Argon filling device for local welding in stainless steel pipe

Abstract

The utility model relates to a kind of argon filling devices for local welding in stainless steel pipeline, several gas flow pipes are communicated with annular air pipe by welding mode and are connected by welding mode;Two ends are equipped with circular rubber sealing plate, rubber sealing plate is clamped by two pieces of baffle made of thin steel plate, baffle is connected with rubber sealing plate by bolt and is clamped and fixed;Air inlet duct of air inlet end is led through two pieces of steel plate and rubber sealing plate and is communicated with annular air pipe and is welded connection, annular air pipe is welded and fixed on inner baffle;Outer baffle on the end far from air inlet duct is equipped with handle.It is applicable to pipeline diameter 450mm below pipeline, installation is convenient;Argon supply is uniform and stable, and sealing effect is good, to ensure good argon protection atmosphere;Production cost is low, easy to take out after welding.

Description

Technical Field

[0001] This invention belongs to the field of welding technology and relates to a local argon filling device for filling the pipe with protective gas during the welding process of stainless steel pipes. Background Technology

[0002] Crude benzene is one of the products of crude coal gas generated from coal pyrolysis. It is a benzene-series compound recovered from coke oven gas after ammonia removal, with benzene being the predominant component, hence the name crude benzene. Crude benzene is a pale yellow, transparent liquid, lighter than water and insoluble in water. It is mainly used in further processing to produce benzene, toluene, xylene, and other products. Benzene, toluene, and xylene are all valuable basic organic chemical raw materials. Crude benzene is highly corrosive and flammable and explosive, readily igniting and exploding upon exposure to high heat or open flame. When transporting corrosive media such as crude benzene through pipelines, the pipeline material must be corrosion-resistant stainless steel, and welding is the best method of connection between pipeline steel sections. Welding technology, as a method of achieving intermetallic connection, can achieve interatomic bonding, forming a dense, permanent joint with performance comparable to or even superior to the base material. This ensures that the pipeline steel can withstand harsh environments, resist corrosion, and prevent leakage during the transportation of corrosive media.

[0003] Stainless steel pipeline welding utilizes butt joints. To ensure full penetration across the entire thickness of the pipe, multi-layer, multi-pass welding is typically employed. This type of butt weld consists of a root pass, a filler pass, and a cap pass. The root pass, located at the root of the weld, is the side in contact with oil and gas media and is the most crucial component. Due to limited welding space, the accessibility of the root pass is poor for small- and medium-diameter pipeline steel, making double-sided welding unsuitable for guaranteeing its quality. Therefore, single-sided welding with double-sided forming technology is employed. Single-sided welding with double-sided forming refers to welding only on one side of the workpiece, achieving a uniform, neat, well-formed weld that meets quality requirements on both the front and back sides. Currently, single-sided welding with double-sided forming technology is the primary method used for welding stainless steel pipeline steel.

[0004] When welding stainless steel pipeline steel, tungsten inert gas (TIG) welding is an ideal method for the root pass. TIG welding has a small welding specification and low heat input, making it easy to control the molten pool during the root pass and reducing the risk of burn-through. Argon is an inert gas that neither dissolves in the molten pool nor reacts chemically with it, effectively protecting the welding area from contamination. Furthermore, with argon as the gas medium, the TIG welding arc is very stable once formed, allowing the welder to easily observe and control the molten pool, ensuring the quality of the weld joint.

[0005] Stainless steel pipeline welding employs tungsten inert gas (TIG) welding for the root pass, effectively ensuring the quality of the weld on the front side. However, during the welding process, the weld on the back side of the stainless steel pipeline is highly susceptible to oxidation, resulting in the loss of alloying elements and the formation of welding defects such as oxide slag and porosity, leading to a decrease in the mechanical properties and corrosion resistance of the weld metal. To ensure the welding quality of the back side, effective protective measures must be taken. When stainless steel pipes are used to transport corrosive media, the pipe specifications are typically 219mm × 8mm. Due to space constraints, construction personnel cannot enter the pipe; therefore, the pipe is generally filled with inert gases such as argon to protect the back side of the weld from oxidation.

[0006] The common methods and characteristics of argon purging for small and medium diameter steel pipelines are as follows:

[0007] (1) Through-type gas filling method: Seal both ends of the pipe with tape, rubber sheet, cardboard, etc., fill the pipe with argon gas from one end, seal the other end, and make a 3-5mm vent hole on the upper part of the sealing plate. During welding, to prevent the argon gas from leaking out too quickly, seal a section of the pipe opening with tape at the weld joint gap, leaving only a pre-welded length of no more than 150mm for continuous welding by the welder. After welding a section, tear off the same length of tape and continue welding until the welding is completed. This method is simple, but it wastes a lot of gas, has high welding costs, and low welding efficiency.

[0008] (2) Soluble paper method: Before assembly, water-soluble paper is attached to the inside of the pipe 150mm away from both sides of the weld joint to form a temporary plug. Then, argon gas is injected into the pipe through the joint gap using an argon-filling needle. After welding, when the pipeline system is subjected to a water pressure test, the water-soluble paper quickly dissolves in the water and is discharged with the water. This method is a local argon filling method, which solves the problems of gas waste and poor protection when welding stainless steel pipes with long pipelines and small diameters using the through-type argon filling method. However, it is troublesome to operate and the sealing effect is not ideal. Summary of the Invention

[0009] The purpose of this invention is to provide a device for local argon filling inside small and medium diameter stainless steel pipelines that is simple in structure, easy to use, and has good argon filling performance.

[0010] The technical solution of the present invention:

[0011] An argon-filling device for localized welding inside stainless steel pipes connects several branch pipes to an annular vent pipe by welding. The branch pipes are densely covered with small branch holes. Both ends are equipped with circular rubber sealing plates, which are held by two baffles made of thin steel plates. The baffles and rubber sealing plates are fastened and fixed with bolts. The air inlet duct passes through the two baffles and the rubber sealing plates and is connected to the annular vent pipe by welding. The annular vent pipe is welded and fixed to the inner baffle.

[0012] Furthermore, a handle is provided on the outer baffle at the end away from the air intake duct.

[0013] The beneficial effects of this invention are: easy installation, good sealing effect, uniform and stable argon gas supply, ensuring a good argon gas protective atmosphere, reducing welding costs, and ensuring welding quality; low manufacturing cost, and the ability to form a series of products according to different pipe diameters; easy to remove after welding; suitable for pipes with a diameter of less than 450mm. Attached Figure Description

[0014] Figure 1 This is a three-dimensional diagram of an argon-filling device used for partial welding inside a stainless steel pipe.

[0015] In the diagram: 1-Intake duct, 2-Baffle, 3-Rubber sealing plate, 4-Bolt, 5-Annular vent pipe, 6-Handle, 7-Airflow pipe, 8-Small hole. Detailed Implementation

[0016] The following explanation is illustrated with reference to the accompanying drawings and examples.

[0017] Figure 1 As shown: An argon-filling device for localized welding inside stainless steel pipes. Several gas flow pipes 7 are connected to an annular vent pipe 5 by welding. The branch pipe is densely covered with branching holes 8. Circular rubber sealing plates 3 are provided at both ends. The rubber sealing plates 3 are held by two baffles 2 made of thin steel plates. The baffles 2 and the rubber sealing plates are connected and clamped together by bolts 4. The gas inlet duct 1 passes through the two baffles 2 and the rubber sealing plates 3 and is connected to the annular vent pipe 5 by welding. The annular vent pipe 5 is welded and fixed to the inner baffle 2. A handle 6 is provided on the outer baffle 2 at the end away from the gas inlet duct 1. The handle 6 is welded to the outer side of the thin steel baffle 2 of the argon-filling device for easy gripping during use. When finished, the device can be pulled out of the pipe by the handle and the pull rope.

[0018] Working process and principle: The device of this invention can be made in various sizes and specifications. The size should match the stainless steel pipeline to be welded, meaning the diameter of the rubber sealing plate of the argon filling device is the same as the inner diameter of the pipeline. In use, the argon filling device is placed inside the stainless steel pipeline to be welded. Inert gas enters the annular vent pipe 5 through the inlet pipe 2, and then is distributed through the annular vent pipe 5 to the gas flow pipe 7, where it is evenly output into the pipeline through the small holes 8. This effectively protects the back of the weld seam, resulting in good welding quality. After welding, the argon filling device is pulled out of the pipeline using a rope and handle 6.

Claims

1. An argon-filling device for localized welding inside stainless steel pipes, characterized in that: Several diversion pipes are connected to the annular vent pipe by welding, and the diversion pipes are densely covered with diversion holes; both ends are equipped with circular rubber sealing plates, which are held by two baffles made of thin steel plates. The baffles and rubber sealing plates are connected and clamped together with bolts; the air intake duct at the air intake end passes through the two connecting plates and the rubber sealing plates and is connected to the annular vent pipe by welding. The annular vent pipe is welded and fixed to the inner baffle.

2. The argon-filling device for partial welding inside stainless steel pipes according to claim 1, characterized in that: A handle is provided on the outer baffle at the end away from the air intake duct.

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