Waverley Brownall

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Nitric Acid Resistant Materials

Nitric Acid Resistant Materials

Due to its strongly oxidising nature, HNO3 (Nitric Acid) attacks most metals, causing localised corrosion issues.

Exposure to concentrated Nitric acid or acid at a high temperature can cause intense attack in particular areas on the surface of a metal, also known as pitting.

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Nitric Acid: Stainless Steel Exception

For nitric acid, stainless steel 304 is often used in a replacement for 316, which is the opposite solution for most corrosion resistant tactics (for nitric.)

The British Stainless Steel Association recommends for over 95% concentration that aluminium alloys can be considered.

Please see the table below for an overview of nitric acid resistant materials and their effectiveness against attacks.

According to the “Materials Selector for Hazardous Chemicals, Vol. 5: Nitric Acid” published by MTI,

304L material is preferable over standard 304to avoid sensitisation.

Nitric Acid Resistant Materials Charts

nitric acid resistant materials

1 – Available for use
2 – Use with caution to concentration, temperature and pressure
3 – Do not use

302 and 304 stainless steels – 1
316 stainless steel – 2
Monel – 3
6MO stainless steel – 2 (Can provide greater protection in certain circumstances due to its higher chromium content.)
Hastelloy C276 – 3
Titanium – 1 (Advantage based on its strong oxide film when exposed to any oxidising substance.
)Inconel 625 – 2 (Good resistance but no initial benefit to 825 alloyunless other acids are present.)
Incoloy 825 – 1

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Why Incoloy 825 Is A Powerhouse Against Nitric Acid

UNS N08825, also known as Incoloy or alloy 825, is one of the best metals to use in areas of Nitric acid corrosion.

Its chromium content allows a resistance to a variety of oxidising substances, with broad usefulness in higher temperatures.

Alloy 825 is used within industries that require all-round hardiness when exposed to strong substances.

These industries include the nuclear sector and acid production. The chromium content of 825 is 19.5-23.5, with other elements being 38.0-46.0 Nickel, 0.6-1.2 titanium and 2.5-3.5 molybdenum.

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The types of corrosion that 825 can withstand include pitting, crevice corrosion, intergranular corrosion and SSC.

Due to its natural machinability at the annealed temper, Waverley Brownall is able to manufacture incoloy 825 fittings and valves to supply the chemical processing and food industries.

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Remember that metals will react variably towards nitric acid according to concentration levels, temperatures, pressures and nature of metals.

Caution must always be taken when applying fittings, tube or valves into areas where nitric acid is present. Professional advice on the ideal material choices to work with nitric acid should be sought if there are no indicators within a company’s handbook.

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Corrosion Prevention Material Selection

Corrosion Prevention Material Selection

The issue of corrosion within industries such as oil and gas, chemical processing and marine engineering is extremely important.

To avoid extreme health and safety issues and economic loss, businesses within these industries must be one step ahead of the corrosive media in the working environment.

Solutions for corrosion resistance are available in forms of coatings, but for long-term investment in corrosion resistance, material selection is the number one prevention tool.

Corrosion Prevention Material Selection: The Importance To All Industries

Selecting the correct material to withstand destructive acids, oxygen and waters is the key to avoiding disasters.

This is not only a consideration for economic factors, but industries must prevent disasters on a huge scale that include loss of life, such as the Guadalajara Sewer Explosion. This explosion resulted in the death of 215 people, with 1,500 injured and damage to 1,600 buildings within the surrounding area. You can read more about the explosion in this post on Some Of The Worst Cases Of Corrosion.

Prevention Of Corrosion

Topics covered in this Slideshare include corrosion prevention methods and the considerations regarding material selection for corrosion prevention efficiency.

Slideshare presentation original works by Professor TKG Namboodhiri,
Consultant in Metallurgy and Corrosion

Corrosion Prevention Material Selection

Materials that are used for their corrosion resistance are often called high-performance alloys, special metals, exotic alloys or exotic metals.

Special Metals (Corrosion-Resistant Metals)

Some metals hold the properties to withstand corrosive environments, alongside issues of pitting, stress-corrosion cracking and more. These metals are more expensive than a standard stainless steel, but they can provide strength within environments with acids, alkaline, salts and seawater.

Not every company can have a qualified metallurgist at hand, luckily, there is plenty of information available from the original creators of certain special metals available online. Such as, Haynes International’s information on the alloy Hastelloy-C276.

Waverley Brownall also offer a free book to help guide you in the selection of our range of special metals for extreme applications. This includes information on the main considerations such as availability, metal composition and corrosion resistance charts for a clear view of a metals resistance in comparison to each other.

Considerations For Metal Selection

  • Cost of investment (Short term VS. Long term)
  • Properties of material needed
  • Application of material
  • Product of material (Eg. Fittings, Valve)
  • Design
  • Material VS. Material comparisons to find the best solution
  • Technical advice
  • Industry requirements and regulations

Materials With High Corrosion Resistance

Metals that hold high-corrosion resistant properties include: Incoloy 825, Inconel 625, Hastelloy C-276, Titanium, Super Duplex, Duplex, 6MO. You can find out more about these on our special metals page.

Learn More With A Free Guide

This guide covers everything you need to know for selecting the right corrosion resistant material for our entire range of valves and fittings.

A Guide In The Selection Of Special Metals

*Posted FREE to your address

GET MY GUIDE
  • Corrosion charts
  • Applications
  • Strengths
  • Alloy properties and Composition

Corrosion Resistant Alloys In Oil And Gas Production

As an approved supplier to Conoco Phillips, BP and Shell, we fully understand the need for correct corrosion prevention material selection within Oil and Gas. Metals within an environment such as this are expected to thrive with external attacks from severe application and heavy usage over a long period of time. This is why we have specialised in manufacturing fittings and valves in special metals to not only cope in these conditions, but to provide the biggest value to engineers around the world.

nuclear power plant

Other Industries

  • Chemical
  • Processing
  • Purification/Water
  • Agriculture
  • Pump and Valve
  • Petroleum
  • Renewable Energy
  • Nuclear

Helpful Links

Contact Us

enquiries@waverleybrownall.co.uk

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Titanium Used On Juno SpaceCraft

Titanium Used On Juno SpaceCraft

The spin-stabilised spacecraft Juno has been built with the mighty task to orbit planet Jupiter.

NASA have issued fantastic information reagrding the spacecraft and its travel – including the ability to track Juno’s position using their website. ​

Launched near 5 years ago, we’re right on time as Juno enters orbit around Jupiter.

Titanium And The One Giant Leap For Mankind

This alloy has long been known for its incredible strength.

juno spacecraft jupiter

It provides fantastic resistance to challenges on our planet – such as seawater corrosion.

However, one area we rarely hear about is its durability on spacecraft structures.

Titanium has high strength compared to its weight, but this isn’t the only reason why it is used so often in the aerospace industry.

​The Properties Of Titanium

This metal has the ability to withstand some very high temperatures. As you can imagine, in space, it is essential for materials ​to withstand incredible atmospheric pressures. Although Juno won’t face the same temperature problems as low-Earth orbiting crafts and satellites will, it will be experiencing a lack of sun radiation.

At the centre of Juno, sits the vehicle’s electronics vault that protects the precious electrical set-up from the harsh environment surrounding it. ​Juno will need to endure not only cruising through deep-space, but it will need to endure flying through Jupiter’s intense radiation belts.

Juno’s radiation vault is made of titanium alloy with a thickness of one centimeter.​

The top deck of Juno is planned to receive a radiation dose of 22 Mrad, showing the amazing shielding capability of the vault.

Titanium In Space

Did you know?

Titanium Grade 2

titanium grade 2 alloy

Waverley Brownall are proud manufacturers of fittings and valves in Grade 2 for uses in the aerospace, oil and gas, chemical and processing industries.

For more information on our special metals, email: enquiries@waverleybrownall.co.uk