Jiangyin Donghao Stainless Steel Tubing  
  Portugal | Japanese | Русский | España | Deutsch | English | Chinese Sitemap | Contact US


Stainless Steel

Passivation of Stainless Steel Tube

Stainless steel are designed to naturally self-passivate whenever a clean surface is exposed to an environment that can provide enough oxygen to form the chromium rich oxide surface layer, on which the corrosion resistance of these alloys depends. Naturally occurring conditions such air or aerated water will do this and so under many exposure conditions stainless steel will naturally self-passivate.

Pickling, passivation and removing iron contamination with nitric acid
Passivation treatments are sometimes specified, but it is important to consider whether this is strictly necessary or not. Stainless steel cannot be passivated unless the steel surface is clean and free from contamination and scale from welding operations.

Scale may need to be removed first by 'pickling' or mechanical abrasion and although the surface of freshly pickled stainless steel will normally be immediately passivated once the pickling acid has been washed off, it is important not to regard these two treatments as the same.

Pickling usually involves nitric acids / hydrofluoric acids mixtures, whereas, traditionally passivation has been done using only nitric acid. Nitric acid alone can be used to remove light surface iron contamination after which the acid facilitates the passivation of the cleaned steel surface.

Citric acid passivation as an alternative to nitric acid treatments

Citric acid treatments can also be considered as an alternative to nitric acid as both provide the oxidising conditions necessary for passivation. Citric acid is a less hazardous method and has environmental benefits in terms of 'NOx' fume emission and waste acid disposal. Solution strengths of 4-10% citric acid are specified for passivation treatments in ASTM A967.

Specifications for passivation treatments for stainless steel.

Traditionally the American standards have been used.

These include: -

ASTM A380 - Practice for Cleaning, Descaling and Passivating of Stainless Steel Parts, Equipment and Systems

ASTM A967 - Specification for Chemical Passivation Treatments for Stainless Steel Parts (based on US Defense Department standard QQ-P-35C)

In 1997 an alternative British Standard was published:

EN 2516 - Passivation of Corrosion Resisting Steels and Decontamination of Nickel Base Alloys

Share TubingChina.com All Rights Reserved

Directory | Standard | Heat | Heat Exchanger | Temperature | Pressure | Corrosion | Hardness | Surface | Properties | Selection of Stainless Steel | Contact US

Useful Tools:

Metals weight Calculator
Stainless Steel Weight Calculator
Nickel Alloy Tubing Weight Calculator
Sheet Plate Weight Calculator
Hardness Values Conversion Calculator
Hardness Conversion Calculator
Length Weight Temperature Volume Pressure Conversion
Pipe Working Pressure Calculation
Pressure Conversion Converter Calculator
Gauge Sizes - Wire Sheet Plate Tube
Stainless Steel Pipe Schdule
Nominal Pipe Size
ANSI Pipe Chart

Stainless Steel Tubing and Pipe:

Heat Exchanger Tubes
U Bend Stainless Steel Tubing
Duplex Stainless Steel Pipe
Boiler Tubes, Condenser Tubes
Stainless Steel Seamless Pipes Corrugated Seamless Stainless Steel Pipe Tube
Cold Drawn Bright Annealing Stainless Steel Tubes
Heat resistant Stainless Steel Tubes
Welded Stainless Steel Pipe
Corrosion Resistant Stainless Steel Tube
Corrosion Resistance of Stainless Steel Tubes
Nickel Alloy Seamless Tubes:

UNS N08020 2.4600 Nickel Alloy 20 Seamless Tubing
UNS N02200 2.4066 200 Nickel Alloy Seamless Tubing
UNS N04400 400 Nickel Alloy 2.4360 Nickel Alloy Tubing
UNS N08800 800 Nickel Alloy Seamless Tubes
UNS N08810 800H UNS N08810 Nickel Alloy Seamless Tubes
UNS N08811 800HT Nickel Alloy Seamless Tubes
UNS N08825 825 2.4858 Nickel Alloy Seamless Tubes
UNS N06600 600 2.4816 Nickel Alloy Seamless Tubes
UNS N06625 625 2.4856 Nickel Alloy Seamless Tubes
UNS N10276 C-276 2.4819 Nickel Alloy Seamless Tubing
Why Choose Donghao Steel?

Production Equipment
Testing Equipement
Qualification and Certificates
Quality Control Systerm
Service Range and Procedure

Contact With US:
Tel: +86-159-61185386
Fax: +86-510-86982929