Precision Mechanical Polishing Services for Metal Finishing

Mechanical polishing creates a smooth, uniform, and bright finish on tubing by using progressively finer abrasives. For ornamental purposes, finishes range from mill finish and bright finish to 180, 240, or 400 grit polish, with finer options available upon request. For sanitary tubing, both the inside and outside are polished to create a smooth surface that helps prevent biological buildup. Mechanical polishing can also prepare tubing for electropolishing to achieve the desired final finish.

What is mechanical polishing?

Removes surface irregularities and imperfections (weld slag, paint, loose scale, and dirt)
Improves metal durability and longevity
Enhances smoothness for a high-quality finish

What can be mechanically polished?

Components, Parts & Systems that can be polished include:

Tube, Pipe, Spools, Manifolds, and Fittings
Heat Exchangers
Valves
Fabricated Specials
Copper, Carbon, and Stainless Steel

What is passivation?

Passivation polishing is the treatment of the stainless steel with an oxidizing chemical (typically nitric or citric acid) which promotes a thin oxidizing layer to form on the surface of the metal. This thin layer will help protect the metal from chemical attack.

Fabrication of the metal can reduce the overall corrosion performance of the stainless steel; therefore, making the passivation polishing process an essential step. If iron particles become embedded in the surface of the metal during processing they must be removed. If they are not removed, these microscopic particles may promote discoloration, rusting or even pitting. By dissolving these particles in an oxidizing bath, it will enhance the corrosion resistance of the stainless steel thus fortifying the surface of the metal against such attacks.

The passivation polishing process should be the last step in the fabrication process. It is generally performed by immersing the parts in either a nitric acid or citric acid bath and then rinsing in a clear de-ionized water and then dried. If due to the size of the part it is impractical to immerse the part in a bath, the acid solution may be applied to part using a swab and rinsed with water and dried. It is important that the surface of the steel is free from scale, oils or other lubricants prior to the chemical treatment in order for the passivation cleaning to be effective.

What can be passivated?

HPT can work with you to evaluate your project and determine which parts and pieces should be passivated. All material will be cleaned using industry ASTM standards, inspected by trained personnel, and packaged in our class 10,000 cleanroom on site at HPT.

Components, Parts & Systems that can be cleaned include:

Tube, Pipe, Spools, manifolds, and Fittings
Heat Exchangers
Valves
Fabricated specials
Copper, Carbon, and Stainless Steel

All material mechanically polished and/ or passivated receives a certification of conformance after processing. All components, parts & systems will be mechanically polished/ passivated stainless steel tubing to HPT-500/ HPT-500A specification, inspected, bagged, labeled, and certified.

HPT can also perform mechanical polishing / passivation polishing with expedited lead times to prevent downtime in your system or project.

Contact HPT today to learn more about our mechanical polishing / passivation services or request more information on our mechanical polishing/ passivation cleaning processes.