Corrosion Prevention in Your Filter Press Operation

Cast Iron Filter Press replaced with a Micronics Stainless Steel Press

In the mid-1800s and into the mid-1900s, many manufacturers would construct their press frames with cast iron. Although cast iron was a good option for the time, with the arrival of the modern steel revolution in the 1850s, manufacturers soon began using Carbon Steel to construct rugged, durable Filter Press frames. Carbon Steel is a steel alloy where Carbon is the main alloying element. Typically, Carbon Steel contains up to 2.0% Carbon by weight, along with the minute presence of other alloying elements such as Mn and Si. While stainless steel is often used in extremely harsh or specialized environments – and Micronics has a great deal of experience with press fabrications made with stainless steel – Carbon Steel is used most often in filter press construction.

Carbon Steel, the most widely used engineering material, accounts for approximately 85%, of the annual steel production worldwide! As a consequence of its wide use as an engineered material, the Micronics Engineered Filtration Group service team advises being knowledgeable about the operating conditions that can cause harm to Carbon Steel and, in particular, Carbon Steel Filter Press Frames. A particularly important condition that we will focus on in this blog is the corrosion of carbon steel, which can play a key role in filter press failures.

Identifying that you have a corrosion problem is the first step in correcting the problem.

There are many different types of corrosion that are visible to the naked eye and visual inspection is a key to maintaining excellent filter press operating performance. We will examine several types of corrosion seen in the Filter Press Industry: Uniform Corrosion, Pitting Corrosion, Crevice Corrosion, and Filiform Corrosion.

Uniform Corrosion

In general, uniform corrosion is the most common type of corrosion. It can be defined as the attack of the entire metal surface exposed to the corrosive environment.

Pitting Corrosion

Pitting corrosion, or pitting, is a form of extremely localized corrosion that leads to the creation of small holes in the metal. Pitting can be initiated by a small surface defect or damage to the protective paint coating. Unprotected cylinder rods often have pitting which damages the cylinder wiper seals and transfers the moisture into the cylinder, pitting the cylinder walls.

Pitting corrosion can also help initiate stress corrosion cracking so monitoring for pitting is an absolutely essential ingredient in filter press maintenance and repairs and ensuring long filter press life.

Crevice Corrosion

Crevice Corrosion refers to the localized attack on a metal surface at, or immediately adjacent to, the gap or crevice between two joining surfaces. Crevice corrosion in filter presses is mainly found in the joggle areas, where the sidebars meet with the feed head and crosshead. It is initiated by changes in local chemistry within the crevice such as a shift to acid conditions in the crevice or the build-up of aggressive ion species (e.g., chloride) in the crevice. This type of corrosion in filter presses can potentially lead to major catastrophic failure.

Filiform Corrosion

Filiform Corrosion, a special form of Crevice Corrosion, is specific to painted steel, aluminum, and magnesium surfaces. Filiform Corrosion normally starts at small, sometimes microscopic, defects in the coating. It results in a detachment of the coating from its metallic support, which is caused by the surface corrosion of the underlying metal at the metal/coating interface. Early signs are chipping or cracking paint.

Corrosion Protection for Filter Presses

Did You Know…an appropriate and properly applied paint finish is an important part of corrosion prevention in your filter presses? Micronics paints all carbon steel with an epoxy-based paint to reduce corrosion and increase surface durability. Our press painting by trained operators also ensures superior fade resistance, sound dampening, provides resistance to a variety of strong chemicals, and is 50-state compliant. We also coat all our drip tray assemblies with a thick, rubberized epoxy that prevents damage from impact, adding a high level of corrosion resistance. We offer many components in various grades of stainless steel from frames to wear parts to ensure superb performance under many operating conditions.

Monitoring & Maintenance: Routine Visual Inspections of Your Press – Whether 630mm, 800mm, 1200mm, or 1500mm – Are Keys to Corrosion Prevention

Maintaining a proper inspection schedule is vital to the proper operation and long life of your Filter Press. We encourage you to contact us to schedule an on-site inspection of your filter press or filter presses with a highly-experienced Micronics Field Service technician. Micronics technicians are experienced and trained in the inspection of filter presses for all the types of corrosion detailed here including Uniform Corrosion, Pitting Corrosion, Crevice Corrosion, and Filiform Corrosion. We will inspect your filter press frame for you and recommend corrective actions.  

Micronics’ onsite inspections also include a complete inspection of the following items, along with a full report of our findings:

• Filter Press Frame
• Plate Stack
• Hydraulic Power Pack
• Hydraulic Cylinder
• Drip Trays
• Plate Shifters
• Cloth Washers
• Membrane Squeeze Systems

With a large worldwide installation base of Micronics’ own heavy-duty Filter Presses – and a hands-on sales and service team that supports a wide range of other OEM filter presses where we supply industry-leading filter cloth, filter press parts, and provide press service – our team is uniquely qualified to visit your site to perform an audit of your Filter Press system or systems and provide invaluable, experience-based recommendations.

You can rely on Micronics for helping ensure your facility doesn’t experience a catastrophic failure, either of an aging press or of a press operating in a highly-corrosive environment.

Contact Us and take no chances when it comes to corrosion prevention. Our Sales, Service, and Engineering teams are here to ensure your success with all your filtration needs.