Oops! It appears that you have disabled your Javascript. In order for you to see this page as it is meant to appear, we ask that you please re-enable your Javascript!

Are you Looking to Buy Stainless Steel Sheets, Plates, Coils, Strips? Call Us Now! +919892451458, +919833604219, +912223894219

How to Calculate PREN Value of Alloys? What is the PREN for Stainless Steel Materials?

//How to Calculate PREN Value of Alloys? What is the PREN for Stainless Steel Materials?

How to Calculate PREN Value of Alloys? What is the PREN for Stainless Steel Materials?

Source: International Molybdenum Association - PREN Comparison of Stainless Steel and Duplex Steel Materials

Source: International Molybdenum Association – PREN Comparison of Stainless Steel and Duplex Steel Materials

Pitting Resistance Equivalent Number (PREN) is generally used to indicate the pitting resistance of stainless steels. In general: the higher PREN-value, the more corrosion resistant the steel. A PREN of 32 is considered the minimum for seawater pitting resistance. Furthermore a PREN-value ≥ 40 for duplex steels is called for in the DIN EN ISO 15156 as well as the American NACE – a standard for use in hydrogen sulfide environments known in the oil and gas extraction industries.

PREN is calculated as follows for austenitic stainless steel and duplex stainless steel respectively:

  1. PREN=%Cr+3.3×%Mo+16×%N
  2. PREN=%Cr+3.3×%Mo+30×%N

This formula suggests that molybdenum is 3.3 times more effective than chromium at improving pitting resistance, which is true within limits. Chromium must always be present in stainless steel to provide basic corrosion resistance. Molybdenum cannot provide this basic resistance, but it significantly enhances a stainless steel’s corrosion resistance, as the formula shows.

The table shows that ferritic, austenitic and duplex stainless steels with different levels of pitting resistance are available, and the figure below shows that it is possible to select several different grades with similar pitting resistance. For example Types 444 (ferritic), 316 (austenitic) and 2304 (duplex) have similar resistance to pitting corrosion in chloride environments.

PREN Values for Various Grades of Stainless Steels

Grade EN No/UNS Type Typical PREN
430 1.4016/ Ferritic 18
S43000
304 1.4301/ Austenitic  19
S30400
441 1.4509/ Ferritic 19
S43932
RDN 903 1.4482/ Duplex  22
S32001
316  1.4401/ Austenitic  24
S31600
444 1.4521/ Ferritic 24
S44400
316L 2.5 Mo 1.4435 Austenitic  26
2101 LDX  1.4162/ Duplex 26
S32101
2304 1.4362/ Duplex 26
S32304
DX2202 1.4062/ S32202 Duplex 27
904L 1.4539/ Austenitic 34
N08904
2205  1.4462/ Duplex 35
S31803/
S32205
Zeron 100  1.4501/  Duplex 41
S32760
Ferrinox 255/ 1.4507/  Duplex  41
Uranus 2507Cu S32520/
S32550
2507 1.4410/ Duplex 43
S32750

Metline Industries is a leading stockholder and processor of aluminium, nickel, titanium and stainless steel alloys in various forms including pipes, plates, fittings, flanges, and relate piping accessories. We are ISO certified company, with exports to over 50 countries worldwide. Our key products include stainless steel plates, stainless steel sheets, stainless steel pipes, stainless steel pipe fittings, stainless steel bars, stainless steel angles, stainless steel rods and stainless steel flanges. We are India’s leading manufacturer of pipes fittings, with exports to Amercia, Europe, Saudi Arabia, Qatar, Kuwait, and various other Middle East Nations.


 

By |2017-07-26T11:43:34+00:00June 24th, 2017|Stainless Steel|0 Comments