Duplex stainless steel grades are becoming more commonly used in the pulp and paper industry. So let’s take a closer look at some of the benefits of using this material.
Stainless Steel and the Challenging Environment of the Pulp and Paper Industry
There are several steps and pieces of equipment involved in the production of pulp and paper. Each step has some specific conditions that planners need to consider when choosing the best material for the equipment. At each step the machinery, the temperature, the pressure, the amount of movement, and the used chemicals vary. Here are some of the processing steps and the conditions they encounter:
A digester is the machine that manipulates the wood chips that are fed into it. This happens under high temperature and pressure, in order to remove the glue that holds the chips together.
The resulting pulp is then washed several times. This step removes and recycles what we also know as the cooking liquor.
The next step is bleaching the purified pulp. This process determines the brightness of the final paper product.
Once the bleaching process is completed, the pulp is processed into a liquid mash. This is then sent to the paper mill.
The mash goes through a series of wet end and dry end equipment to remove the water and compress the fibers into paper.
Modern pulp and paper processing plants use what a so-called closed loop system. Since the used water is not permitted to be returned to the environment, it is recycled and cleaned several times. After completing this process in accordance with current environmental protection standards the water is safe enough and hence released. Closed loop systems can encounter harsh corrosion conditions. That is why these systems consist of stainless steel now. It is the most corrosion resistant of all the steel products.
Benefits of Duplex Stainless Steel for Pulp and Paper Processing
Duplex stainless steel is a metal that combines ferritic and austenitic stainless steel grades. Common grades of duplex stainless steels include 2205 and 2507. Duplex steels has some impressive properties that compliment the requirements of new and upgraded pulp and paper mills. There are some specific properties that make duplex stainless steel better suited for this industry than other steels.
These include: Corrosion Resistance – High Strength – Design Flexibility – Cost Savings
Corrosion Resistance: As mentioned above, duplex stainless steel has excellent corrosion resistance properties. It does not succumb easily to stress cracks, pitting, or abrasion.
High Strength: Duplex stainless steel profiles and special shapes have nearly twice the strength of austenitic stainless steel, resulting in cost savings due to lower material weights.
Design Flexibility: Stainless steel is somewhat easy to machine and weld. Hence, it is allowing for production of a variety of standard stainless steel beams, channels, and angles, as well as special shapes.
Cost Savings: While using duplex stainless steel profiles may initially cost more than carbon steel, the cost savings over time for less corrosive materials may be an incentive to use stainless steel. Maintenance, inspection, and repair costs will be greatly reduced.
Laser Fusing Duplex Steel Sections
At Stainless Structurals, we use a laser fusion technology process for our customized stainless steel shapes. The advantage of this process is the ability to make precise cuts. Furthermore, we can fuse sections together with extremely small weld beads that do not have any filler material. This high-end technology allows for close monitoring of the cooling process while still maintaining superior corrosion resistance. We achieve exceptional accuracy by using highly concentrated thermal energy of the laser. With this technology, we are able to produce standard and special profiles in duplex stainless steel, including 2205 and 2507 grades. The process assures stainless steel profiles that have precise, clean lines and square corners. Those we can also weld tightly together and customize especially to meet the specific demands of the pulp and paper industry.
The pulp and paper processing equipment is subject to immense stress, such as corrosion, temperature extremes, pressurization, and harsh chemicals. The welds in carbon steel can more easily deteriorate from such exposures. The precise and tight welds of laser fused shapes are less likely to succumb to such stressors.
An Industry Leader in Stainless Steel Profiles for Manufacturing
Stainless Structurals is an international leader in the structural steel industry. Our laser fused duplex steel sections are of the highest quality and standards. The accuracy we employ during production, paired with the durability of the finished products, make our stainless steel profiles a great match for the unique demands of the modern pulp and paper industry. We invite you contact us to obtain more information about our worldwide products and services.