It’s essential in any application that uses gaskets and seals that the right materials are chosen. Ensuring compatibility not only provides peace of mind that leaks are prevented, but by ensuring the correct material, you can also help to prevent excessive corrosion.
This is of significant importance when it comes to flange faces, as flange face corrosion can lead to leaks, downtime (which is always costly for businesses), and, adding to this expense, costly repairs.
To prevent corrosion and reduce these risks, you will need a sealing solution that is appropriate in design and material to minimise corrosion.
These are often in the form of flange insulation sets, which we’ll explore in more detail throughout this post, as well as how to identify issues before they become a bigger problem.
Flange corrosion
Flange face corrosion is most apparent in metal pipelines, and unfortunately, when corrosion begins, it leads to lower performance and, if left unrepaired, equipment failure.
Corrosion flange often occurs at the interface between adjoining pipes, where the flange faces meet.
It is vital to prevent this from happening to ensure efficiency remains high and shutdowns and downtime are minimised as a corroded flange can pose a significant problem, causing:
- Pitting, galvanic, and crevice corrosion which can all attack various sections of the pipeline, resulting in leaks, risk of loss of containment, and problems relating to structural integrity.
- Unplanned maintenance and repairs.
- A threat to human health (if chemicals leak).
- Increased risk of fires and explosions.
- Metal fragments can get into the pipework, compromising the quality of the transported product.
Flange inspection
It’s important to carry out regular visual inspections of all flanges, looking for any signs of rust (red-brown surfacing discolouration), and signs of what may look like mould growing and building, and surface pitting.
Some of the most common causes of flange corrosion include:
Galvanic corrosion – occurs from dissimilar metals, similar metals with anodic/cathodic sites, or from unintended sources of electricity. Without proper flange protection and gasket isolation, galvanic corrosion can lead to full failure of the mechanisms.
Crevice corrosion – corrosion occurs in the small spaces between the sealing surface and the gasket as an acidic environment builds due to a reduction in oxygen in the area. This acidic environment will corrode through metals, causing gaskets and joints to fail.
Localised corrosion – most apparent in pipelines carrying oil and gas, operating near seawater, corrosion here occurs at the flanges’ interior as the exterior remains uncorroded. Important note: localised corrosion can be incredibly dangerous due to the transportation of liquids at high temperatures, which, if failures occur, can lead to sour corrosion.
Note: Environmental and operating conditions will also be high dictators of the severity of corrosion, as well as the liquid being transported.
Flange corrosion protection
As well as corrosion-resistant materials, most flanges within pipe systems must also be fire safe and chemically compatible, and this is important to bear in mind.
Gaskets are the most common solution to prevent corrosion at the pipe flanges. Gaskets should therefore be well designed and installed, sealing the space between two adjoining pipe flanges comfortably.
Gaskets can also electronically isolate the connection between flanges, restricting direct contact between dissimilar pipe materials.
To prevent simple and galvanic corrosion in metal pipelines, electrical fluids can be passed through the pipeline in question, in order to equalise the electrical potential within the pipeline sites. This procedure will help to reduce the effects of corrosion as it also provides a coating to the piping system.
Flange insulation sets
Insulation sets can be used in above-ground pipe systems (with monolithic isolation joints found below the ground), and stop the electrical flow through the pipeline, protecting certain areas that have been identified.
The aim of flange insulation sets is to break the metallic path to stop the electrochemical reaction that can occur between dissimilar metals and offer high levels of flange protection.
Insulation sets consist of:
- Isolating gasket
- Isolating sleeve, and
- Washers.
Flange isolation sets help to improve efficiency and break up the electrochemical process and connectivity between adjoining pipes.
Ultimately, isolation sets ensure flanges remain free from corrosion-causing fluids, while also keeping them separate from direct contact with adjoining metal flanges.
Gaskets and seals
Helping to prevent flange corrosion, product loss, contamination, and, in severe cases, fire and explosions, at Specialist Sealing Products, we provide a wide range of high-quality and suitable gaskets and seals for use in various applications.
Providing sealing solutions for the most demanding industries, we design and manufacture gaskets and seals to the highest quality standards.
To find out more, contact us today. We’d be happy to help.
You may interested to read the next article: O-Ring Lubricants
