The Benefits of Using High-Quality Materials in Asian Fertilizer Production

By Vikram Pandit, Technical Marketing Manager, BU Tube APAC

Increasing demands for food from less arable land to support expanding populations in Asia Pacific means the fertilizer market in the region is set for significant growth.

The region’s fertilizer market was valued at $9.3 billion in 2020 and is expected to register a compound annual growth rate (CAGR) of almost 7% over the next five years.

At the same time, players in the fertilizer industry are continually seeking ways to improve efficiency and productivity while simultaneously reducing maintenance costs and unscheduled downtime.

Urea is a critical component of common fertilizers, and its production occurs in extremely corrosive, high pressure, and high temperature conditions. Using quality materials that can withstand these conditions can deliver tangible benefits for plant operators and asset managers.

Sandvik 2RE69 from Sandvik Materials Technology is a fully austenitic stainless steel with extra low carbon and impurity contents, including low ferrite content. It differs from the original 25.22.2 steel grade, which was developed several years ago primarily to combat the severe corrosive conditions in the urea industry.

The longest life service so far for Sandvik 2RE69 is 36 years, which confirms its optimal properties for application in urea strippers. Used in the outer layer of bimetallic stripper tubes, ferrules, and carbamate condensers, the main characteristics of Sandvik 2RE69 include:

  • Excellent resistance to corrosion in ammonium carbamate and nitric acid
  • Excellent resistance to intergranular corrosion
  • High resistance to pitting and crevice corrosion and good weldability

To compare the performance of Sandvik 2RE69 against conventional 25.22.2 grades, it’s important to explore their chemical compositions and test results.

Grade

C

S

P

Si

Mn

Cr

Ni

Mo

2RE69

≤0.020

≤0.010

≤0.015

≤0.4

1.7

25

22

2.1

Standard 25.22.2

0.020

0.010

0.020

0.4 max

1.5-2.0

24-26

21-23.5

2-2.6

Typical chemical composition

The higher nickel content of Sandvik 2RE69 has various benefits: it ensures a more austenitic structure, helps the formation of a passive chromium-oxide film and increases resistance to stress corrosion cracking. It also makes the material resistant to wet and high-temperature corrosion.

The grade’s lower carbon levels mean good corrosion resistance and better weldability. Lower sulfur and phosphorous mean lower impurity levels which greatly improves the performance of the tube in ammonium carbamate solutions.

Corrosion test results

The Huey corrosion test is used by all licensors as an acceptance and rejection criteria for urea applications. Tube samples are kept in a 65% nitric acid solution for 48 hours, repeated for 10 cycles, and the loss of weight is measured.

The maximum limit of corrosion for 25.22.2 is 0.18 mm a year as specified by the licensors. However, Sandvik 2RE69 guarantees a maximum corrosion rate of just 0.12 mm a year, which extends the material’s life in actual process conditions, supports increased production, and lowers overall operational costs.

The table below compares the corrosion rate of Sandvik 2RE69 to conventional 25.22.2 steel when used in a stripper application.

Sandvik 2RE69 usage

Through extending equipment life, reducing downtime and maintenance costs, improving productivity, and lowering production costs, Sandvik 2RE69 is established as a preferred material for use in ammonium carbamate services for fertilizer production.

The material can be supplied in:

  • Plates
  • Tubes and pipes
  • Welding consumables
  • Bars
  • Fittings and flanges

The materials proven track record make it a popular choice in urea plants across the world for carbamate condenser tubing. Want to find out more about the Sandvik 2RE69? Visit here.

Read more about the case story here.

vikram-pandit.jpgName: Vikram Pandit
Title: Technical Marketing Manager
Business Unit: Tube APAC
Location: India