Apparatus and method for conducting seawater pressure tests using carbon steel pressure vessels

Abstract

This invention discloses an apparatus and method for conducting seawater pressure tests using a carbon steel pressure vessel. The apparatus includes a carbon steel pressure cylinder, a titanium alloy pressure cylinder, a test specimen, seawater, and fresh water. The titanium alloy pressure cylinder is disposed inside the carbon steel pressure cylinder. The test specimen is disposed inside the titanium alloy pressure cylinder. Seawater fills the interior of the titanium alloy pressure cylinder. Fresh water fills the space between the inner wall of the carbon steel pressure cylinder and the outer wall of the titanium alloy pressure cylinder. This invention discloses an apparatus and method for conducting seawater pressure tests using a carbon steel pressure vessel. The titanium alloy pressure cylinder is reusable and highly corrosion-resistant, while the carbon steel pressure cylinder remains in contact with fresh water. This is a safe, reliable, and low-cost seawater pressure testing apparatus.

Description

Technical Field

[0001] This invention relates to the technical field of seawater pressure testing methods, and in particular to an apparatus and method for conducting seawater pressure tests using a carbon steel pressure vessel. Background Technology

[0002] Traditional large-size pressure vessels, both domestically and internationally, are mostly made of materials such as carbon steel and low-alloy steel, which are not resistant to seawater corrosion. They are generally used for pressure testing in freshwater media. As humanity ventures deeper into the ocean and explores the seabed more extensively, long-term seawater pressure tests are necessary to effectively simulate the safety of pressure vessels in deep-sea environments. However, current carbon steel and low-alloy steel pressure vessels are not capable of directly undergoing seawater pressure testing because carbon steel and low-alloy steel have poor corrosion resistance and will rapidly corrode and fail in seawater, damaging the pressure vessel and even causing test safety accidents.

[0003] To conduct seawater pressure tests, it is necessary to modify the carbon steel pressure cylinder for corrosion protection or construct a new pressure vessel using corrosion-resistant materials. In engineering, a low-cost carbon steel solution can also be achieved through carbon steel with coatings / sacrificial anode corrosion protection. Generally, corrosion protection can be achieved by coating with anti-corrosion paint or by welding with corrosion-resistant alloys. However, the quality of anti-corrosion paint application cannot be fully guaranteed; once damaged, the damaged area will experience pitting corrosion at a high rate, increasing the safety risk of the test. While welding with corrosion-resistant alloys is a costly and time-consuming process, the quality of the weld at corners is difficult to guarantee. Once the carbon steel substrate is exposed, it will corrode even faster under the galvanic action of the corrosion-resistant alloy.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a device for conducting seawater pressure tests using a carbon steel pressure vessel. Its titanium alloy pressure cylinder is reusable and highly corrosion-resistant, while the carbon steel pressure cylinder still comes into contact with fresh water. It is a safe, reliable, and low-cost seawater pressure test device.

[0006] Another object of the present invention is to provide a method for conducting seawater pressure tests using a carbon steel pressure vessel.

[0007] To achieve the above objectives, the present invention provides an apparatus for conducting seawater pressure tests using a carbon steel pressure vessel, comprising a carbon steel pressure cylinder, a titanium alloy pressure cylinder, a test specimen, seawater, and fresh water; the titanium alloy pressure cylinder is disposed inside the carbon steel pressure cylinder; the test specimen is disposed inside the titanium alloy pressure cylinder; seawater fills the interior of the titanium alloy pressure cylinder; and fresh water fills the space between the inner wall of the carbon steel pressure cylinder and the outer wall of the titanium alloy pressure cylinder.

[0008] In a preferred embodiment, the dimensions of the titanium alloy pressure cylinder are all more than 20% smaller than those of the carbon steel pressure cylinder.

[0009] In a preferred embodiment, the titanium alloy pressure cylinder has a wall thickness of not less than 10 mm, and the material is TA2 or TC4 titanium alloy.

[0010] In a preferred embodiment, the apparatus for conducting seawater pressure tests using a carbon steel pressure vessel further includes water plugs, which are respectively installed at the water inlets of the carbon steel pressure cylinder and the titanium alloy pressure cylinder.

[0011] In a preferred embodiment, the water plug is made of carbon steel, low alloy steel, or titanium alloy.

[0012] In a preferred embodiment, when the water plug is made of carbon steel or low alloy steel, the part of the water plug that comes into contact with seawater needs to be protected against corrosion.

[0013] To achieve the aforementioned other objective, the present invention also provides a method for conducting seawater pressure tests using a carbon steel pressure vessel, applied to the aforementioned apparatus. The method includes: first, placing the test specimen inside a titanium alloy pressure cylinder, and injecting seawater into the titanium alloy pressure cylinder through its inlet, filling the space between the inner wall of the titanium alloy pressure cylinder and the test specimen; then, blocking the inlet of the titanium alloy pressure cylinder with a water plug; second, injecting fresh water into the carbon steel pressure cylinder through its inlet, filling the space between the inner wall of the carbon steel pressure cylinder and the outer wall of the titanium alloy pressure cylinder with fresh water; then, blocking the inlet of the carbon steel pressure cylinder with a water plug; third, pressurizing the fresh water, maintaining the pressure for a certain period after each pressurization, then further pressurizing and maintaining the pressure for another period, until the pressure reaches a set value and is maintained for a set time; and fourth, pressurizing the seawater, maintaining the pressure for a certain period after each pressurization, then further pressurizing and maintaining the pressure for another period, until the pressure reaches a set value and is maintained for a set time.

[0014] In a preferred embodiment, the pressure applied to the fresh water and seawater each time is 1 MPa, and the pressure is maintained for a period of 1 min to 5 min.

[0015] In a preferred embodiment, the maximum pressure applied to fresh water and seawater does not exceed the design pressure of the carbon steel pressure cylinder and the titanium alloy pressure cylinder.

[0016] In a preferred embodiment, the seawater is 3.5% artificial seawater.

[0017] Compared with existing technologies, the apparatus and method for conducting seawater pressure tests using carbon steel pressure vessels of the present invention have the following advantages: the titanium alloy cylinder of this application can be moved and reused in multiple carbon steel pressure vessels, reducing usage costs; the carbon steel pressure vessel is always in contact with fresh water, eliminating the risk of corrosion and ensuring safety and reliability; pressure can be applied both inside and outside the titanium alloy cylinder, improving the safety of the test. This experimental apparatus, which uses a titanium alloy cylinder as an intermediate layer between the test specimen and the carbon steel pressure vessel, fills the space between the carbon steel pressure vessel and the titanium alloy cylinder with fresh water and the space between the titanium alloy cylinder and the test specimen with seawater; by applying pressure both inside and outside the titanium alloy cylinder, it ensures the pressure rating of the test specimen and enhances the pressure safety of the titanium alloy cylinder. It is a safe, reliable, and low-cost seawater pressure testing apparatus and method, suitable for widespread application. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of an experimental apparatus according to an embodiment of the present invention;

[0019] Figure 2 This is a flowchart of an experimental method according to an embodiment of the present invention.

[0020] Explanation of key figure labels:

[0021] 1-Carbon steel pressure cylinder, 2-Titanium alloy pressure cylinder, 3-Test specimen. Detailed Implementation

[0022] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0023] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0024] like Figure 1 As shown, an apparatus for conducting seawater pressure tests using a carbon steel pressure vessel according to a preferred embodiment of the present invention includes a carbon steel pressure cylinder 1, a titanium alloy pressure cylinder 2, a test specimen 3, seawater, and fresh water; the titanium alloy pressure cylinder 2 is disposed inside the carbon steel pressure cylinder 1; the test specimen 3 is disposed inside the titanium alloy pressure cylinder 2; seawater fills the interior of the titanium alloy pressure cylinder 2; and fresh water fills the space between the inner wall of the carbon steel pressure cylinder 1 and the outer wall of the titanium alloy pressure cylinder 2.

[0025] In some embodiments, the dimensions of the titanium alloy pressure cylinder 2 are all more than 20% smaller than those of the carbon steel pressure cylinder 1. The carbon steel pressure cylinder 1 and the titanium alloy pressure cylinder 2 may have the same or different shapes, for example, but not limited to, rectangular cylinders, cylindrical cylinders, etc.

[0026] In some embodiments, the wall thickness of the titanium alloy pressure cylinder 2 is not less than 10 mm, and the material used is TA2 or TC4 titanium alloy. The wall thickness of the carbon steel pressure cylinder 1 can be determined according to the actual size and the required design pressure value, for example, it is not limited to but not less than 10 mm.

[0027] In some embodiments, the apparatus for conducting seawater pressure tests using carbon steel pressure vessels also includes water plugs, which are respectively installed at the water inlets of the carbon steel pressure cylinder 1 and the titanium alloy pressure cylinder 2.

[0028] In some implementations, the water plug is made of carbon steel, low-alloy steel, or titanium alloy.

[0029] In some implementations, when the water plug is made of carbon steel or low-alloy steel, the portion of the water plug in contact with seawater requires corrosion protection. This corrosion protection can be, but is not limited to, using AMGT-9 type aluminum alloy sacrificial anode corrosion protection on the seawater-contacting parts.

[0030] like Figure 2 As shown, according to a preferred embodiment of the present invention, a method for conducting seawater pressure tests using a carbon steel pressure vessel, applied to the aforementioned apparatus, includes: firstly, placing the test specimen 3 inside a titanium alloy pressure cylinder 2, and injecting seawater into the titanium alloy pressure cylinder 2 through its inlet, filling the space between the inner wall of the titanium alloy pressure cylinder 2 and the test specimen 3 with seawater, and then blocking the inlet of the titanium alloy pressure cylinder 2 with a water plug; secondly, injecting fresh water into a carbon steel pressure cylinder 1 through its inlet, filling the space between the inner wall of the carbon steel pressure cylinder 1 and the outer wall of the titanium alloy pressure cylinder 2 with fresh water, and then blocking the inlet of the carbon steel pressure cylinder 1 with a water plug; thirdly, pressurizing the fresh water, maintaining the pressure for a certain period of time after each pressurization, and then pressurizing it again for a certain period of time, until the pressure reaches a set value and is maintained for a set time; and fourthly, pressurizing the seawater, maintaining the pressure for a certain period of time after each pressurization, and then pressurizing it again for a certain period of time, until the pressure reaches a set value and is maintained for a set time.

[0031] In some implementations, the fresh water and seawater are pressurized by a certain value of 1 MPa each time, and the pressure is maintained for a period of 1 min to 5 min.

[0032] In some implementations, the maximum pressure applied to fresh water and seawater does not exceed the design pressure of the carbon steel pressure cylinder 1 and the titanium alloy pressure cylinder 2.

[0033] In some implementations, the seawater is 3.5% artificial seawater.

[0034] In some embodiments, the method of conducting seawater pressure tests using a carbon steel pressure cylinder 1 according to the present invention is illustrated below by example:

[0035] (1) A titanium alloy cylinder is used as the intermediate layer between the test specimen 3 and the carbon steel pressure cylinder 1. The outer diameter of the titanium alloy cylinder is 50% of the inner diameter of the carbon steel pressure cylinder 1, and the height is 30% of the depth of the carbon steel pressure cylinder 1. The titanium alloy material is TC4, and the wall thickness of the titanium alloy cylinder is 12mm.

[0036] (2) First, place the test specimen 3 into the titanium alloy cylinder, then fill the space between the test specimen 3 and the titanium alloy cylinder with 3.5% artificial seawater, then seal the titanium alloy cylinder with a carbon steel plug and place it into the carbon steel pressure cylinder 1. Finally, fill the carbon steel container with fresh water and close the carbon steel pressure cylinder 1. Use AMGT-9 type aluminum alloy sacrificial anode to protect the inside of the plug (i.e., the part in contact with seawater) to avoid excessive corrosion of the plug.

[0037] (3) By pressurizing both the inside and outside of the titanium alloy cylinder, the pressure rating of the test specimen 3 is guaranteed, and the pressure safety of the titanium alloy cylinder is enhanced. During pressurization, fresh water is pressurized first, and the pressure is maintained for 3 minutes for every 1 MPa pressurized, until the pressure reaches 3 MPa; then seawater is pressurized, and the pressure is maintained for 3 minutes for every 1 MPa pressurized, until the pressure reaches 3 MPa.

[0038] In summary, the apparatus and method for conducting seawater pressure tests using a carbon steel pressure vessel of the present invention have the following beneficial effects: the titanium alloy cylinder of this application can be moved and reused in multiple carbon steel pressure vessels, reducing usage costs; the carbon steel pressure vessel is always in contact with fresh water, eliminating the risk of corrosion and ensuring safety and reliability; pressure can be applied both inside and outside the titanium alloy cylinder, improving the safety of the test. This experimental apparatus, which uses a titanium alloy cylinder as an intermediate layer between the test specimen and the carbon steel pressure vessel, fills the space between the carbon steel pressure vessel and the titanium alloy cylinder with fresh water and the space between the titanium alloy cylinder and the test specimen with seawater; by applying pressure both inside and outside the titanium alloy cylinder, it ensures the pressure rating of the test specimen and enhances the pressure safety of the titanium alloy cylinder. It is a safe, reliable, and low-cost seawater pressure testing apparatus and method suitable for widespread application.

[0039] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. An apparatus for conducting seawater pressure tests using a carbon steel pressure vessel, characterized in that, include: Carbon steel pressure cylinder; A titanium alloy pressure cylinder is disposed inside the carbon steel pressure cylinder; The test specimen is disposed inside the titanium alloy pressure cylinder; Seawater, which fills the interior of the titanium alloy pressure cylinder; and Fresh water fills the space between the inner wall of the carbon steel pressure cylinder and the outer wall of the titanium alloy pressure cylinder.

2. The apparatus for conducting seawater pressure tests using a carbon steel pressure vessel as described in claim 1, characterized in that, The dimensions of the titanium alloy pressure cylinder are all more than 20% smaller than those of the carbon steel pressure cylinder.

3. The apparatus for conducting seawater pressure tests using a carbon steel pressure vessel as described in claim 1, characterized in that, The titanium alloy pressure cylinder has a wall thickness of not less than 10mm, and the material used is TA2 or TC4 titanium alloy.

4. The apparatus for conducting seawater pressure tests using a carbon steel pressure vessel as described in claim 1, characterized in that, It also includes water plugs, which are respectively installed at the water inlets of the carbon steel pressure cylinder and the titanium alloy pressure cylinder.

5. The apparatus for conducting seawater pressure tests using a carbon steel pressure vessel as described in claim 4, characterized in that, The water plug is made of carbon steel, low alloy steel, or titanium alloy.

6. The apparatus for conducting seawater pressure tests using a carbon steel pressure vessel as described in claim 5, characterized in that, When the water plug is made of carbon steel or low alloy steel, the part of the water plug that comes into contact with seawater needs to be protected against corrosion.

7. A method for conducting seawater pressure tests using a carbon steel pressure vessel, applied to the apparatus as described in any one of claims 1 to 6, characterized in that, The method includes: First, place the test specimen inside the titanium alloy pressure cylinder, and inject seawater into the cylinder through the water inlet to fill the space between the inner wall of the cylinder and the test specimen. Then, block the water inlet of the cylinder with a water plug. Fresh water is injected into the carbon steel pressure cylinder through its water inlet, filling the space between the inner wall of the carbon steel pressure cylinder and the outer wall of the titanium alloy pressure cylinder. Then, the water inlet of the carbon steel pressure cylinder is blocked with a water plug. First, the fresh water is pressurized, and after each pressurization to a certain value, it is maintained for a certain period of time. This process is repeated until the pressure reaches the set value and is maintained for the set time. Then the seawater is pressurized, and after each pressurization, it is maintained for a certain period of time. Then the pressurization is increased again and maintained for a certain period of time, until the pressure reaches the set value and is maintained for the set time.

8. The method for conducting seawater pressure tests using a carbon steel pressure vessel as described in claim 7, characterized in that, Each time, the fresh water and seawater are pressurized to a certain value of 1 MPa and maintained for a period of 1 to 5 minutes.

9. The method for conducting seawater pressure tests using a carbon steel pressure vessel as described in claim 7, characterized in that, The maximum pressure applied to fresh water and seawater shall not exceed the design pressure of the carbon steel pressure cylinder and the titanium alloy pressure cylinder.

10. The method for conducting seawater pressure tests using a carbon steel pressure vessel as described in claim 7, characterized in that, The seawater in question is 3.5% artificial seawater.

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