阅读说明：本技术 一种lng船低温管路充惰性气体检测装置及其检测方法 (Detection device and detection method for filling inert gas into low-temperature pipeline of LNG ship ) 是由 李晓龙 陈琰 孙智豪 秦毅 王学宇 刘希权 于 2021-06-30 设计创作，主要内容包括：本发明公开了一种LNG船低温管路充惰性气体检测装置,包括密封装置和气体检测模组；密封装置包括海绵本体和换向阀,海绵本体上设置有取样口,所述换向阀包括阀体,阀体内部设置有第一进气阀腔、第二进气阀腔、出气阀腔和连接流道,第一进气阀腔、第二进气阀腔和出气阀腔之间通过连接流道相连通,所述第一进气阀腔、第二进气阀腔和出气阀腔内均安装有开关阀组,第一进气阀腔内还设置有限位组件。本发明能够对低温管路进行封堵,以便向低温管路内通惰性气体,通入惰性气体的过程中,换向阀可以根据气体流量大小及时切换其进气阀腔,以将低温管路内的残留空气全部排出,避免焊接过程中焊缝被氧化,有效保证焊接质量。(The invention discloses a detection device for filling inert gas into a low-temperature pipeline of an LNG ship, which comprises a sealing device and a gas detection module; the sealing device comprises a sponge body and a reversing valve, a sampling port is arranged on the sponge body, the reversing valve comprises a valve body, a first air inlet valve cavity, a second air inlet valve cavity, an air outlet valve cavity and a connecting flow channel are arranged inside the valve body, the first air inlet valve cavity, the second air inlet valve cavity and the air outlet valve cavity are communicated through the connecting flow channel, a switch valve group is arranged in each of the first air inlet valve cavity, the second air inlet valve cavity and the air outlet valve cavity, and a limiting component is further arranged in each of the first air inlet valve cavity, the second air inlet valve cavity and the air outlet valve cavity. The low-temperature pipeline can be plugged, so that inert gas can be introduced into the low-temperature pipeline, and in the process of introducing the inert gas, the reversing valve can timely switch the gas inlet valve cavity according to the gas flow so as to completely discharge residual air in the low-temperature pipeline, so that the welding seam is prevented from being oxidized in the welding process, and the welding quality is effectively ensured.)

1. The device for detecting the filling of inert gas into the low-temperature pipeline of the LNG ship is characterized by comprising a sealing device and a gas detection module;

the sealing device is used for plugging the low-temperature pipeline and comprises a sponge body and a reversing valve, wherein the sponge body is provided with a sampling port,

the reversing valve comprises a valve body, a first air inlet valve cavity, a second air inlet valve cavity, an air outlet valve cavity and a connecting flow channel are arranged in the valve body, the first air inlet valve cavity, the second air inlet valve cavity and the air outlet valve cavity are communicated through the connecting flow channel, switch valve groups are arranged in the first air inlet valve cavity, the second air inlet valve cavity and the air outlet valve cavity, and a limiting component used for enabling an air inlet of the valve cavity to be in a normally open state is further arranged in the first air inlet valve cavity;

the first air inlet valve cavity and the second air inlet valve cavity of the reversing valve are respectively connected with a sampling port on the sponge body through an air inlet pipe, and the air outlet valve cavity is connected with the gas detection module through an air outlet pipe;

when the flow of the inert gas introduced into the low-temperature pipeline is within a first set flow range, the gas flows to the gas outlet pipe along the first gas inlet valve cavity, the connecting flow channel and the gas outlet valve cavity of the reversing valve and flows into the gas detection module through the gas outlet pipe;

when the flow of the inert gas introduced into the low-temperature pipeline is increased to a second set flow range, the valve switching groups in the first gas inlet valve cavity and the second gas inlet valve cavity move towards the gas outlets of the respective valve cavities under the action of gas pressure, so that the gas outlet of the first gas inlet valve cavity is closed, the gas inlet of the second gas inlet valve cavity is opened, and the gas flows to the gas outlet pipe along the second gas inlet valve cavity, the connecting flow channel and the gas outlet valve cavity and flows into the gas detection module through the gas outlet pipe.

2. The LNG ship low-temperature pipeline inert gas filling detection device according to claim 1, wherein a traction reinforcing component is further arranged on the sealing device, the traction reinforcing component comprises a reinforcing support, traction ropes and a connecting joint, the reinforcing support is embedded in the sponge body, two end portions of the reinforcing support extend out of the side face of the sponge body and are respectively fixed with one traction rope, the two traction ropes are fixed on the connecting joint in an intersecting manner, one end of the connecting joint is connected with the gas outlet valve cavity of the reversing valve through the gas outlet pipe, and the other end of the connecting joint is connected with the gas detection module through the gas pipe.

3. The LNG ship low-temperature pipeline inert gas filling detection device according to claim 1 or 2, wherein the gas detection module comprises a detection joint, a filter, a gas flowmeter, a gas detection device and a spray pipe which are sequentially arranged along a gas flow path, the detection joint, the filter, the gas flowmeter, the gas detection device and the spray pipe are connected through gas pipes, and the detection joint is connected with a reversing valve or a connection joint of a traction reinforcing assembly through the gas pipes.

4. The device for detecting the filling of the inert gas into the LNG carrier low-temperature pipeline according to claim 1 or 3, wherein sealing seats are further arranged among contact positions of the switch valve groups in the first gas inlet valve cavity, the second gas inlet valve cavity and the gas outlet valve cavity and the valve cavities of the switch valve groups.

5. The device for detecting the filling of the inert gas into the LNG carrier low-temperature pipeline according to claim 4, wherein the valve groups in the first gas inlet valve cavity, the second gas inlet valve cavity and the gas outlet valve cavity have the same structure and respectively comprise a spring and a valve core fixedly connected with the spring;

the elasticity of the spring in the first air inlet valve cavity is smaller than that of the spring in the second air inlet valve cavity, and the elasticity of the spring in the air outlet valve cavity is equal to that of the spring in the first air inlet valve cavity.

6. The device for detecting the filling of inert gas into the LNG ship cryogenic line of claim 1, characterized in that the limiting component comprises a limiting seat fixedly connected with the valve body, a threaded seat fixed in the limiting seat, and an adjusting rod fixed in the threaded seat, and the bottom of the adjusting rod extends out of the threaded seat and abuts against the switch valve group of the first gas inlet valve cavity.

7. The LNG ship cryogenic line inert gas filling detection device of claim 6, wherein the limiting seat comprises a tubular seat body and seat rings uniformly arranged in the tubular seat body, and the seat rings are arranged along a radial direction of the tubular seat body.

8. The LNG ship cryogenic line inert gas filling detection device of claim 1 or 9, wherein the sponge body is further wrapped with a layer of sealing insulation material.

9. The detection method for the detection device for the filling of the LNG ship with the inert gas in the cryogenic pipeline is characterized by comprising the following steps:

s1, debugging the reversing valve to ensure that each valve cavity can be normally opened and closed within a corresponding flow range;

s2, presetting the sealing device behind one welding seam in the low-temperature pipeline, and keeping the sampling port on the sponge body horizontal;

s3, filling inert gas into the pipeline from the gas inlet of the low-temperature pipeline, and when the oxygen meter detects that the oxygen concentration in the gas discharged from the welding seam is not more than 2%, covering the welding seam groove with an adhesive tape for sealing;

s4, continuously filling inert gas into the low-temperature pipeline, when the flow of the introduced inert gas is within a second set flow range, opening a second gas inlet valve cavity and a gas outlet valve cavity of the reversing valve, closing a first gas inlet valve cavity, enabling the gas to flow to the gas outlet pipe along the first gas inlet valve cavity, the connecting flow channel and the gas outlet valve cavity of the reversing valve, enabling the gas to flow into the gas detection module through the gas outlet pipe, and detecting the oxygen concentration in the gas through the gas detection device to ensure that most residual air is discharged;

and S5, reducing the flow of the inert gas, closing the second gas inlet valve cavity of the reversing valve, opening the first gas inlet valve cavity and the gas outlet valve cavity when the flow of the inert gas is within a first set flow range, allowing the gas to flow to the gas outlet pipe along the first gas inlet valve cavity, the connecting flow channel and the gas outlet valve cavity of the reversing valve, allowing the gas to flow into the gas detection module through the gas outlet pipe, starting welding when the gas detection device detects that the oxygen concentration in the gas is zero, and maintaining the flow of the inert gas at the current flow during welding.

10. The method for detecting the filling of the LNG ship cryogenic pipeline with the inert gas as claimed in claim 9, further comprising a step 6 after the step 5: and (4) dragging and moving the sealing device to the rear of the next welding line by using the traction strengthening assembly, and then repeating the step (3), the step (4) and the step (5) until the welding line welding is completed.

Technical Field

The invention relates to the technical field of ship construction, in particular to a detection device and a detection method for filling inert gas into a low-temperature pipeline of an LNG ship.

Background

The LNG ship low-temperature pipeline is an important component of the whole low-temperature system, and plays a role in conveying liquefied natural gas (-163 ℃), and the pipeline is arranged in a horizontal state along a deck surface of a dome of the LNG ship.

The low-temperature pipelines are arranged in a mode of sequentially connecting from the head end to the tail end one by one, and the pipe fittings are fixed by iron-embedded spot welding.

Because the low-temperature pipeline is made of low-temperature austenitic stainless steel, the material is extremely easy to oxidize in the welding process to directly generate welding defects, and any tiny defect can cause the low-temperature pipeline to break in the use process and cause natural gas leakage, so that the generated consequence is unreasonable.

Therefore, before welding the low-temperature pipeline, sealing tools such as sponge and the like are required to be arranged behind the welding line for plugging the pipeline at a certain distance, and inert gas (pipeline inerting for short) is filled into the pipeline from the end part of the pipeline after plugging is finished. The inert gas in the low-temperature pipeline is argon gas with a large specific gravity generally according to the welding requirement, the content of the inert gas needs to reach a standard concentration of not less than 98%, and air (oxygen) is discharged from a groove gap (a coated adhesive tape is torn) of a welding seam so as to ensure that the welding seam is not oxidized in the welding process, as shown in fig. 8.

At present, when a pipeline is inerted, whether the inerting of the pipeline meets requirements is generally judged by measuring the oxygen content in air exhausted from a gap of a groove of a welding seam, and when an oxygen meter detects that the oxygen content is less than 2%, welding operation can be carried out. The continuous supply of inert gas is required during the welding process to maintain the inert gas content inside the tube. However, the length of the low-temperature pipeline with the DN being more than or equal to 300mm is long, the pipeline system arrangement (branch pipes and equipment interfaces) and the pipeline trend (up-down bending and left-right bending) are various, air and residual air inside the pipeline cannot be rapidly discharged in the actual inflation process, some air can be remained and accumulated inside the pipeline, the residual air is mainly concentrated between the welding line and the sealing tool along with inflation, as shown in fig. 9, because the residual air cannot be discharged, the content of inert gas at the position of the welding line cannot be guaranteed, and the production progress can be greatly influenced. Meanwhile, because residual air cannot be discharged, the quality of the welding seam can be directly influenced along with the continuous spread of the inert gas to the position of the welding seam in the welding process.

Disclosure of Invention

In view of the above, the present invention provides a detecting device and a detecting method for detecting inert gas filled in a low temperature pipeline of an LNG ship, so as to solve the problems in the background art.

A detection device for filling inert gas into a low-temperature pipeline of an LNG ship comprises a sealing device and a gas detection module;

the sealing device is used for plugging the low-temperature pipeline and comprises a sponge body and a reversing valve, wherein the sponge body is provided with a sampling port,

the reversing valve comprises a valve body, a first air inlet valve cavity, a second air inlet valve cavity, an air outlet valve cavity and a connecting flow channel are arranged in the valve body, the first air inlet valve cavity, the second air inlet valve cavity and the air outlet valve cavity are communicated through the connecting flow channel, switch valve groups are arranged in the first air inlet valve cavity, the second air inlet valve cavity and the air outlet valve cavity, and a limiting component used for enabling an air inlet of the valve cavity to be in a normally open state is further arranged in the first air inlet valve cavity;

the first air inlet valve cavity and the second air inlet valve cavity of the reversing valve are respectively connected with a sampling port on the sponge body through an air inlet pipe, and the air outlet valve cavity is connected with the gas detection module through an air outlet pipe;

when the flow of the inert gas introduced into the low-temperature pipeline is within a first set flow range, the gas flows to the gas outlet pipe along the first gas inlet valve cavity, the connecting flow channel and the gas outlet valve cavity of the reversing valve and flows into the gas detection module through the gas outlet pipe;

when the flow of the inert gas introduced into the low-temperature pipeline is increased to a second set flow range, the valve switching groups in the first gas inlet valve cavity and the second gas inlet valve cavity move towards the gas outlets of the respective valve cavities under the action of gas pressure, so that the gas outlet of the first gas inlet valve cavity is closed, the gas inlet of the second gas inlet valve cavity is opened, and the gas flows to the gas outlet pipe along the second gas inlet valve cavity, the connecting flow channel and the gas outlet valve cavity and flows into the gas detection module through the gas outlet pipe.

Preferably, the sealing device is further provided with a traction reinforcing component, the traction reinforcing component comprises a reinforcing support, traction ropes and a connecting joint, the reinforcing support is embedded in the sponge body, two end portions of the reinforcing support extend out of the side face of the sponge body and are fixed with one traction rope respectively, the two traction ropes are fixed on the connecting joint in an intersecting manner, one end of the connecting joint is connected with the gas outlet valve cavity of the reversing valve through the gas outlet pipe, and the other end of the connecting joint is connected with the gas detection module through the gas pipe.

Preferably, the gas detection module includes detection joint, filter, gas flowmeter, gaseous detection device and the spray tube that sets gradually along the flow path of gas, links to each other through the trachea between detection joint, filter, gas flowmeter, gaseous detection device and the spray tube, and detection joint passes through the trachea and links to each other with the connector of switching-over valve or traction enhancement subassembly.

Preferably, sealing seats are further arranged between the switching valve groups in the first air inlet valve cavity, the second air inlet valve cavity and the air outlet valve cavity and contact positions of the respective valve cavities.

Preferably, the first air inlet valve cavity, the second air inlet valve cavity and the air outlet valve cavity have the same structure of the switch valve group, and each switch valve group comprises a spring and a valve core fixedly connected with the spring;

the elasticity of the spring in the first air inlet valve cavity is smaller than that of the spring in the second air inlet valve cavity, and the elasticity of the spring in the air outlet valve cavity is equal to that of the spring in the first air inlet valve cavity.

Preferably, the limiting assembly comprises a limiting seat fixedly connected with the valve body, a threaded seat fixed in the limiting seat, and an adjusting rod fixed in the threaded seat, and the bottom of the adjusting rod extends out of the threaded seat and abuts against the switch valve group of the first air inlet valve cavity.

Preferably, the limiting seat comprises a tubular seat body and a seat ring uniformly arranged in the tubular seat body, and the seat ring is arranged along the radial direction of the tubular seat body.

Preferably, the sponge body is further wrapped with a layer of sealing insulating material.

A detection method of a detection device for filling inert gas into a low-temperature pipeline of an LNG ship specifically comprises the following steps:

s1, debugging the reversing valve to ensure that each valve cavity can be normally opened and closed within a corresponding flow range;

s2, presetting the sealing device behind one welding seam in the low-temperature pipeline, and keeping the sampling port on the sponge body horizontal;

s3, filling inert gas into the pipeline from the gas inlet of the low-temperature pipeline, and when the oxygen meter detects that the oxygen concentration in the gas discharged from the welding seam is not more than 2%, covering the welding seam groove with an adhesive tape for sealing;

s4, continuously filling inert gas into the low-temperature pipeline, when the flow of the introduced inert gas is within a second set flow range, opening a second gas inlet valve cavity and a gas outlet valve cavity of the reversing valve, closing a first gas inlet valve cavity, enabling the gas to flow to the gas outlet pipe along the first gas inlet valve cavity, the connecting flow channel and the gas outlet valve cavity of the reversing valve, enabling the gas to flow into the gas detection module through the gas outlet pipe, and detecting the oxygen concentration in the gas through the gas detection device to ensure that most residual air is discharged;

and S5, reducing the flow of the inert gas, closing the second gas inlet valve cavity of the reversing valve, opening the first gas inlet valve cavity and the gas outlet valve cavity when the flow of the inert gas is within a first set flow range, allowing the gas to flow to the gas outlet pipe along the first gas inlet valve cavity, the connecting flow channel and the gas outlet valve cavity of the reversing valve, allowing the gas to flow into the gas detection module through the gas outlet pipe, starting welding when the gas detection device detects that the oxygen concentration in the gas is zero, and maintaining the flow of the inert gas at the current flow during welding.

Preferably, step 5 is followed by step 6: and (4) dragging and moving the sealing device to the rear of the next welding line by using the traction strengthening assembly, and then repeating the step (3), the step (4) and the step (5) until the welding line welding is completed.

The invention has the beneficial effects that:

the low-temperature pipeline can be plugged, so that inert gas can be introduced into the low-temperature pipeline, the reversing valve can timely switch the gas inlet valve cavity according to the gas flow in the process of introducing the inert gas, so that residual air in the low-temperature pipeline is completely discharged, the content of the inert gas in the low-temperature pipeline in the welding process can be controlled, the welding seam is prevented from being oxidized in the welding process, and the welding quality is effectively ensured.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic view of the structure of the reversing valve.

Fig. 2 is a schematic structural view of the limiting assembly.

Fig. 3 is a schematic view of the stop assembly installed in the first intake valve cavity.

FIG. 4 is a schematic diagram showing the on-off state of each valve cavity in the valve before the valve is used.

FIG. 5 is a schematic illustration of gas flow from the first inlet chamber into the diverter valve within a first set flow range.

FIG. 6 is a schematic view of gas entering the reversing valve from the second inlet chamber at a second set flow range.

Fig. 7 is a schematic view of one of the structures of the seal holder.

Fig. 8 and 9 are schematic diagrams illustrating air discharge from the inside of the pipe in the related art.

Fig. 10 is a schematic view of the structure of the sealing device of the present invention.

FIG. 11 is a cross-sectional view of the sponge body of FIG. 10 taken along the line C-C.

Fig. 12 is a view from a in fig. 10.

Figure 13 is a schematic view of the installation of the sealing device of the invention in a cryogenic pipeline.

FIG. 14 is a schematic view of the application of a pulling force on the sealing device to move it to the next weld.

FIG. 15 is a schematic view of the frictional force experienced by the sponge body during its movement.

FIG. 16 is a schematic view of the elastic deformation of the sponge body during its movement.

FIG. 17 is a schematic view of the structure of the detecting unit of the present invention.

FIG. 18 is a schematic view of the structure of the nozzle.

The reference numerals in the figures have the meaning:

1 is a valve body, 2 is a first air inlet valve cavity, 3 is a second air inlet valve cavity, 4 is an air outlet valve cavity, 5 is a connecting flow channel, 6 is a switch valve group, 7 is a spring, 8 is a valve core, 9 is a limiting component, 10 is a limiting seat, 11 is a threaded seat, 12 is an adjusting rod, 13 is a tubular seat body, 14 is a seat ring, 15 is a sealing seat, 16 is an air inlet pipe, 17 is an air outlet pipe, 18 is a welding line, 19 is inert gas, 20 is air, 21 is a sponge plug,

22 is a low-temperature pipeline, 23 is a sponge body, 24 is a reversing valve, 25 is a sampling port, 26 is a reinforcing support, 27 is a traction rope, 28 is a connecting joint, 29 is a non-pressure bubble, 30 is a sealing insulating material, 31 is a detection joint, 32 is a filter, 33 is a gas flowmeter, 34 is a gas detection device, 35 is a spray pipe, 36 is a main pipeline, 37 is a branch pipeline, and 38 is an expander.

Detailed Description

For better understanding of the technical solutions of the present invention, the following detailed descriptions of the embodiments of the present invention are provided with reference to the accompanying drawings.

It should be understood that the described embodiments are only some embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The present application is described in further detail below with reference to specific embodiments and with reference to the attached drawings.

In the description of the present application, unless explicitly stated or limited otherwise, the terms "first", "second", and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; the term "plurality" means two or more unless specified or indicated otherwise; the terms "connected" and "fixed" are used in a broad sense, for example, "connected" may be a fixed connection, a detachable connection, or an integral connection; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the description of the present application, it should be understood that the terms "upper", "lower", "left", "right", and the like used in the embodiments of the present application are described with reference to the angles shown in the drawings, and should not be construed as limiting the embodiments of the present application. In addition, in this context, it will also be understood that when an element is referred to as being "on" or "under" another element, it can be directly on "or" under "the other element or be indirectly on" or "under" the other element via an intermediate element.

The embodiment I provides a detection device for inert gas filling of a low-temperature pipeline of an LNG ship, which comprises a sealing device and a gas detection module.

The sealing device is used for being installed behind a welding seam of the low-temperature pipeline 22 to seal the pipeline, air in the pipeline can be exhausted by filling inert gas into the end portion of the pipeline, and the phenomenon that the welding quality of the welding seam is affected by residual air in the low-temperature pipeline 22 is avoided.

The sealing device comprises a sponge body 23 and a diverter valve 24.

The sponge body 23 is used for plugging the low-temperature pipeline 22 and is of a circular truncated cone-shaped structure, the end face of the sponge body facing the welding seam 18 is oval, and the end face of the sponge body facing away from the welding seam 18 is circular. The sponge body 23 is provided with two sampling ports 25, and the two sampling ports 26 are vertically and vertically arranged on the end surface of the sponge body 23 facing the welding seam 18. Gas within the cryogenic line 22 may enter the reversing valve 24 through a sampling port 26.

In this embodiment, the diameter D of the end surface of the sponge body 23 on the side away from the weld joint 18 is 1.1D, and D is the inner diameter of the cryogenic pipeline; the long axis of the end face of the sponge body 23 facing the welding seam 18 is 1.1-1.2D, and the long axis is D; the thickness of the sponge body 23 is 1/3-1/4D. The sponge body 23 is made of a material with fatigue performance meeting the GB/T10802-2006 requirement, and preferably, PU polyurethane sponge can be selected.

The reversing valve 24 comprises a valve body 1, a first air inlet valve cavity 2, a second air inlet valve cavity 3, an air outlet valve cavity 4 and a connecting flow channel 5 are arranged inside the valve body, the first air inlet valve cavity 2, the second air inlet valve cavity 3 and the air outlet valve cavity 4 are communicated through the connecting flow channel 5, the first air inlet valve cavity 2 and the second air inlet valve cavity 3 are connected with a sampling port 25 on the sponge body through an air inlet pipe 16, and the air outlet valve cavity 4 is connected with a gas detection module through an air outlet pipe 17.

And switch valve groups 6 are arranged in the first air inlet valve cavity 2, the second air inlet valve cavity 3 and the air outlet valve cavity 4. The switch valve groups 6 in the three valve cavities have the same structure and respectively comprise a spring 7 and a valve core 8 fixedly connected with the spring 7, and the spring in each valve cavity is fixed on a step at the air outlet of the valve cavity.

In this embodiment, the elasticity of the spring in the first air inlet valve cavity 2 is smaller than that of the spring in the second air inlet valve cavity 3, and the elasticity of the spring in the air outlet valve cavity 4 is equal to that of the spring in the first air inlet valve cavity 2.

And a limiting assembly 9 used for keeping the air inlet of the valve cavity in a normally open state is further arranged in the first air inlet valve cavity 2. The limiting assembly 9 not only has the function of keeping the valve cavity air inlet of the first air inlet valve cavity 2 normally open, but also has the function of adjusting the maximum flow which can be borne by the switch valve group in the first air inlet valve cavity 2.

Specifically, the limiting assembly 9 includes a limiting seat 10 fixedly connected to the valve body 1, a threaded seat 11 fixed in the limiting seat 10, and an adjusting rod 12 fixed in the threaded seat 11, and a bottom of the adjusting rod 12 extends out of the threaded seat 11 and abuts against the valve block of the first air inlet valve cavity 2. In this embodiment, the limiting seat 10 is composed of a tubular seat body 13 and a seat ring 14 uniformly arranged in the tubular seat body 13, and the seat ring 14 is arranged along the radial direction of the tubular seat body 13; the adjusting rod 12 is a screw rod with a straight groove at the top.

After the valve of the present invention is used for a long time, the spring in the first intake valve chamber 2 may be fatigued, thereby affecting the accuracy of on-off. For example, when the valve is initially used, the maximum flow threshold value which can be borne by the switch valve group in the first air inlet valve cavity 2 is 10L/min, when the gas flow is less than 10L/min, the first air inlet valve cavity 2 is long-pass, and when the gas flow is more than 10L/min, the first air inlet valve cavity 2 is closed; if the valve is used for a long time, the spring is fatigued, and the phenomenon that the first gas inlet valve cavity 2 is closed in advance when the gas flow rate does not reach 10L/min possibly occurs, so that the discharging effect of residual gas in the low-temperature pipeline is influenced, and at the moment, the maximum flow threshold value born by the switch valve group can be readjusted to 10L/min by screwing the adjusting rod 12.

Preferably, a sealing seat 15 is further arranged between the contact positions of the switch valve group and the valve cavity in the first air inlet valve cavity 2, the second air inlet valve cavity 3 and the air outlet valve cavity 4. In this embodiment, the sealing seat 15 is a sealing ring (as shown in fig. 7) disposed at the inlet and outlet of the valve cavity, or a sealing gasket (as shown in fig. 1) attached and fixed to the inner wall of the valve cavity and matching with the shape of the inner wall of the valve cavity.

Before the reversing valve is used, the first air inlet valve cavity 2 is kept in a normally open state under the action of the limiting assembly 9, and the second air inlet valve cavity 3 and the air outlet valve cavity 4 are kept in a normally closed state, as shown in fig. 4. When the first air inlet valve cavity 2 is kept in a normally open state, the air inlet of the valve cavity is opened. When the second air inlet valve cavity 3 and the air outlet valve cavity 4 are kept in a normally closed state, the valve cores of the second air inlet valve cavity 3 and the air outlet valve cavity 4 are respectively abutted against the valve body at the air inlet of the valve cavity, so that the air inlet of the valve cavity is kept closed.

When the gas flow is within the first set flow range, because the first gas inlet valve cavity 2 is normally open, the gas enters the connecting flow passage 5 along the first gas inlet valve cavity 2 and flows to the valve cavity gas inlet of the gas outlet valve cavity 4 along the connecting flow passage 5, the gas pushes the valve core in the gas outlet valve cavity 4 to move rightwards to compress the spring thereof, the valve cavity gas inlet of the gas outlet valve cavity 4 is opened, so that the gas flows out of the valve body, and the gas flows into the gas detection module through the gas outlet pipe, as shown in fig. 5.

When the gas flow is increased to be within a second set flow range, the switch valve groups in the first gas inlet valve cavity 2 and the second gas inlet valve cavity 3 both move towards the gas outlets of the respective valve cavities under the action of gas pressure, in the process, gas flow pushes the valve core of the second gas inlet valve cavity 3 to move upwards from the gas inlet of the valve cavity to compress the spring of the valve core, the gas inlet of the valve cavity of the second gas inlet valve cavity 3 is opened, and gas flows into the connecting flow channel; meanwhile, at the moment of introducing gas, the first gas inlet valve cavity 2 is opened, so that the gas can enter the first gas inlet valve cavity 2, and the gas flow is overlarge at the moment and is larger than the maximum flow threshold value which can be borne by the switch valve group in the first gas inlet valve cavity 2, so that the gas can press the valve core of the first gas inlet valve cavity 2 to move downwards to compress the spring of the valve core, the valve core is clamped at the gas outlet of the valve cavity, and the gas outlet of the valve cavity of the first gas inlet valve cavity 2 is closed. The gas entering the connecting flow passage 5 flows to the valve cavity gas inlet of the gas outlet valve cavity 4 along the connecting flow passage 5, the gas pushes the valve core in the gas outlet valve cavity 4 to move rightwards to compress the spring of the valve core, the valve cavity gas inlet of the gas outlet valve cavity 4 is opened, so that the gas flows out of the valve body, and the gas flows into the gas detection module through the gas outlet pipe, as shown in fig. 6.

The gas detection module is used for detecting the oxygen content in the gas discharged from the reversing valve 24 so as to judge whether all residual gas in the low-temperature pipeline 22 is discharged.

The gas detection module comprises a detection joint 31, a filter 32, a gas flowmeter 33, a gas detection device 34 and a spray pipe 35 which are sequentially arranged along a flow path of gas, wherein the detection joint 31, the filter 32, the gas flowmeter 33, the gas detection device 34 and the spray pipe 35 are connected through a gas pipe, and the gas pipe is provided with a ball valve. The sensing connection 31 is connected to the diverter valve 24.

In this embodiment, the filter 32 is an atomizing filter for atomizing the gas to be detected to ensure uniform gas concentration, so as to facilitate the subsequent detection of the gas flowmeter and the gas detection device.

The gas flow meter 33 is preferably a flow meter with a range of 0 to 30L/min, and is used for detecting the gas flow in the upper and lower sampling ports of the sponge main body 23.

The gas detection device 34 has two detection modes of inert gas and oxygen gas, ensuring that changes in the contents of both gases can be detected.

The nozzle 35 is composed of a main pipeline 36, a branch pipeline 37 and an expander 38, the main pipeline 36 is connected with an air outlet of the gas detection device 34, the branch pipeline 37 is obliquely fixed on the main pipeline 36, an included angle between the branch pipeline 37 and the main pipeline 36 is 60 degrees, and compressed air can be introduced into the branch pipeline 37. The expander 38 ensures that the gas containing the IG inert gas can diffuse rapidly into the atmosphere.

The invention discloses a method for detecting inert gas filling of a low-temperature pipeline of an LNG ship, which comprises the following steps:

step 1, assembling the detection device for filling inert gas into the low-temperature pipeline of the LNG ship, provided by the invention: the sponge body 23, the reversing valve 24 and the traction reinforcing component are assembled into a whole, namely, the reinforcing support 26 is embedded in the sponge body 23, the air inlet pipe 16 is respectively connected with the reversing valve 24 and the sampling port 25 of the sponge body 23, the reversing valve 24 is arranged in the center of the end face of the sponge body 23 facing one side of the welding line 18, and the reversing valve 24 and the air inlet pipe 16 are bound and fixed with the sponge body 23 into a whole through adhesive tapes. The outlet line on the diverter valve 24 is then connected to the test connection on the gas test module.

Compressed air with the flow rates of 5-10L/min, 15-10L/min and 0L/min is respectively introduced into the reversing valve, and the reversing valve is debugged to ensure that each valve cavity can be normally opened and closed within a corresponding flow range.

Step 2, the staff gets into low temperature pipeline 22, through extrusion sponge body 23 both sides, presets the sealing device of this application in pipeline a certain welding seam rear (as shown in fig. 13) to ensure that upper and lower two sample connection 25 arrange along the vertical direction, observe whether sponge body 23 and pipeline inner wall laminating are sealed, whether the levelness of sample connection 25 satisfies the requirement through non-pressure bubble 29 inspection simultaneously.

And 3, filling inert gas into the pipeline from the gas inlet of the low-temperature pipeline 22, and when the oxygen meter detects that the oxygen concentration in the gas discharged from the groove of the welding seam 18 is not more than 2%, covering the groove of the welding seam 18 by using an adhesive tape for sealing.

And 4, filling 15-20L/min inert gas into the low-temperature pipeline 22 from the gas inlet of the low-temperature pipeline, opening the gas inlet of the valve cavity of the second gas inlet valve cavity 3, closing the gas outlet of the valve cavity of the first gas inlet valve cavity 2, making the gas flow out of the valve body from the second gas inlet valve cavity 3, the connecting flow channel 5 and the gas outlet valve cavity 4, and flowing into the gas detection module through the gas outlet pipe, so that residual air in the pipeline is discharged, and the content of discharged gas is detected through the gas detection device, so that most of the residual air is ensured to be discharged. The inflation time can be reduced by filling the inert gas with the flow rate of 15-20L/min into the pipeline, and the inflation efficiency is improved.

In step 5, although most of the residual air is discharged, a small amount of residual air accumulates above the interior of the pipeline due to the light specific gravity of the air. Therefore, after the inert gas with the flow rate of 15-20L/min is introduced for a period of time, the flow rate of the inert gas can be adjusted to 5-10L/min, at the moment, because the flow rate is reduced, under the elastic action of the spring, the valve core of the second gas inlet valve cavity 3 moves downwards to close the gas inlet of the valve cavity, the valve core of the second gas inlet valve cavity 3 moves upwards to open the gas outlet of the valve cavity, and the gas flows out of the valve body from the first gas inlet valve cavity 2, the connecting flow passage 5 and the gas outlet valve cavity 4 and flows into the gas detection module through the gas outlet pipe 17, so that residual air accumulated above the pipeline is discharged. When the gas detection device detects that the oxygen content in the discharged gas is zero, the residual air is completely discharged out of the pipeline, and the welding seam of the pipeline has welding conditions, so that the welding work can be started.

In the process of welding the pipeline, in order to ensure that the content of the inert gas in the pipeline is always maintained at the standard concentration, the first gas inlet valve cavity 2 can be kept normally open, namely the filling flow of the inert gas is maintained at 5-10L/min.

In the second embodiment, the detection apparatus for detecting inert gas filled in a cryogenic pipeline of an LNG ship provided in this embodiment is substantially the same as that in the first embodiment, specifically, a traction reinforcing assembly is further disposed on the sealing apparatus, and the traction reinforcing assembly includes a reinforcing bracket 26, a traction rope 27 and a connection joint 28.

The reinforcing bracket 26 is embedded in the sponge body 23, two ends of the reinforcing bracket extend out from the side surface of the sponge body 23 and are respectively fixed with one traction rope 27, and the two traction ropes 27 are fixed on the connecting joint 28 in an intersecting manner.

In this embodiment, the reinforcing bracket 26 is a U-shaped plate, the length of the bent side is not less than 2/3 of the thickness of the sponge body 23, and the width of the reinforcing bracket 26 is 1/3 of the thickness of the sponge body 23. Strengthen support 26 and inlay in sponge body 23 and its limit of buckling stretches out from the terminal surface that deviates from welding seam 18 one side of sponge body 23, still mountable non-pressure bubble 29 on the extension, non-pressure bubble 29 is used for measuring the levelness of sample connection 25 after sponge body 23 installation is accomplished.

The reinforcing brace 26 is fixed to the center position inside the sponge body 23 in the vertical line direction. The end of the part of the reinforcing bracket 26 extending from the sponge body 23 is fixed with a pulling rope 27, the upper pulling rope 27 and the lower pulling rope 27 are fixed on a connecting joint 28 in a crossing way, and the length of the pulling rope 27 is at least 2 times of the inner diameter of the cryogenic pipeline 22. When in use, the upper and lower pulling ropes 27 and the reinforcing bracket 26 form a triangular reinforcing protection structure, and the pulling reinforcing component can also be used as a pulling head of the sponge body 23.

Preferably, the sponge body 23 is further covered with a layer of sealing and insulating material 30 to perform sealing, insulating and protecting functions, and meanwhile, the phenomenon that the sponge body is worn, heated, wetted or soaked in water during use is avoided.

The method for detecting the filling of inert gas into the low-temperature pipeline of the LNG ship in the embodiment comprises the following steps:

step 1, assembling the detection device for filling inert gas into the low-temperature pipeline of the LNG ship, provided by the invention: the sponge body 23, the reversing valve 24 and the traction reinforcing component are assembled into a whole, namely, the reinforcing support 26 is embedded in the sponge body 23, the air inlet pipe 16 is respectively connected with the reversing valve 24 and the sampling port 25 of the sponge body 23, the reversing valve 24 is arranged in the center of the end face of the sponge body 23 facing one side of the welding line 18, and the reversing valve 24 and the air inlet pipe 16 are bound and fixed with the sponge body 23 into a whole through adhesive tapes. The outlet line on the diverter valve 24 is then connected to the test connection on the gas test module.

Compressed air with the flow rates of 5-10L/min, 15-10L/min and 0L/min is respectively introduced into the reversing valve, and the reversing valve is debugged to ensure that each valve cavity can be normally opened and closed within a corresponding flow range.

Step 2, the staff gets into low temperature pipeline 22, through extrusion sponge body 23 both sides, presets the sealing device of this application in pipeline a certain welding seam rear (as shown in fig. 13) to ensure that upper and lower two sample connection 25 arrange along the vertical direction, observe whether sponge body 23 and pipeline inner wall laminating are sealed, whether the levelness of sample connection 25 satisfies the requirement through non-pressure bubble 29 inspection simultaneously.

And 3, filling inert gas into the pipeline from the gas inlet of the low-temperature pipeline 22, and when the oxygen meter detects that the oxygen concentration in the gas discharged from the groove of the welding seam 18 is not more than 2%, covering the groove of the welding seam 18 by using an adhesive tape for sealing.

And 4, filling 15-20L/min inert gas into the low-temperature pipeline 22 from the gas inlet of the low-temperature pipeline, opening the gas inlet of the valve cavity of the second gas inlet valve cavity 3, closing the gas outlet of the valve cavity of the first gas inlet valve cavity 2, making the gas flow out of the valve body from the second gas inlet valve cavity 3, the connecting flow channel 5 and the gas outlet valve cavity 4, and flowing into the gas detection module through the gas outlet pipe, so that residual air in the pipeline is discharged, and the content of discharged gas is detected through the gas detection device, so that most of the residual air is ensured to be discharged. The inflation time can be reduced by filling the inert gas with the flow rate of 15-20L/min into the pipeline, and the inflation efficiency is improved.

In step 5, although most of the residual air is discharged, a small amount of residual air accumulates above the interior of the pipeline due to the light specific gravity of the air. Therefore, after the inert gas with the flow rate of 15-20L/min is introduced for a period of time, the flow rate of the inert gas can be adjusted to 5-10L/min, at the moment, because the flow rate is reduced, under the elastic action of the spring, the valve core of the second gas inlet valve cavity 3 moves downwards to close the gas inlet of the valve cavity, the valve core of the second gas inlet valve cavity 3 moves upwards to open the gas outlet of the valve cavity, and the gas flows out of the valve body from the first gas inlet valve cavity 2, the connecting flow passage 5 and the gas outlet valve cavity 4 and flows into the gas detection module through the gas outlet pipe 17, so that residual air accumulated above the pipeline is discharged. When the gas detection device detects that the oxygen content in the discharged gas is zero, the residual air is completely discharged out of the pipeline, and the welding seam of the pipeline has welding conditions, so that the welding work can be started.

In the process of welding the pipeline, in order to ensure that the content of the inert gas in the pipeline is always maintained at the standard concentration, the first gas inlet valve cavity 2 can be kept normally open, namely the filling flow of the inert gas is maintained at 5-10L/min.

Step 6, after the welding of the welding seam is completed, the connecting joint 28 is pulled, the sponge body 23 can be driven to move to the next welding seam through a triangular reinforced protection structure formed by the connecting joint 28, the traction rope 27 and the reinforced support 26, at the moment, the pulling force applied to the upper bending part and the lower bending part of the reinforced support 26 is the same as that applied to the upper bending part and the lower bending part of the reinforced support 26 (as shown in fig. 14, the upper bending part and the lower bending part of the reinforced support are the same as that applied to the lower bending part of the upper bending part and the lower bending part of the reinforced support 26, the friction force between the top part and the bottom part of the sponge body 23 and the pipe wall is the same, and the sponge body 23 cannot turn over along the central line of the pipeline in the moving process.

Meanwhile, because the friction force of the two sides of the end face (the elliptical end face) of the sponge body 23 facing the weld joint 18 is smaller than the friction force of the top and the bottom of the end face (the elliptical end face) (as shown in fig. 15), in the moving process, the positions, attached to the pipe wall, of the two sides of the long axis of the end face (the elliptical end face) of the sponge body 23 facing the weld joint are deformed completely (elastically deformed) with a certain radian under the action of tensile force, and the situation that the sponge body 23 is overturned along the left and right directions of the pipeline (as shown in fig. 16) cannot occur in the moving process.

After the sealing device is moved to the corresponding position, the traction pulling force is released, the elastic deformation of the sponge body 23 is recovered, and the sponge body is attached to the pipe wall again to achieve a sealing state.

And then, repeatedly executing the steps until all the welding seams are welded.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.