1. Overview

Stainless steel pipe finishes vary depending on the environment. Understanding the impact of the environment on stainless steel pipes helps us choose the type of stainless steel pipes correctly, otherwise stainless steel pipes will also rust and corrode. Different stainless steel pipes require different surface treatments, such as:

•Acid-washed or sandblasted finishes for stainless steel seamless pipes (industrial);

•Polished surface of stainless steel sanitary pipes (seamless);

•Polished surface of small diameter stainless steel welded pipe;

•Pickling surface treatment or sandblasting treatment of stainless steel welded pipes (industrial use);

•Internal and external polishing (welding) of stainless steel sanitary pipes.


2. Preprocessing

Pretreatments such as pickling, chemical brightening, electrochemical polishing, electroplating, passivation, black coating, color coating, chemical processing, etc. are important steps in the surface treatment of stainless steel pipes. Before the stainless steel pipe is formed, there may be oil, burrs, uneven surfaces, and oxides on the surface. Therefore, these defects should be removed before surface treatment.

The dirt that needs to be removed from the surface of stainless steel pipes can be divided into organic matter and inorganic matter. Organics include mineral oils such as diesel, motor oil, petroleum jelly, paraffin, animal oils and vegetable oils such as soybean oil, tea oil, rapeseed oil, lard and tallow. Oil contamination is mainly lubricating oil, cutting oil, quenching oil, polishing oil or fingerprints produced during the processing of stainless steel pipes. Inorganic matter includes soil, dust, compounds, etc. generated during heat treatment.


3. Stainless steel pipe pretreatment program

(1) Polishing: remove the surface roughness of stainless steel and mechanically grind and polish it to a certain surface finish;

(2) Degreasing: remove surface oil;

(3) Pickling: remove surface oxides;

(4) Weak corrosion: activate the surface to be treated, remove the surface passivation film, and expose the metal crystal structure.


4. Surface treatment methods of stainless steel pipes:

(1) Mechanical method: Use a polishing machine or other machine to remove surface roughness.

(2) Chemical method: use alkaline solution to remove oil, use acidic solution to pickle, use organic solvent to dissolve grease and remove scale.

(3) Electrochemical process: Use electrochemistry to remove oil and perform electrochemical etching.

(4) Rolling polish, centrifugal rolling polish, centrifugal disk polishing, rotating polishing, suitable for small parts with flattening and rust removal effects.

(5) Sandblasting treatment: suitable for large-area treatment, with the effect of decontamination and oxide scale removal.

Therefore, the appropriate method should be selected based on the surface condition of the stainless steel pipe and subsequent quality requirements.