Pipe corrosion costs you money and productivity. Monetary costs come from direct damage from leaks, indirect damage from lost work and regular maintenance of pipe and fittings.
To prevent losses from corrosion and the damage it causes, you must know why it happens in industrial pipe and fittings. With basic prevention, you can save your facility the time and lost work of broken or leaking pipes.
Why Corrosion Occurs in Industrial Settings
In industrial settings, corrosion happens when metal breaks down as energy transfers from one material to another. The type of corrosion depends on the metal and environmental conditions. Several types of corrosion exist – galvanic, chemical, electrical, microorganism and stress crack. Each has its own reason for occurring and means for prevention.
1. Galvanic Corrosion
Galvanic corrosion may occur when dissimilar metals adjoin with a conducting material between them. One of the metals will stay protected while the other corrodes. This form of corrosion often occurs when a more refined, high-energy metal, such as iron, passes its energy to a less refined metal, like copper, through the environment.
Soil and water can both carry energy from one metal to another, leading to corrosion. The higher energy metal will become an anode and contribute electrons to the lower energy metal, which acts as the cathode. This movement of electrons leads to the corrosion of the high-energy metal and protection of the low-energy one.
Setting up sacrificial anodes near steel pipes or other metals protects the pipe by converting it into a cathode, while the sacrificial metal anodes corrode.
Acid attacking the metal piping creates chemical corrosion. Typically, this may happen at facilities that handle strong chemicals with low pH values. Often, the chemical wear happens under the insulation of the piping. Protecting the metal from chemical contact is critical in preventing pipe corrosion of this type.
Pipes exposed to AC or DC current may experience corrosion. Pipes underground running near trolley lines with DC power or high-voltage electric lines with AC current may corrode from the electricity flowing through the pipe and leaving through the soil. Where the pipe changes direction, the current which had moved along the pipe in a straight line leaves and flows through the soil. The turning point of the pipe typically is where the corrosion occurs.
Some microorganisms can directly attack the metal inside pipes by consuming the material itself. Another way bacteria damage pipes and fittings is through the chemical byproducts they produce. Either of these methods eats into the metal, and to prevent the damage, you need antimicrobial products inside the pipe.
5. Stress Crack
Cracking along the grain of metal is a form of stress-induced corrosion. Most often, this form of damage occurs in high-strength metals when conditions meet a series of requirements – corrosion-likely environment, high-tensile stress and an alloy prone to the stress. Damage typically forms along the grain lines as corrosion reduces the metal’s resistance to cracking.
Pitting vs. Crevice Corrosion
When it comes to the differences between crevice and pitting corrosion, there is a fine distinction based on the location of the damage and conditions that caused it.
Pitting happens at random locations along the surface of the metal. Most often, this happens in areas of slow flow or stagnant liquid. Understanding this form of damage is crucial when working to prevent liquid handling corrosion. Keeping fluids moving through pipes can reduce the chances of pitting corrosion.
Though the appearance of crevice corrosion resembles the pits seen in the pitting form of damage, the location will determine if you have crevice or pitting corrosion. This form of pipe corrosion happens at junctures between pipe and fittings such as at bolts, joints and gaskets.
How to Prevent Corrosion
While some causes of pipe corrosion are easier to prevent than others by keeping the conditions that cause the damage at bay, you still need to take action to stop all forms of damage. Prevention is the key to avoiding the costly damage from breaches in the pipe structure. With good care and prevention, pipe, even heavily used petroleum pipelines, can last for decades.
1. Preventative Maintenance
Preventative maintenance that includes inspections goes a long way toward keeping pipe and fittings intact.
Whether dealing with chemical or water pipe corrosion, the type of pipe and fittings will determine the form of prevention you need to take. For example, galvanic corrosion prevention may require the inclusion of a sacrifice metal. To keep microorganism-caused damage away, treat the fluid inside the pipe with antimicrobial substances. Keeping your pipes safe from chemical erosion may require the use of lined pipe. Keeping metal pipe and fittings away from electrical sources such as underground power lines will prevent electrical damage.
If using dissimilar metals for pipe and fittings, you must insulate the two metals from each other to prevent currents from flowing between the metals and causing corrosion.
2. Select the Right Material for Your Operation
Choosing the correct material to prevent both internal and external corrosion is another critical step to make. When it comes to lined pipe, you have multiple options to choose from. However, some options perform better at preventing corrosion than others in certain circumstances.
To keep chemical corrosion away, use polyvinylidene fluoride (PVDF) lined pipe and fittings. This material has a high resistance to chemical damage. It can also handle a wide range of temperatures from -140 degrees Fahrenheit to 275 degrees Fahrenheit. You may also use this to stay within USDA and FDA regulations for food-handling products.
For resistance to almost all chemicals and temperatures up to 450 degrees Fahrenheit, use the multipurpose polytetrafluoroethylene (PTFE) lined pipe and fittings. This premium lined piping keeps products inside pure while preventing leaks and corrosion due to its outstanding resiliency.
As an alternative to Resistoflex PTFE-lined pipe, use Resistoflex ALT PTFE-lined pipe and fittings. This lining offers even greater resistance to corrosion and up to 60% more protection against permeation. Its designer specifically made this lined piping to hold up to the most rigorous industrial fluid handling needs of power plants and pulp and paper making facilities.
Not all industrial applications require the strongest lining inside piping. For a more economical option that can handle temperatures up to 225 degrees Fahrenheit, use polypropylene (PP) lined pipe.
Locate a Lined Pipe and Fittings Supplier
Preventing pipe corrosion will save you direct and indirect costs from leaks. While regular maintenance helps, having the right pipe and fittings does more to delay industrial piping corrosion. To move forward with your business, you must correct any problems causing delays in operations, including replacing old, worn pipe and fittings with lined alternatives to resist future damage from corrosion. Lined pipe and fittings from SEMCOR are key to maintaining your facility’s efficiency. Whether your operation needs an off-the-shelf solution or a part modified to fit your needs, contact us at SEMCOR.