A construction process for high-pressure clean thick-walled pipeline

Abstract

The invention discloses a construction process for a high-pressure clean thick-walled pipeline, and relates to the technical field of high-pressure clean thick-walled pipelines. A seamless steel pipe is selected to meet the high-pressure requirement. The seamless steel pipe is subjected to mechanical polishing, pickling, passivation or electrolytic polishing (EP) to improve the corrosion resistance of the inner wall. The pipeline is connected by full argon arc welding, 999.99% high-purity argon gas, and welding is performed layer by layer. The interlayer temperature is controlled to be less than 100 degrees, and oxidation is controlled. The construction process for the high-pressure clean thick-walled pipeline effectively improves the cleanliness of the pipeline, meets the cleanliness quality of the high-pressure pipeline, and enables the internal roughness of the pipeline to reach within ra=0.5um, with a mirror effect, thereby improving cleanliness and ensuring high product quality. By adopting a robot arm for automatic welding, the machine replaces manual labor, improves efficiency, improves prefabrication efficiency, improves pipeline construction quality, reduces the frequency of dangerous high-altitude welding operations, and reduces the cost increase of rework due to the influence of welding quality.

Description

Technical Field

[0001] The invention relates to the technical field of high-pressure clean pipelines, and in particular to a construction process for high-pressure clean thick-wall pipelines. Background Art

[0002] With the need for high-quality development in the country, the purity and cleanliness requirements of new materials are getting higher and higher, especially for electronic-grade chemicals, ultra-clean polymers, etc. Their production equipment and pipelines must be resistant to high pressure and corrosion, and polished and clean, with a clean polishing degree of less than 0.5um. There is no cleanliness requirement in the traditional design process. The conventional pipe making process is the ordinary perforation process, which does not require the cleanliness of the pipeline, and manual arc welding is used on site. To this end, we propose a construction process for high-pressure clean thick-walled pipelines. Summary of the invention

[0003] The purpose of the present invention is to provide a construction process for a high-pressure clean thick-walled pipeline to solve the problems raised in the above background technology.

[0004] To achieve the above object, the present invention provides the following technical solution: a construction process for a high-pressure clean thick-walled pipeline, the process flow of which includes the following steps:

[0005] S1: Choose seamless steel pipe to meet the high pressure requirements;

[0006] S2: Improve the corrosion resistance of the inner wall of seamless steel pipes by mechanical polishing, pickling, passivation or electrolytic polishing (EP);

[0007] S3: Pipeline connection adopts full argon arc welding, 999.99% high-purity argon gas, welding layer by layer, controlling the interlayer temperature to less than 100 degrees, and controlling no oxidation;

[0008] S4: Use arm robot welding machine to control the internal convex height of the weld, improve cleanliness and production efficiency, such as the outer diameter of a 4-inch high-pressure pipeline is 114.3mm, the wall thickness is sch160 up to 14.4mm, multi-layer welding, suitable for machine automatic welding;

[0009] S5: The final stage uses weak acid cleaning to improve cleanliness.

[0010] Preferably, the seamless steel pipe in step S1 is made according to ASME B36.19 or HG205531a steel pipe specification, using high-quality parent material and hot extrusion seamless pipe process, wherein the round bar parent material is made of controlled sulfur and phosphorus content (the control value of sulfur (S) is generally required to be ≤0.030%, and the control value of phosphorus (P) is generally required to be ≤0.045%).

[0011] Preferably, in step S3, sufficient 5 9 high-purity argon gas is required to control the oxidation color of the inner weld during the full argon arc welding process.

[0012] Preferably, the weak acid used for cleaning in step S5 is citric acid, and citric acid is used for overall cleaning and passivation.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: the construction process of the high-pressure clean thick-walled pipeline effectively improves the cleanliness of the pipeline, meets the cleanliness quality of the high-pressure pipeline, and enables the internal roughness of the pipeline to reach within ra=0.5um, with a mirror effect, improves cleanliness, and ensures high product quality. By adopting automatic welding with a robot arm, the machine replaces manual labor, improves efficiency, improves prefabrication efficiency, improves pipeline construction quality, and reduces the frequency of dangerous high-altitude welding operations; reduces the cost increase of rework due to the impact of welding quality. DETAILED DESCRIPTION

[0014] The following will combine the contents in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] A construction process for high-pressure clean thick-walled pipes, mainly used for high-pressure (up to 25Mpa) and clean (ra less than 0.5um) large-diameter (greater than or equal to 1 inch) pipes in material pipeline projects for high-pressure polymerization reactions (large-diameter pipes are larger than 1 inch in this production line), with a wall thickness of sch160 up to 14.4mm. The process requirements are the first in China, and there is no construction experience to follow. The process flow includes the following steps:

[0016] S1: Choose seamless steel pipes to meet the requirements of high pressure. Seamless steel pipes are made by hot extrusion process. The density and inner surface quality are higher than those of ordinary perforated pipes, which can ensure the cleanliness of the next polishing process. In addition, the selection of pipe fittings needs to be selected from the same manufacturer as the pipes, so that the tolerance matching degree of pipe fittings and pipes is high;

[0017] S2: Improve the corrosion resistance of the inner wall of seamless steel pipes by mechanical polishing, pickling, passivation or electrolytic polishing (EP);

[0018] S3: Pipeline connection adopts full argon arc welding, 999.99% high-purity argon gas, welding layer by layer, controlling the interlayer temperature to less than 100 degrees, controlling no oxidation, and the oxidation color control of the inner weld during full argon arc welding requires sufficient 5 9 high-purity argon gas;

[0019] S4: Use arm robot welding machine to control the internal convex height of the weld, improve cleanliness and production efficiency. For example, the outer diameter of a 4-inch high-pressure pipeline is 114.3mm, the wall thickness is sch160 up to 14.4mm, and multi-layer welding is suitable for machine automatic welding, which improves cleanliness and production efficiency.

[0020] S5: In the final stage, weak acid cleaning is used to improve cleanliness. The weak acid used is citric acid, and citric acid is used for overall cleaning and passivation.

[0021] Preferably, the seamless steel pipe in step S1 is made according to ASME B36.19 or HG205531a steel pipe specification, using high-quality parent material and hot extrusion seamless pipe process, wherein the round bar parent material is made of controlled sulfur and phosphorus content (the control value of sulfur (S) is generally required to be ≤0.030%, and the control value of phosphorus (P) is generally required to be ≤0.045%).

[0022] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A construction process for a high-pressure clean thick-walled pipeline, characterized in that: The process includes the following steps: S1: Choose seamless steel pipe to meet the high pressure requirements; S2: Improve the corrosion resistance of the inner wall of seamless steel pipes by mechanical polishing, pickling, passivation or electrolytic polishing (EP); S3: Pipeline connection adopts full argon arc welding, 999.99% high-purity argon gas, welding layer by layer, controlling the interlayer temperature to less than 100 degrees, and controlling no oxidation; S4: Use arm robot welding machine to control the internal convex height of the weld, improve cleanliness and production efficiency, such as the outer diameter of a 4-inch high-pressure pipeline is 114.3mm, the wall thickness is sch160 up to 14.4mm, multi-layer welding, suitable for machine automatic welding; S5: The final stage uses weak acid cleaning to improve cleanliness.

2. The construction process of a high-pressure clean thick-walled pipeline according to claim 1 is characterized in that: The seamless steel pipe in step S1 is made according to ASME B36.19 or HG205531a steel pipe specification, using high-quality parent material and hot extrusion seamless pipe process, wherein the round bar parent material is made of controlled sulfur and phosphorus content (the control value of sulfur (S) is generally required to be ≤0.030%, and the control value of phosphorus (P) is generally required to be ≤0.045%).

3. The construction process of a high-pressure clean thick-walled pipeline according to claim 1 is characterized in that: In the step S3, the oxidation color control of the inner weld during the full argon arc welding process requires sufficient 5 9 high-purity argon gas.

4. The construction process of a high-pressure clean thick-walled pipeline according to claim 1 is characterized in that: The weak acid cleaning used in the step S5 is citric acid, and citric acid is used for overall cleaning and passivation.