Carbon steel pipe cleaning method

Abstract

The invention relates to a cleaning method of a carbon steel pipeline with a large diameter. The method comprises the following steps: first, a carbon steel pipeline to be cleaned is placed horizontally, with slight inclination, a container used to collect cleaning residual liquids is arranged under the lower opening of the carbon steel pipeline, and the dust on the inner wall of the carbon steel pipeline is cleaned up; second, the inner wall of the carbon steel pipeline is subjected to degreasing treatment; third, the inner wall of the carbon steel pipeline is cleaned with an acid solution; fourth, the inner wall of the carbon steel pipeline is sprayed and cleaned with a rinsing solution, the rinsing solution is sodium phosphate aqueous solution which is adjusted by phosphoric acid to a pH value of 8-12.5 and the mass fraction of sodium phosphate is 1%-2%; fifth, the inner wall of the carbon steel pipeline is subjected to passivating treatment; sixth, the inner wall of the carbon steel pipeline is subjected to drying treatment; seventh, two ends of the carbon steel pipeline are sealed for protection. The cleaning method has advantages of simple operations, energy saving, environmental protection, low construction cost and good cleaning effects. The invention also relates to carbon steel pipeline cleaning agents used in the above cleaning method.

Description

technical field [0001] The invention relates to a cleaning method for large-diameter carbon steel pipelines, and also relates to a cleaning agent for carbon steel pipelines used in the cleaning method. Background technique [0002] In the field of engineering construction, especially the air separation plant project that requires high cleanliness of the process pipeline, the surface of the carbon steel pipeline in contact with the medium needs to be chemically cleaned to remove foreign matter such as grease, rust, and oxide layers on the steel surface. Ensure the cleanliness of the inner wall of the pipeline. [0003] Typical industrial pipe cleaning processes include: [0004] 1. The degreasing process removes the grease on the surface of the steel; [0005] 2. The pickling process, to remove the rust on the steel surface, is a process of chemical rust removal; [0006] 3. Neutralization process, neutralize the residual pickling solution; [0007] 4. Passivation process...

AI Technical Summary

Problems solved by technology

In view of the increasing scale of the current industrial production equipment, the corresponding pipeline diameter is also increasing (for example, 2 meters in diameter or more), so the cleaning tank must also be made very large (the usual length of the pipe section is 12 meters, so The specification of the cleaning tank needs to be at least 2.5m x 2.5m x 12.5m, and its volume is nearly 80m 3 ), the amount of chemicals in full bloom is also very considerable, which has a great impact on the construction cost and the environment. At the same time, the pipe section adopts the tank immersion method to construct a fixed work site, and the pipe section to be cleaned needs to be between the installation site and the cleaning site. Back-and-forth transportation, resulting in a large amount of hoisting and transportation machinery shift costs

[0012] Regardless of whether the circulation method or the tank immersion method is adopted, the principle is to use the chemical agent to interact with the foreign matter attached to the surface to be cleaned, and dissolve or convert the foreign matter into soluble components through the process of dissolution or chemical reaction, so that it can be removed from the surface to be cleaned. The surface falls off and is taken out of the pipe section with the flow of chemicals, but because only the inner surface of the pipe section needs to be cleaned, and in order to ensure that all surfaces are cleaned, the interior of the pipe section has to be filled with chemicals, and a large number of Only the part of the chemical agent that is in direct contact with the pipe wall (accounting for a very small part of the total amount) is reacting or dissolving with the foreign matter, and the chemical agent far away from the pipe wall does not participate in the chemical reaction or dissolution, causing a lot of waste , and the tank immersion method cleans the outer surface that does not need to be cleaned at the same time as the inner surface of the pipe section, and the waste of drugs is greater

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