Rust removal methods of thick-walled seamless steel pipes

In the manufacturing and maintenance of thick-walled seamless steel pipes, effective rust removal is crucial to ensure product durability, performance, and longevity. Various methods are employed to clean and prepare the surface of these pipes, each offering distinct advantages depending on the condition of the pipe and the level of rust present. Below are several key methods commonly used to remove rust from thick-walled seamless steel pipes.

Spray Rust Removal

This method involves using a high-power motor to drive jet blades that rotate at high speeds, propelling abrasives such as steel sand, steel shot, wire segments, and minerals onto the pipe surface through centrifugal force. This process effectively removes rust, oxides, and other contaminants while also imparting a uniform roughness to the surface due to the high-impact abrasive action.

Tool-Based Rust Removal

In this method, wire brushes and similar tools are used to manually or mechanically polish the steel surface. This approach is effective for removing loose or raised rust, oxide scale, and welding slag. Cold-drawn seamless steel pipes can be cleaned to Sa2 standard using hand tools, and Sa3 standard with power tools. However, tool-based methods may be less effective when dealing with firmly adhered iron oxide scale, and achieving the necessary surface roughness for subsequent coatings may be difficult.

Cleaning with Solvents

Solvents and emulsions are used to remove oils, grease, dust, and lubricants from the steel surface. While this method cleans surface contaminants, it does not remove rust, scale, or welding flux, making it an auxiliary process rather than a primary rust removal method.

Pickling

Pickling typically involves chemical or electrolytic processes to eliminate rust, scale, and old coatings. Chemical pickling is particularly effective for cleaning pipes before further treatments like sandblasting. While it provides a clean and slightly rough surface, the anchor pattern achieved is often shallow, and chemical pickling can have environmental downsides due to potential pollution.