All industrial processes – be it food processing, wastewater treatment, energy, manufacturing, paper, oil refineries or more – require pumps to operate efficiently. All industrial processes and applications require liquids to be pumped at some point in the process. From deep sea oil and gas explorations to wastewater treatment plants, all industrial applications use pumps to perform a wide range of tasks. As an industrial plant owner, it’s essential that you minimize downtime and operational costs, by boosting the reliability and efficiency of all the pumps you use in your plant. One of the biggest drawbacks for industrial pumps is – erosion and corrosion. Industrial pumps, unlike domestic pumps, operate in harsh environmental conditions and face a continuous threat from erosion and corrosion. Here, in today’s post, we take a look at how modern industrial centrifugal pump manufacturers like Sintech use the latest pump designs and coating technologies to improve the long term performance of your industrial pumps, by combating erosion and corrosion.
How does Corrosion Occur in Industrial Pumps?
Corrosion is a chemical reaction that occurs between the pump’s surface and the fluid that passes through it. It is of different types – uniform or general corrosion (that occurs all through the pump’s surface) and localized corrosion (that occurs in specific parts of the pump like crevice and pitting).
Generally, metals that are prone to oxidation suffer from localized corrosion, whereas metals like stainless steel suffer from uniform corrosion.
Another important type of corrosion in industrial pumps is FAC (Flow Accelerated Corrosion). This is the process of removal of the oxide layer from a metal’s surface. FAC depends on several factors like the flow velocity of the fluid, oxygen content and chloride levels. Generally, FAC occurs only in pumps that are made from cast iron and low carbon steels. You can easily eliminate FAC by using stainless steel or increasing the chromium content in the pump.
How does Erosion Occur in Industrial Pumps?
When the fluid being transferred contains abrasives like sand, dust and other fine particles, it can cause the pump to erode especially when the flow velocity is high. Erosion is a commonly occurring phenomenon in the injection pumps used in the oil and gas industry. In undersea oil and gas explorations, the pressure must be high to force the water back into the oil field. The entrapped sand particles at these high pressures erode the pump and affect its efficiency.
You can reduce erosion in three ways:
- Reduce the flow velocity in all parts of the pump
- Design the pump, so that flow velocity doesn’t increase to high levels
- Use erosion resistant coating materials for the pumps
Impacts of Erosion and Corrosion on Your Pumping System
In industrial applications, where both erosion and corrosion are present, it can cause degradation of the pump mechanism quickly. Corrosion may create oxide layers that are prone to erosion. On the other hand, erosion may bite into the passive underlying layers, which in turn, accelerates corrosion.
When your pump undergoes erosion and/or corrosion, it affects the overall efficiency of your pump system. This, in turn, leads to increased downtime for repair and maintenance, which in turn, reduces your industrial output while increasing operational costs.
How to Prevent Erosion and Corrosion of Industrial Pumps?
You can prevent the harmful effects of erosion and corrosion on your industrial pumps in two major ways.
1. Choose the Right Materials for your Pump
By choosing the right materials for the construction of your pump, helps to mitigate the problems faced due to erosion and corrosion.
For example, if you are looking to purchase cast iron or carbon steel pumps to reduce the overall costs, make sure to factor in the corrosion rate to the maintenance costs. If the maintenance cost calculated after including the corrosion rate is acceptable, you can choose pumps made of carbon steel or cast iron.
If this maintenance cost is beyond your budget, it makes sense to pay extra and purchase pumps made from stainless steel and other materials that have a long shelf life. While some grades of stainless steel is more corrosion and erosion resistant, it can become susceptible to corrosion if the passive layer is damaged. When the passive layer (outer layer) is damaged, the base layer gets activated, which then starts to corrode.
Another main reason for erosion and corrosion effects in stainless steel pumps is because of stagnant conditions. Similarly, if the chlorine level in the displaced fluid is high, it can have a corrosive impact on a stainless steel pump.
2. Protective Coatings
By using advanced coating technologies, you can significantly improve the durability and performance of your industrial water pumps.
Generally, coatings like Fusion Bonded Epoxy, a polymeric coating can be applied to pump components to reduce the effects of corrosion and erosion. Furthermore, polymeric coatings also improve the hydraulic performance of the pumping process.
With that said, polymeric coatings don’t work well for applications that have high flow velocities. In such cases, you can opt for galvanic protection to reduce the effects of corrosion and erosion.
Another popular coating is carbide coating. Tungsten along with nickel, cobalt, and chrome are used to provide corrosion resistance. With significant advances in coating technologies, you can now choose bespoke coatings that are tailor-made for your specific application requirements.