insulated connection device are that the shape and dimensions conform to the API standard connection device, and the connection screw 3
is screwed onto the inner periphery of the main body 42, 52 having a wall thickness of a predetermined dimension. In the connection process with the pipe body 2, the threaded base body 8 is tightened with a large torque to maintain air (water) tightness.
2.52, it is thick, and since it is located at a part unrelated to the insulating component, it can be connected without affecting the insulating component and without requiring special equipment or jigs.

The glass and mica plastic bodies that make up the insulator are made from a mixed powder of vitreous powder and mica powder, and the raw material powder is heated to a temperature at which the vitreous material softens and flows under pressure. A composite insulator obtained by heating and press-molding in a heated state.

The insulating connection device is manufactured by first molding an insulating connection device base and then machining it. A conventional method of molding an insulated connection device base will be explained with reference to FIG. FIG. 5a shows the state immediately before pressure forming, and FIG. 5b shows the state after pressure forming is completed. Note that parts having the same functions as those in FIG. 4 are given the same symbols. The outer circumferential diameters of the first tubular member 4 and the second tubular member 5 are equal to or larger than those in FIG. 4, and the inner circumferential diameters are smaller. The support portion 46 is provided at the tip of the inner circumferential tube 41 and placed on the main body 52 to maintain the gap 6. 9 is a wall of the split structure, 10 is a frame, and 11 is a support stand of the split structure.
located in a fitted state between the tubular member 5 and the wall portion 9;
The upper surface is equal to the upper surface of the second tubular member 5. The pressurizing metal 12 is formed to fit into the wall portion 9 and the first tubular member 4 . The presser metal 13 is located on the upper part of the first tubular member 4, and is connected to a driving part (not shown).
The first tubular member 4 is pressurized by the pressurizing force. Molding mold 9, 10, 1 composed of the above four parts
1, 12 and pusher 13 are used. The preform 14 is made by adding water to a mixed powder of vitreous powder and mica powder, which are the raw materials for the insulator 7, to make it moist, and then forming a through hole in the center using another mold (not shown). It is formed into a cylindrical product and dried to remove moisture.

The molding is performed by forming the wall portion 9, the frame 10, and
Pressure metal 1 with support stand 11 assembled and unassembled
2 and heated to the treatment temperature. Note that the presser metal 13 is not heated. Further, the first tubular member 4 is assembled by threading its male screw 45 through the male screw 55 of the second tubular member 5 and placing the support portion 46 on the main body 52, and is then processed together with the preform 14. Heat to constant temperature. When heating is completed, the assembled first and second tubular members 4 and 5 are inserted into the wall 9, and then the pusher 1 is inserted.
3 is placed on the first tubular member 4, and then the preform 14 is inserted onto the support base 11. Finally, the pressurized metal 12 is placed on the preform 14. This situation is shown in Figure 5a. For molding, first the presser metal 13 is pressurized by a drive unit (not shown) of a pressure molding machine, and then the presser metal 12 is pressurized by another drive unit. The preform 14 flows and fills the gap 6 formed by the first tubular member 4 and the second tubular member 5 to form an insulator 7 made of glass or mica plastic. The state at this time is shown in FIG. 5b. When the pressure molding process is completed, the molded product is cooled to a predetermined temperature, the mold for molding is disassembled, and the molded product insulating connection device base 15 is taken out. The thus formed insulating connection device base 15 is machined into the insulating connection device shown in FIG. 4, and the manufacturing is completed.

In the above molding process, the presser metal 13 is pressurized before the pressurizer 12 pressurizes the preform 14 . This is because the preform 14 is pressurized and the first,
When the gap 6 formed by the second tubular members 4 and 5 is filled, floating pressure is generated on the lower surface 47 of the main body and the lower surface 48 of the inner tube of the first tubular member 4, causing the first tubular member 4 to float. This is to prevent this phenomenon from occurring. Naturally, the total pressing force applied to the pusher 13 needs to be greater than the total floating pressure.

Generally, in order to mold glass or mica plastic bodies, the pressure applied to the preform 14 must be 1 to 1.5 ton/cm ² . Since this pressure of 1 to 1.5 ton/cm ² is applied to the entire lower surface of the first tubular member 4, that is, the lower surface 47 of the main body and the lower surface 48 of the inner tube, the floating pressure becomes extremely large. For example, according to the API standard, if the diameter of the delivery pipe is 10 3/4 inches, the inner diameter of the connecting device is 256.4 mmφ, the outer diameter is 298.4 mmφ, and the area receiving floating pressure is 183 cm ² , and the pressing force of the preform 14 is
If set to 1.2ton/ ^cm2 , the total floating pressure will be 220ton. The inner diameter of the preformed body 14 is 298 mmφ, and the outer diameter is 338 mm.
If mmφ, the total pressure applied to the preform is 240 tons.
becomes. That is, the insulated connection device base 1 is
5, the main drive shaft for pressurizing the preform 14 is equipped with a weight of 240 tons, and a sub-drive section of 220 tons for pressurizing the presser metal 13 independently from the main drive section is installed inside this main drive section. A pressure molding machine is required. When an independent sub-drive section is provided inside the main drive section as described above, the capacity of the sub-drive section is generally limited to about 30% of the capacity of the main drive section. Therefore, if the capacity of the sub-drive section is set to 220 tons, the capacity of the main drive section will inevitably be approximately 730 tons. The maximum diameter of the delivery pipe is 20 inches, and various sizes are available, with pipes thicker than the 10 3/4 inch example above being widely used.

As is clear from the above explanation, in the conventional molding method, the pressure molding machine used as the molding equipment becomes huge, which inevitably causes the product price to rise, and because the equipment becomes large, the molding operation becomes difficult. Many problems arose on the manufacturing side, such as the difficulty of stable molding, and as a practical matter, there was a fatal flaw in that it became impossible to produce large-sized products.

[Summary of the invention]

The present invention has been made in order to solve the above-mentioned drawbacks, and it is possible to use an insulating connection device whose outer diameter conforms to API standards and maintains extremely excellent characteristics by using a special and large-capacity pressurizing device as in the past. In order to obtain a method for manufacturing large-sized products at low cost without using a molding machine, a cylinder B having an inner diameter equal to that of the cylinder A and a smaller outer diameter is placed at one end of the cylinder A, and a cylinder B having an outer diameter smaller than that of the cylinder A is placed at one end of the cylinder A. A cylindrical body C with an inner diameter equal to that of the cylindrical body A and a smaller outer diameter is attached to the end thereof, a male screw whose root diameter is larger than the outer diameter of the cylindrical body C is attached to the end of the cylindrical body C, and a cylindrical body C is attached to the tip of the male screw. A first cylinder having a cylindrical body D having an equal inner diameter and a small outer diameter, and further having one or more through holes parallel to the outer circumferential surface near the outer periphery of the cylindrical body A.
a step of forming a tubular member, and a step of forming a tubular member F having an outer diameter equal to that of the tubular member E and a larger inner diameter at one end of the tubular member E, and a tubular member F having a diameter smaller than the inner diameter of the tubular member F at the tip of the tubular member F; forming a second tubular member having a male thread that is screwed into the male thread of the tubular member; and threading the first tubular member into the second tubular member and holding the center to create a gap. a step of assembling an insulating material made of glass powder and mica powder into a cylindrical preform, and a step of assembling the first and second tubular members, the preform, a step of heating the molding mold to each predetermined temperature; a step of arranging an external molding mold around the outer periphery of the first tubular member and the second tubular member assembled in the heated state; A process of inserting the preform into the space formed by the cylinder B and the molding die, and pressurizing the preform to fill the gap formed by the first tubular member and the second tubular member. a step of configuring the insulator, a step of removing the cylinder B by machining, processing the inner peripheral surface, removing the cylinder D and exposing the insulator, and screwing a connecting screw on the inner peripheral surface. The present invention provides a method for manufacturing an insulating connection device for piping, which comprises the steps of:

[Embodiments of the invention]

The second tubular member 5 used in the manufacturing method of the insulating connection device is the one used in the conventional manufacturing method, and the first tubular member is the structural product shown in FIG. 1. Note that parts having the same functions as those in FIG. 5 are denoted by the same symbols, and explanations thereof will be omitted. In the figure, reference numeral 49 denotes an auxiliary wall for inserting the preform 14 during molding, and is provided at the upper part of the main body 42. Reference numeral 16 denotes through holes that penetrate from the upper surface of the main body 42 to the lower surface 47 of the main body, and three of them are provided at positions close to the outer peripheral surface. This number is not limited to three and may be increased or decreased as necessary.

The molding method will be explained with reference to FIG. The molding die includes a divided wall part 9 whose height is equal to the height of the auxiliary wall 49 in the assembled state and whose inner periphery fits into the outer periphery of each tubular member 4, 5, a frame 10, and a pressurizing metal. 12 of 3
Use something made up of parts. The molding is carried out in the same way as the conventional method described with reference to FIG. 5, in which the molding molds 9, 10, 12, the assembled tubular members 4, 5, and the preform 14 are heated to a predetermined temperature, and As shown in FIG. 2a, first the assembled tubular members 4 and 5 are inserted into the wall 9, and then the preform 14 is inserted into the space defined by the auxiliary wall 49 of the first tubular member. do. Finally, the pressurized metal 12 is placed on the preform 14. This situation is shown in Figure 2a. Next, the preform 14 is pressurized via the press metal 12 by a pressure molding machine. The pressurized preform 14 flows through the through hole 16, reaches the gap 6 formed by the first tubular member 4 and the second tubular member 5, and fills all the gaps to form the insulator 7. The state at this time is shown in FIG. When the above pressure molding process is completed, the molded product is cooled to a predetermined temperature, the mold is disassembled, and the molded product is taken out. The thus formed insulating connection device base 15 is machined to complete the final manufacturing into the insulating connection device shown in FIG. 3.

〔Effect of the invention〕

As is clear from the above description, according to the manufacturing method according to the present invention, the phenomenon that the first tubular member 4 floats when the preform 14 is pressurized does not occur at all. Therefore, unlike conventional manufacturing methods, there is no need to apply pressure to prevent the first tubular member 4 from floating prior to pressurizing the preform 14, so a pressure molding machine with a special mechanism is not required. This eliminates the need to use a conventional pressure molding machine, making it possible to use a general pressure molding machine. Further, unlike the conventional manufacturing method, the support stand 11 is not required and the inner wall of the wall portion 9 fits into both the tubular members 4 and 5, so that the mold itself can be miniaturized. This will directly lead to a decline in production prices. Furthermore, since the inner and outer diameter dimensions of the preform 14 are reduced, the total pressure inevitably decreases even if the pressing force is maintained at the same level. Incidentally, if the pressing force is equal to 1.2 ton/cm ² , in the case of the conventional manufacturing method, if the delivery pipe diameter is 10 3/4 inches,
As shown in the previous embodiment, a total pressure of 240 tons was required to pressurize the preform 14, but in the case of the method according to the present invention, a total pressure of 220 tons is sufficient. This corresponds to the floating pressure. Also delivery tube 20
The outer diameter of the connecting device for inches is 533.4 mm, but when manufacturing an equivalent insulated connecting device, the total pressure applied to the preform 14 during molding of the insulating connecting device base is about 470 tons. According to the manufacturing method according to the present invention, as is clear from the above description, special pressure molding is used to form the insulating connection base, which includes a sub-drive section that is driven independently in the same direction in the center of the main drive section. Does not require a machine. Moreover, the total pressure applied to the preform is reduced, making it possible to easily manufacture large-sized, for example, 20-inch insulated connection devices, which would have been nearly impossible to manufacture using conventional manufacturing methods. Due to miniaturization, the soaring prices associated with equipment were inevitably eliminated, and production became possible at low cost without being restricted by the size of the shape.

As described above, the manufacturing method according to the present invention completely eliminates all the conventional unavoidable fatal defects, and has extremely high technical and practical value.

[Brief explanation of drawings]

Figures 1a and b and Figures 3a and b are a plan view and a vertical sectional view of the embodiment of the present invention, and Figures 2a and b depict the state of the embodiment of the present invention immediately before and after completion of pressure forming, respectively. 4 is a longitudinal sectional view showing an example of an insulated connection device conforming to API standards, and FIGS. 5a and 5b show respective states of a conventional insulated connection base immediately before and after completion of pressure molding. FIG. 3... Connection screw, 4... First tubular member, 5
... second tubular member, 6 ... void, 7 ... insulator, 8 ... threaded base, 9 ... wall, 10 ... frame,
DESCRIPTION OF SYMBOLS 11... Support stand, 12... Pressure metal, 13... Push metal, 14... Preformed body, 15... Insulated connection device base, 16... Through hole. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1 At one end of the cylinder A, a cylinder B with an inner diameter equal to that of the cylinder A and a smaller outer diameter, and at the other end of the cylinder A a cylinder C with an inner diameter equal to that of the cylinder A and a smaller outer diameter. A male screw having a root diameter larger than the outer diameter of the cylinder C is provided at the end, and a cylinder D having an inner diameter equal to that of the cylinder C and a smaller outer diameter is provided at the tip of the male screw, and further near the outer circumference of the cylinder A. A step of forming a first tubular member holding one or more through holes parallel to the outer circumferential surface, and forming a cylindrical member F having an outer diameter equal to that of the cylindrical member E and a larger inner diameter at one end of the cylindrical member E; a step of forming a second tubular member having a male thread at the tip thereof having a diameter smaller than the inner diameter of the cylindrical body F to be screwed into the male thread of the first tubular member; A step of assembling the second tubular member by screwing it through the second tubular member, holding the center and creating a gap, a step of forming an insulating material made of glass powder and mica powder into a cylindrical preform, and the above assembly. heating the first tubular member, the second tubular member, the preform, and the molding die to respective predetermined temperatures;
A step of arranging an external molding mold around the outer periphery of the first tubular member and the second tubular member assembled in a heated state, and a step of placing an external molding mold on the outer periphery of the first tubular member and the second tubular member assembled in a heated state, and in a space formed by the cylinder body B of the first tubular member and the molding mold. A process of loading the preform, a process of pressurizing the preform and filling it into the gap formed by the first tubular member and the second tubular member to form an insulator, and removing the cylinder B by machining. A method for producing an insulated connection device for piping, which comprises the steps of processing the inner circumferential surface, removing the cylinder D and exposing the insulator, and installing a connecting screw on the inner circumferential surface.