JP2001074624A - External pressure load test equipment for steel pipes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightweight and compact external pressure load test apparatus with a simpler fastening structure without lowering the outer surface sealing function of the external pressure load test apparatus for steel pipes. In an external pressure load test apparatus in which an end of a test steel pipe (4) projects outside a pressure vessel (1), a test is performed in which the inside of both ends of a pressure vessel (1) formed of a thick cylinder and the outer surface of the test steel pipe (4) are sealed inside. A first seal portion is formed with an O-ring in a gap between the outer surface of a pair of packing holder-equipped lids 2 also functioning as a packing holder having a steel pipe outer surface sealing packing 9 and a flange and having a pressure vessel end. An external pressure load test apparatus for a test steel pipe 4 in which a U-packing 5 is inserted into an inner corner portion to form a second seal portion, and the lid 2 is fastened to an end of the pressure vessel 1 with a high-strength bolt 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel pipe external pressure load test apparatus for performing a test by applying an external pressure to a steel pipe such as a pipe or a pipe joint.

[0002]

2. Description of the Related Art A steel pipe such as a pipe or a pipe joint is subjected to an external pressure test by applying a high pressure to the outside of an external pressure load test apparatus. As an external pressure load test apparatus, as a means for releasing the action of the pipe end axial force at the time of pressure load, which cannot be avoided in the conventional sealed steel pipe external pressure test, for example, as shown in JP-B-56-48819, In addition, a tube end outer surface sealing mechanism is employed.

FIG. 3 is a sectional view of a conventional external pressure load test apparatus provided with an external sealing mechanism.

At both ends of the pressure vessel 30, an external pressure water supply port 31 for supplying high pressure water to the pressure vessel 30 and an air vent port 32 for releasing air when supplying high pressure water are provided. At both ends of the pressure vessel 30, lids 33 are provided.
Are fastened by a hydraulic clamp 34.

[0005] The test steel pipe 35 is held down by an outer packing holder 36. The outer packing retainer 36 is provided with a packing 38 with a metal ring for pressing against the test steel pipe 35 with the pressure water from the seal pressure water port 37 to seal the gap between the pressure vessel 30 and the test steel pipe 35. I have.

[0006] The features of the conventional external pressure load test apparatus are (1)
Special packing is used to seal the steel pipe from the outer circumference. (2) U-packing with metal ring is used to seal the pressure vessel body and the pipe end cover. (3) Hydraulic clamping of the pressure vessel and the cover The structure is such that it is automatically and firmly fastened by a mechanism. The apparatus has been used by many steel pipe manufacturers for many years because of its functionality of performing a pure external pressure test without having to consider the adverse effect of axial force on the test results, and its operability and soundness of the seal.

[0007]

The conventional external pressure load test apparatus is designed mainly to efficiently perform a steel pipe crush test of a wide range of outer diameters at a manufacturing site, so that the entire apparatus is large in size. Has become. However, in recent technological developments for oil country tubular goods, the use of applying external pressure to a gas leak test of a threaded joint rather than crushing of a steel pipe body to confirm the performance thereof has been increasing. Therefore, there is a growing need for a compact pressure vessel that can be attached to a test steel pipe as an accessory rather than a large and fixed type pressure vessel. In such a case, the clamp structure for fastening the lid and the pressure vessel of the conventional external pressure load test apparatus is too heavy and needs to be improved in order to utilize and spread such new uses.

According to the present invention, the outer surface sealing function of the steel pipe external pressure load test apparatus is maintained as in the prior art, and the fastening structure is simplified, lightened, without lowering the sealing ability between the pressure vessel and the lid. It is intended to provide a compact external pressure load test device.

[0009]

According to the present invention, there is provided an external pressure load test apparatus for a test steel pipe, wherein an end of the test steel pipe protrudes out of the pressure vessel. An O-ring is provided in the gap between the outer surface of a pair of lids having a packing holder and a lid having a flange and a packing holder in which a test steel pipe outer surface seal packing for sealing the outer surface of the test steel pipe is sealed inside. Forming a first seal portion, inserting a U-packing into a pressure vessel end inner surface corner portion to form a second seal portion, and fastening the lid to the pressure vessel end portion with a high-strength bolt. And

[0010] In the above-mentioned configuration, a wide flap may be attached to the end of the pressure vessel to suppress the expansion of the end of the pressure vessel by the test pressure load and to prevent the opening of the contact portion between the pressure vessel and the lid.

A hydraulic cylinder is provided on the outer periphery of the pressure vessel so that the tip of a piston rod advances and retreats to the center of the pressure vessel, and the inlet of the piston rod of the pressure vessel has a ring-shaped groove inside which a rod outer surface seal packing can be set. And a packing retainer may be attached.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention takes advantage of the features of (1) and (2), which are features of a conventional external pressure load test apparatus,
(3) The lid is directly bolted to the end face of the pressure vessel to fasten the lid to the pressure vessel, thereby eliminating the strong but heavy clamping structure of the conventional apparatus and reducing the outer diameter of the vessel. Things. The pressure vessel is
In order to reduce the size of the forged material and simplify the machining, the shape is close to that of a thick cylinder to give as high a pressure resistance as possible with the same weight. If the external pressure load test device is designed based on the above guidelines, the following technical problems must be solved.

[0013] Compared to the existing large-sized external pressure load test apparatus, the lid is simplified, so that the mechanical rigidity against the internal pressure at the inner end of the pressure vessel is insufficient (radial displacement of the inner diameter of the pressure vessel due to the test pressure load). The clearance at the boundary between the pressure vessel and the lid increases, and the internal high water pressure sealing function decreases. In addition, in order to ensure the safety of bolt fastening in place of the hydraulic clamp, it is necessary to select the number of bolts, strength, and diameter, and to properly manage the tightening of bolts so that there is no gap between the end of the pressure vessel and the lid flange. .

To make up for the former lack of rigidity, the following configuration is adopted.

A. An O-ring with backup is applied to the lid and the inlay on the inner surface of the pressure vessel end. For application, refer to a known document (“Experimental study on characteristics of pressure vessel seal using rubber O-ring”, JHPI Vo)
l. 20 No. 6 1982), the fitting is performed with a clearance fit (holes H7-8, shafts f7-8; maximum clearance 80 μm).
m) to prevent the O-ring from biting out due to the high pressure action. In the above structure, since the fastening structure is strong, it is not necessary to provide the second high-pressure seal portion on the inlay portion, and it is sufficient to achieve a seal capable of forming an outer surface pre-seal (20 atm) of the test steel pipe. Although the ring is inserted, the gap may be 100 μmm to 200 μmm. Originally,
If an O-ring with a backup ring is inserted therein, the lid does not easily enter the pressure vessel and the O-ring is also easily damaged, which causes problems in terms of function and operation, which is not good.
An O-ring or the like is generally applied to a non-sliding butted portion such as a flange. However, in the present invention, when high-pressure water enters the inside of the flange portion of the lid, the pressure received by the lid increases and the gap between the flange portions is easily formed. It will open. Therefore, in the present structure, the gap of the spigot part is intentionally narrowed, and an O-ring or an O-ring with a back-up ring is mounted thereon. The problem with the O-ring damage is that when the lid is assembled, two sufficiently long guide bolts are screwed into the end of the pressure vessel in advance, and the lid is inserted along it, so that the center of the narrow gap can be inserted properly. I try to go. By doing so, the lid can be smoothly incorporated into the pressure vessel even under severe fitting conditions without twisting or damaging the O-ring or the backup ring.

B. In order to minimize the expansion of the pressure vessel end at the test pressure load, which has a significant effect on the sealing part of the lid and the lid at the pressure vessel end, in the final stage of assembling the equipment, the effect of the tag on the outside of the pressure vessel end should be sufficient. A steel reinforcing ring with a wide brim that can be used is fitted.

C. The inner diameter of the pressure vessel must be larger at the end than the outer diameter of the bush of the lid on which the outer seal packing of the test pipe is installed, but the outer diameter of the test pipe is deformed by the external pressure at the center of the pressure vessel. At this time, as long as the clearance for avoiding interference is secured, it is preferable that the pressure vessel is small in terms of rigidity. Therefore, the entire inner surface of the pressure vessel has a shape in which the central portion is expanded as seen in the embodiment. .

Next, the following points are taken into consideration in order to ensure the safety of the latter bolt fastening. a. The number, diameter, and strength of bolts that can withstand the axial load applied to the pressure vessel inner diameter and the pressure receiving part of the intermediate donut-shaped part outside the test steel pipe.

B. Tightening control of bolts so that there is no gap in the bolted part when pressure is applied.

By taking the above into consideration, an intended compact external pressure load test apparatus can be designed. Further, the apparatus of the present invention can test steel pipes of several sizes by replacing the lid with the same pressure vessel. However, in the design of the pressure vessel for multiple sizes, the larger the steel pipe size, the larger the vessel for containing it, of course, that it becomes heavier, and the thrust force applied to the inner pressure receiving portion of the donut-shaped lid becomes the largest in the small diameter size, It is necessary to comprehensively consider the allowable weight of the crane to be used.

[0021]

Embodiment 1 FIG. 1 shows an embodiment of the present invention.
5 "(114.3 mm), 5.5" (139.7 m)
m) is a cross-sectional view of an external pressure load test device capable of applying an external pressure to a 7 ″ (177.8 mm) oil country tubular good.

The pressure vessel 1 is designed to withstand a test pressure of 1000 atm. The inner diameter of the pressure vessel 1 is set to be as thick as possible by making the gap with the test steel pipe 4 small.

In order to compensate for the tendency that the inner diameters at both ends of the pressure vessel 1 become larger and thinner according to the diameter of the spigot part of the lid 2 with the packing holder which also serves as the outer peripheral packing holder, the central part of the pressure vessel 1 is connected to the test steel pipe 4. Inflated inward to the extent that it does not interfere.

The pressure vessel 1 has an external pressure water supply port 16 for supplying high pressure water to the pressure vessel 1, an air release port 15 for releasing air when supplying high pressure water, and a hook used for lifting the pressure vessel 1. 21 are provided.

The test steel pipe 4 is pressed by the outer packing 3. Pressure vessel 1 and lid 2 with packing holder
Packing 5 with metal ring 5a that protects the gap from internal pressure
Is provided. This corresponds to the second seal portion of the first aspect.

The outer periphery of the pressure vessel 1 and the lid 2 with the packing holder are sealed by an O-ring 6 for high-pressure sealing and a backup ring 7, and corresponds to the first sealing part of the first aspect. A hook 21 for lifting is also provided on the outer periphery of the lid 2 with the packing holder.

The seal pressure water port 8 is a pressure vessel 1
In order to seal the gap between the pressure vessel 1 and the test steel pipe 4 using the test steel pipe outer seal packing 9 and the backup ring 9a to fill the inside with water, the test steel pipe outer seal packing 9 is pressed against the test steel pipe. Pressure water supply port for This sealing can be achieved by contracting the outer seal packing 9 of the test steel pipe in the radial direction at a water pressure of 20 atm. O-rings 10 and 11 for sealing and high-pressure sealing are used so that a seal pressure of 20 atm acts only on the outside of the seal packing 9 on the outer surface of the steel pipe under test and does not go outside the pressure vessel 1 or the pressure vessel. The ring 6.

The portion of the high-pressure sealing ring 6 has a clearance fit to withstand the high pressure during the test. O-rings 10 and 11 for sealing are 100 μmm to 200 μm
It is manufactured with a gap of mm. Since high pressure acts on both sides of the sealing O-rings 10 and 11 during the test, there is no fear that the O-rings will bite from one side even if there is a sufficient gap. The packing holder 3 for holding the outer seal packing 9 for the steel pipe under test is fixed to the lid 2 with the packing holder by bolts 12. The lid 2 with the packing holder is fixed to the pressure vessel 1 with high-strength bolts 13.

In this embodiment, a 4.5 ″ oil country tubular goods joint has one
The bolt 12 is made of M3 having a material strength of 110 kg / mm ² so as to withstand the maximum thrust force acting on the lid 2 with the packing holder generated when an external pressure of 000 atm is applied.
Twelve 0JIS standard products were applied. Then, the bolts 12 were tightened and controlled with a torque wrench at 70 to 90 kg · m so that there was no gap between the flange portions of the packing retainer 3 and so as not to be distorted.

When a test pressure of 1000 atm acts on the thin portion at the end of the pressure vessel, the inner diameter of the end of the pressure vessel is widened, so that the sealing function of the first seal portion and the second seal portion is not reduced. For this reason, a flap is fitted to the outside of the pressure vessel by the brim wide ring 14.

In this embodiment, the test steel pipe 4 having a 7 ″ joint is incorporated, but a test of a pipe size of 7 ″ or less is possible in the pressure vessel 1. In that case, the lid 2 with the packing holder, the packing holder 3, and the seal packing 9 for the outer surface of the test steel pipe may be separately prepared.

Next, the procedure from the setting of the test steel pipe to the start of the test will be described.

1) After the test steel pipe 4 is set as shown in FIG. 1, an axial force or torsion is applied to the test steel pipe 4 by the pressure vessel 1.
Load with external hydraulics.

2) Apply a water pressure of 20 atm from the seal pressure water port 8 and press the outer seal packing 9 of the test steel pipe against the test steel pipe.

3) External pressure water is supplied from the external pressure water supply port 16.

4) Vent air from the air vent port 15.

5) High-pressure water is supplied from the seal pressure water port 8 and the external pressure water supply port 16 to make the test pressure. At this time, the seal and the thrust resistance of the lid 2 with the packing holder and the pressure vessel 1 are ensured by the seal structure, the bolt, and the tag.

The conventional external pressure load test device shown in FIG. 3 is a universal test device capable of simultaneously applying external pressure, axial force, and torsion. However, even if such a test device is not owned, even a large tensile test device can be used. If it is owned, the external pressure load test device of the present invention and a small hydraulic pump are newly prepared, and if the external pressure load test device is attached to the steel pipe to be tested, the integral structure can be entirely attached to the frame of the tensile tester. Can be installed, Figure 3
A test equivalent to the conventional external pressure load test apparatus shown in FIG.

Embodiment 2 FIG. 2 shows another embodiment of the present invention, and is a cross-sectional view of an external pressure load test device provided with a bending cylinder rod. The same configuration as the external pressure load test device shown in FIG. With a sign,
The description is omitted.

The external pressure load test apparatus of the present invention has a structure in which the hydraulic cylinder rod 17 is pushed outside the pressure vessel 1. The packing holder 18 can be welded to the outside of the pressure vessel, or if the thickness of the pressure vessel 1 is large, it can be installed by processing the outer periphery of the pressure vessel 1.
The packing 20 for the rod outer surface seal has the same structure as the outer surface seal packing 9 for the steel pipe to be tested.
Hold 9 down.

According to the present embodiment, a test in which a bending load is applied to the test steel pipe by pushing the hydraulic cylinder rod 17 is also possible.

[0042]

The outer surface sealing function of the steel pipe external pressure load test apparatus is maintained as before, and the lid is fastened to the end of the pressure vessel with high-strength bolts without reducing the sealing ability between the pressure vessel and the lid. With this fastening structure, a lightweight and compact external pressure load test device can be obtained.

Further, by providing a piston rod that moves in and out of the pressure vessel in the pressure vessel, a test in which a bending load is applied to the test steel pipe can be performed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an external pressure load test apparatus according to the present invention.

FIG. 2 shows another embodiment of the present invention and is a cross-sectional view of an external pressure load test apparatus provided with a bending cylinder rod.

FIG. 3 is a cross-sectional view of a conventional external pressure load test device.

[Explanation of symbols]

 1: pressure vessel 2: lid with packing holder 3: packing holder 4: test steel pipe 5: U packing 5a: backup ring 6: O-ring for high pressure seal 7: backup ring 8: port for seal pressure water 9: test steel pipe Outer seal packing 9a: Backup ring 10, 11: O-ring for sealing 12: Bolt for holding down packing 13: Bolt for fixing lid 14: Pressure vessel expansion prevention ring 15: Air vent port 16: External pressure water supply port 17: For bending load load Cylinder rod 18: Packing holder 19: Packing presser 20: Packing for rod outer surface seal 21: Hook 30: Pressure vessel 31: External pressure water supply port 32: Air release port 33: Lid 34: Hydraulic clamp 35: Test steel pipe 36: Outer peripheral packing Holder 37: For seal pressure water Over Bok 38: packing

Claims (3)

[Claims] An external pressure load test apparatus in which an end of a test steel pipe protrudes out of a pressure vessel, wherein an outer surface seal of the test steel pipe for sealing the inside of both ends of a pressure vessel formed of a thick cylinder and the outer surface of the test steel pipe inside. A first seal portion is formed by an O-ring in a gap between a pair of packing holder-equipped lids which also function as a lid having a packing holder and a flange having a packing, and a U-shaped seal is formed at a pressure vessel end inner corner. An external pressure load test apparatus for a test steel pipe, wherein a second seal portion is formed by inserting a packing, and the lid is fastened to an end of the pressure vessel with a high-strength bolt. 2. A flap having a wide brim is provided at an end of the pressure vessel to suppress expansion of the end of the pressure vessel by a test pressure load and to prevent a gap opening between a contact portion of the pressure vessel and the lid. Item 2. An external pressure load test apparatus for a steel pipe according to item 1. 3. A packing cylinder having a hydraulic cylinder in which the tip of a piston rod advances and retreats to the center of the pressure vessel on the outer periphery of the pressure vessel, and an inlet of the piston rod of the pressure vessel having an annular groove inside which a rod outer seal packing can be set. The external pressure load test device for a steel pipe according to claim 1 or 2, wherein a gasket and a gasket are attached.