Menu
Search
Filters
Close
Menu

06221 ALLOYS SUITABLE FOR PHOSPHORIC ACID APPLICATIONS

Picture for 06221 ALLOYS SUITABLE FOR PHOSPHORIC ACID
Available for download

This work reports on the success achieved with alloy 31 in critical parts of the phosphoric acid process. Laboratory results are presented together with field experience and examples of application.

Product Number: 51300-06221-SG
ISBN: 06221 2006 CP
Author: Helena Alves, D.C. Agarwal, Antoine Hoxha, Friedrich Stenner
Publication Date: 2006
Industry: Materials Selection and Design
$0.00
$20.00
$20.00

More than 95% of the world demand for phosphoric acid is met by the wet-process, which involves the reaction of the phosphate rock with concentrated sulfuric acid. Pure phosphoric acid is only mildly corrosive to metals. However, the presence of impurities in the phosphate ores like chlorides, fluorides and silicates and the free sulfuric acid lead to complex corrosive conditions. The level of impurity depends on the origin of the phosphates and their processing, e.g. washing the ores with sea water further increases the level of chlorides. The corrosive attack is further aggravated by erosion resulting from the presence of phosphate rock particles and gypsum crystals, turbulence and deposit formation. Equipment for production and handling of phosphoric acid typically consists of rubber lined steel, AISI 316L type stainless steel and special steels like 904L and 28. For the most severe conditions nickel based alloys are used.

Even though material selection has been continuously optimized, sufficient advantage is not being taken from the new, cost-effective 6%-molybdenum alloy 31 (UNS N08031) yet. This high Cr and Mo containing austenitic steel was designed to fill the gap in cost and performance between stainless steels and nickel alloys and significantly improves service life and reduces failure by localized corrosion when its lower alloyed counterparts are at the end of the usefulness limits.

This work reports on the success achieved with alloy 31 in critical parts of the phosphoric acid process. Laboratory results are presented together with field experience and examples of application.

 

Keywords: alloy 31 (UNS N08031), phosphoric acid, 6% Mo alloys, localized corrosion

More than 95% of the world demand for phosphoric acid is met by the wet-process, which involves the reaction of the phosphate rock with concentrated sulfuric acid. Pure phosphoric acid is only mildly corrosive to metals. However, the presence of impurities in the phosphate ores like chlorides, fluorides and silicates and the free sulfuric acid lead to complex corrosive conditions. The level of impurity depends on the origin of the phosphates and their processing, e.g. washing the ores with sea water further increases the level of chlorides. The corrosive attack is further aggravated by erosion resulting from the presence of phosphate rock particles and gypsum crystals, turbulence and deposit formation. Equipment for production and handling of phosphoric acid typically consists of rubber lined steel, AISI 316L type stainless steel and special steels like 904L and 28. For the most severe conditions nickel based alloys are used.

Even though material selection has been continuously optimized, sufficient advantage is not being taken from the new, cost-effective 6%-molybdenum alloy 31 (UNS N08031) yet. This high Cr and Mo containing austenitic steel was designed to fill the gap in cost and performance between stainless steels and nickel alloys and significantly improves service life and reduces failure by localized corrosion when its lower alloyed counterparts are at the end of the usefulness limits.

This work reports on the success achieved with alloy 31 in critical parts of the phosphoric acid process. Laboratory results are presented together with field experience and examples of application.

 

Keywords: alloy 31 (UNS N08031), phosphoric acid, 6% Mo alloys, localized corrosion

PRICE BREAKS - The more you buy, the more you save
Quantity
1+
5+
Price
$20.00
$20.00
Product tags
Also Purchased
Picture for 04233 Alloy Selection for Dilute and Medium
Available for download

04233 Alloy Selection for Dilute and Medium Concentration Sulfuric Acid

Product Number: 51300-04233-SG
ISBN: 04233 2004 CP
Author: Ulrich Brill and Helena Alves, ThyssenKrupp VDM GmbH
Publication Date: 2004
$20.00

Sulfuric acid is one of the most important elementary substances of the chemical industry.  There is no stainless steel or even a nickel base alloy available which is suitable over the entire concentration range.  This paper will give corrosion data in up to 75 % sulfuric acid at boiling temperature for various commercial grades as well as for some new developmental alloys.
Picture for 04231 Effect of Chloride and Phosphoric Acid
Available for download

04231 Effect of Chloride and Phosphoric Acid on the Corrosion of C-276, UNS N08028, and UNS N08367

Product Number: 51300-04231-SG
ISBN: 04231 2004 CP
Author: Sukanta Ghosh and Thodla Ramgopal, GE India Technology Centre Ltd.
$20.00
Picture for 04221 A New Nickel Alloy Resistant to "Wet
Available for download

04221 A New Nickel Alloy Resistant to "Wet Process" Phosphoric Acid

Product Number: 51300-04221-SG
ISBN: 04221 2004 CP
Author: Paul Crook and Martin Caruso, Haynes International Inc.
$20.00
Categories
Industry
Recently viewed
Popular tags
View all

Association for Materials Protection and Performance

© AMPP All Rights Reserved.
Membership Terms of Content Use
Contact Customer Support