Corrosion is constantly attempting to degrade the performance of metal pipelines. The corrosion can be from dissimilar metals (galvanic corrosion), stray current corrosion from unintended sources of electricity, simple corrosion of similar metals (with varying anodic/cathodic sites), microbial induced corrosion and there are lesser-known types of corrosion.
Cathodic Protection Systems
To prevent simple corrosion and galvanic corrosion, owners of metal pipelines will often send an electrical field through the pipeline equalizing the electrical potential for all sites (this is commonly referred to as a cathodic protection system) that dramatically reduces the effects of corrosion. Owners will also coat the metal pipelines to reduce the cost of electricity needed to protect the pipeline.
The Role of Isolation within CP Systems
To further reduce the cost of electricity to protect the pipeline and to keep the electrical field to an effective level, isolation is often used in the form of flange isolation kits or monolithic isolation joints. Both products accomplish the same task, but flange isolation kits (FIKs) are predominately found in above ground installations while monolithic isolation joints (MIJs) are commonly found below ground. The terminology can change a bit regionally, but names like flange insulating kits, iso-kits, electrical isolation gaskets are often used to describe flange isolation kits and iso-joint, iso-block, monobloc, monoblock or insulating joint are all synonymous with monolithic isolation joints. Both FIKs and MIJs will stop the electrical flow through the pipeline and serve to keep the electricity in the areas that the pipeline owner wanted to protect. FIKs and MIJs break the metallic path in the pipeline and optimize the protection of the pipeline. Because they break the metallic path, they also stop stray current up to significant voltages. Breaking the metallic path as a function of an FIK or MIJ is very important because it will stop the electrochemical reaction between dissimilar metals. Pipelines will typically have valves, compressors, pumps, meters, pig launchers, etc. that are not made of the exact metallurgy as the pipeline itself. This difference in metallurgy brings with it differing potentials in the metals. With differing potentials and an electrolyte, the pipeline and the component are ripe to endure galvanic corrosion. By simply inserting a flange isolation kit (FIK), the metallic path between the component and the pipeline is eliminated and galvanic corrosion is then mitigated.
Microbial Induced Corrosion
When an FIK or MIJ is made to the pipe bore, this can dramatically reduce microbial induced corrosion (MIC) issues. Microbe colonies will build when there is an area to hold media such as a gap between flanges. If the FIK or MIJ is made to the pipe bore, the gap is eliminated and the potential for microbial colonies to grow is dramatically reduced.
There are adjacent benefits to using FIKs and MIJs in that by decreasing the amount of electricity needed to protect a pipeline, owners will likely see reduced issues with coating disbondment, and hydrogen induced corrosion. Both of which can be caused by higher levels of electrical flow through the pipeline.
Fire Safe Isolation Kits
There are many types of flange isolation kits and monolithic isolation joints on the market today. It is recommended that if the pipeline is carrying a flammable material that a fire safe flange isolation kit be used. If chemicals are added to the media to reduce microbial colonies from forming, to act as surfactants, to reduce iron sulfide build-up or for any other reason or if chemicals such as hydrogen sulfide are part of the media stream, it is important that the isolation kit is chemically compatible with the chemicals being used.
Role of Isolation Gasket on Emissions
Today, many companies are attempting to achieve greenhouse gas emission reduction goals. If the pipeline is part of that effort, it is recommended that glass reinforced epoxy (GRE) based isolation gaskets and phenolic isolation gaskets BE AVOIDED as these materials are permeable. It is also recommended that when an isolation product is used (either flange isolation kit or monolithic isolation joint), that a pipeline decoupler also be used to mitigate stray current or lightning effects that are beyond the capabilities of the isolation kit or joint.
A common flange isolation kit will consist of an isolating gasket, an isolating sleeve and isolating washers (preferably fully coated and encapsulated stainless steel washers).
Typical flange isolation kit:
Typical monolithic isolation joint:
Introduction
Emissions, often referred to as Greenhouse gases (GHG) have been identified as a contributing factor in climate change. Climate change is one of the worlds more pressing challenges.
*Approximately 1-3% of methane leakage is the result of leaks in equipment intentional pressure release practices, or accidental releases during normal transportation, storage, and distribution activities.
Emissions is defined as the production and discharge of something, especially gas or radiation. In this instance we are talking about the production of unwanted gases often referred to as Greenhouse gases (GHG) that have been identified as a contributing factor in climate change. Climate change is one of the world’s more pressing challenges. Manmade carbon gas emissions total over 29 GT(gigatons) annually. To meet a 2° target according to the Paris Agreement, 15 GT of CO2 must be eliminated.
Fugitive emissions (unintentional production and discharge) account for 5.2% of all Greenhouse Gas Emissions according to the World Resources Institute, 2017. Sealing products that are extremely tight sealing are necessary to assist in the reduction of Greenhouse Gas Emissions globally.
Table of Contents
What are Pipeline Emissions?
How do we Measure Emissions?
Methods for Measuring Emissions
Pipeline Greenhouse Gases
How are GHG (Greenhouse Gas) Emissions Measured?
Greenhouse Gas Emissions by Country 2017
What is the Cause of Emissions or Poor Sealability?
Importance of Installing a Flange Isolation Kit (FIK) Correctly
How can do you Improve Pipeline Emissions?
Leakage Rates of Isolation Gaskets Vs a Spiral Wound Gasket
What are the Current Emission Standards in NA and Globally?
Which Sections of Oil and Gas Processing are Under Requirements by the EPA to Adhere to Emissions Standards?
Basics of Sealing
Gasket Load on Insulation Gaskets
Installing an FIK Gasket
What are Pipeline Emissions?
Emissions are the constant loss of product from within a pipe through and/or around a sealing element. Emissions are directly correlated to the sealability of a gasket or sealing product. It has been stated that “all gaskets leak”, but what is acceptable and unacceptable? Many companies are creating mandates to reduce GreenHouse Gas Emissions (GHG Emissions) to reduce the footprint for greenhouse gases and the EPA has strict standards when it comes to emissions for the oil and gas process. The creation of these requirements can now make a gasket that was once acceptable for emissions no longer acceptable.
Emissions today may not have been emissions in the past. As sensing technology has gotten better and the world has become more environmentally conscious, stricter and stricter requirements have been put in place. Chemicals that are injurious to the environment are often labelled as VOCs and HAPs.
"Volatile organic compounds (VOC) means any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, which participates in atmospheric photochemical reactions. Source EPA.
HAPS are Hazardous Air Pollutants, also known as toxic air pollutants or air toxics, are those pollutants that are known or suspected to cause cancer or other serious health effects, such as reproductive effects or birth defects, or adverse environmental effects. EPA is working with state, local, and tribal governments to reduce air emissions of 187 toxic air pollutants to the environment.
Emissions can be measured in many different ways. Emissions measurement is the process of measuring the amount of pollutants, in a gaseous or particulate form, being emitted to the air from a specific source, such as an industrial process.
Measurements of emissions can be used to understand the relative importance of a given source compared to other sources and in developing emissions inventories.
Government or industry personnel use emissions measurements to assess the performance of control strategies. The gas stream can be measured before and after a pollution control device to determine how efficiently it captures pollutants. Emission measurements also are used to determine compliance with regulations limiting the amount of pollution that a source may emit.
Measurements can be taken over a short time period (e.g., hours), often referred to as a source test, or with methods that measure on a continuous basis, often called continuous emissions monitoring. Either way, it is important obtain data from samples that are representative of the emission stream using methods that are reliable.
There is something else that is an unwanted type of emission and it is called Greenhouse Gas Emissions. Greenhouse gases trap heat and make the planet warmer. Human activities are responsible for almost all of the increase in greenhouse gases in the atmosphere over the last 150 years.1 The largest source of greenhouse gas emissions from human activities in the United States is from burning fossil fuels for electricity, heat, and transportation.
How are GHG (Greenhouse Gas) Emissions Measured?
There are many methods such as FID, FTIR, NDIR, airplane LIDAR, optical gas imaging, Aerostat Aloft Platforms, Radial Plume Mapping and Eddy Covariance Methods.
In a global effort to become less reliant on fossil fuels and more reliant on clean energy, hydrogen is and has been used as an alternative fuel source. Hydrogen is the smallest known molecule, so sealing it is crucial especially since it has low ignition energy requirements and has high combustive energy properties. Tight emission control of this element can be achieved through the use of non-permeable gasketing solutions and proper installation practices.
What is the Cause - Emissions or Poor Sealability?
Through research, we have found that one of the items that is supposed to keep product within the piping systems can actually allow material to escape into the atmosphere...the isolation gasket or insulating gasket! Most isolation gaskets are produced of some time of Glass Reinforced Epoxy (GRE). The glass in the epoxy matrix is a straight rod (similar to a straw) and media (especially gases) can follow that straight path and escape into the atmosphere.
This is 300psig Nitrogen at ambient temperature. Similar examples have been witnessed with hydrocarbon gases. The thing to note here is that the example in the picture was in a test lab with ideal flange conditions and proper bolt load. With less than ideal flange conditions and improperly torqued bolts, the permeation and emissions can be much, much worse!
Importance of Installing a Flange Isolation Kit (FIK) Correctly
Another cause of emissions or poor sealability can be poor installation. Over 80% of gasket failures are due to improper installation practices or improper equipment conditions.
How do you Improve Pipeline Emissions?
One of the answers lies in two patented solution from GPT….The VCS-ID gasket and the EVOLUTION Isolating Gasket. The VCS-ID gasket is constructed of GRE and a 316SS core, but a PTFE inside diameter (ID) seal prevents any media from ever getting to the GRE. The PTFE immediately seals the pipe bore and is extremely chemically compatible.
The EVOLUTION gasket on the other hand eliminates GRE totally from the design as well as benefiting from the addition of the PTFE inside diameter (ID). Resulting in unparalleled sealing tightness performance, ideal for emission reduction in pipeline connections.
Emissions can worsen as flanges get larger due to flange rotation. The VCS-ID reduces this issue by instituting a dual seal design for isolation gaskets 6” NPS (nominal pipe size) and larger. The Secondary seal is in an outboard location.
Leakage Rates of Isolation Gaskets vs a Spiral Wound Gasket
Note: Testing Performed at ambient temperature/500psig He /5hrs / 7,500psi gasket stress VCS-ID™ was single design only
Another major improvement to emissions and sealing is to participate in GPT’s GFIT program, GPT Flange Isolation Training. This program certifies participants in the proper alignment of flanges, the correct method of evaluating flange faces, tried and true torquing techniques, inspection procedures and provides “hands on” elements for both installation and isolation gasket testing.
What are the Current Emission Standards in NA and Globally?
According to the clean air act, all new oil storage tanks that come into service after April 12, 2013, must have VOC controls within 60 days of service or by April 15, 2014 (whichever is later). Tanks that were in service as of April 12, 2013, must have VOC controls no later than April 15, 2015. Tanks subject to existing federal or state CAA permits are exempt if they emit less than 6 tons of VOC per year with controls. Owners/Operators have the option of either reducing the VOC emissions at a tank by 95% or meeting an alternative emissions limit if the owner or operator can make a demonstration that the tank emits less than 4 tons of VOC per year without controls.
Which Sections of Oil and Gas Processing are Under Requirements by the EPA to Adhere to Emissions Standards?
Have you ever installed an isolating kit in a pipeline, successfully tested for electrical isolation, but later failed isolation following a hydrotest?
What part does load play with emissions and sealabilty?
Proper compression of the gasket is extremely important, but can be usurped by poor flange conditions or installation practices. We recommend using an installation procedure like this and making sure that flanges are aligned.
Is there training that can be taking to improve sealability for our products?
There are two training programs that GPT offers. One is the GFIT (GPT Flange Installation Training) program and the other is a Level I, II and III training program that teaches more about product selection, design and use.
Are there pitfalls that I can avoid regarding emissions and sealability?
The common issue that we see is the use of homogeneous GRE products in gaseous applications and then concern when they initiate some type of leak detection. It is quite common for these types of products to permeate (especially under higher pressure), so for gaseous applications, we recommend the use of a PTFE ID sealed isolation product.
Can liquid permeate through my GRE gaskets?
Surprisingly, the answer is yes. With high pressure and time, the media can permeate through the GRE. Another reason we recommend a PTFE ID seal to prevent any media contact with the GRE.
Basics of Sealing
Sealing capability is typically reliant upon two seemingly simple factors: gasket permeability and gasket load. Gasket permeability can be deceiving because many gaseous mediums are invisible and unless a person can acoustically hear the leakage or see a colored gas emitting from the gasket, the gasket has often been deemed “sealing”. As technology and requirements have become more strict, we now know the above not to be true. A gasket can still be leaking if a person is unable to see or hear leakage. Many companies now use a soapy water mixture to place on the gasket surface and gases leaking through the gasket or around the gasket will be displayed as bubbles.
Also, many companies now use much more sophisticated methods to assess leakage. The companies will use infrared technology to see temperature changes in the air caused by leaking gases. Companies will also use gas analyzers, helicopters, unmanned aerial vehicles, solar powered sensors (SPods) and chromatographs as well as other means.
There are also methods used to estimate fugitive methane emissions in transmission pipelines.
Gasket Load on Insulation Gaskets
Gasket load can be as complex as emission monitoring. Gaskets typically have a psi (pounds per square inch) or a kPa (1 kPa is approximately the pressure exerted by a 10-g mass resting on a 1-cm2 area. 101.3 kPa = 1 atm.) minimum requirement and a maximum allowable limit (note the maximum can change if the gasket is subjected to exposure in a liquid). Let’s say a gasket has a minimum gasket load (or stress) of 3,000 psi or 20,684 kPa and a maximum gasket load (or stress) of 15,000 psi or 103,421 kPa. This means the gasket will start to effect an acceptable seal at the minimum stress and can begin to break down at the maximum stress.
A “good” load on this gasket might be around 10,000psi or 68,948 kPa. This allows for some bolt stress relaxation and gasket relaxation to occur before leakage or gasket failure. Now how does one achieve the proper gasket stress? The answer is in torquing the bolts to the proper level to achieve the required gasket stress. This is where it can begin to get “complex”. The proper gasket stress will depend on many variables (reused nuts/bolts, rusty nuts/bolts, calibrated torque wrench, aligned flanges, proper flange face RMS (root mean square) finish (should be concentric or spiral grooves), type of lubricant used (if any), type and number of washers used (should be two washers).
Even the orientation of the nuts can be a factor (printed side of the nut should face away from the washers). There are other factors that should be taken into account, but these are the primary factors. Much has been written on this subject and a good book to read is John Bickford’s book on “Gaskets and Gaskets Joints.'
Installing an FIK Gasket
Here is a video that will help with the installation of an isolated kit in a flange. Installing an isolation kit is different than installing a standard gasket in even the same flange.
Our Recommendation
EVOLUTION is a superior choice for controlling emissions of methane, ethane, carbon dioxide, carbon monoxide (greenhouse gases) and hydrogen as well as many other chemicals that need to be contained in piping systems.
Introduction
Corrosion is a natural process where refined materials react with their environment, and revert to a more chemically-stable form. Below we discuss some of the most common topics and questions surrounding corrosion.
Table of Contents
Basics of Corrosion
The Galvanic Series
Cathodic Protection Design
Pipeline Corrosion Protection with Isolation
What is External and Internal Corrosion?
What was the Impact of Pipeline Incidents?
Why do we put Pipes Below Grade? What Challenges Does it Present?
How does Electrical Isolation help Prevent Corrosion?
What Applications Require Electrical Isolation?
What are Common Causes for Isolation Failures?
Basics of Corrosion
Corrosion is a constant force in industries from Oil & Gas production, Maritime, to construction of highways, bridges, pipelines, & any underground systems. Corrosion is a natural process where refined materials react with their environment, and revert to a more chemically-stable form. The rate of corrosion is dependent on a number of environmental variables, but for corrosion to occur four basic elements are required (Anode, Cathode, Metallic Path, and Electrolyte).
In the fight against corrosion, integrity engineers focus on removing the presence of one or more of these basic elements. The first defense against corrosion is a coating system which helps to protect the asset from the surrounding electrolyte. Coatings are typically used as a barrier coating, protecting the substrate from contact with the Electrolyte. In addition to serving as a barrier, some coatings also use inhibitive, or sacrificial pigments, causing passivation, or a sacrificial anode to form at any Coating Holidays or defects.
Integrity engineers must also utilize cathodic protection (impressed or passive) to protect assets, as coatings can be damaged, which can amplify corrosion locally at the defect (Coating Holiday, cracking, etc.). Cathodic protection systems combat corrosion by converting all of the anodic (active) sites on the metal surface of an asset to cathodic (passive) sites by supplying electrical current (or free electrons) from an alternate source to equalize the potential on the surface of the metal structure (left).
The Galvanic Series
Materials are listed from most Noble (passive), to most electronegative (active) in the Galvanic series. In reference to the below graphic, Magnesium is the most active. When two metals are coupled, the more active will share electrons with the more noble material causing an oxidation reaction (rust) at the electronegative material, and a reduction reaction at the more electropositive (noble) material.
Cathodic Protection Design
CP does not eliminate corrosion, but actually transfers corrosion current from the protected structure (asset) to the cathodic protection anode. This is the case in Galvanic (Sacrificial) anode systems, and impressed current system.
A sacrificial anode system is easily installed, requires no external electricity, and minimal right-of-way cost. The limitations of sacrificial anodes are current output, require anodes to be replaced once an anode has been spent / consumed, and a higher cost per unit ampere than impressed current. Based on the above characteristics, galvanic systems are used in specific applications (offshore, within vessels, or in an area with many other metallic structures). Galvanic anodes are commonly used in combination with impressed current systems at problem/ repair areas, shorted casings, cathodic interference / stray current discharge points, areas influenced by electrical shielding, and locations with significant coating damage.
Impressed current systems are comprised of an external power source and anodes. The power source (rectifier) forces current to flow from the anode to the structure to through the electrolyte.
Pipeline Corrosion Protection with Isolation
Pipe and the metallic pipeline components are supplied coated (Valves, Fittings, etc.). Following welding, and inspection field applied epoxies are used to cover exposed weld bevels.
What is Pipeline Isolation?
In metallic pipelines, corrosion is the constant attempt by nature to reduce pipelines to their original oxide state. It is an electrochemical reaction that has four parts: anode, cathode, metallic path and electrolyte. Flange isolation and joint isolation are a means of preventing electrochemical reactions from occurring between two dissimilar metals by breaking the metallic path, or preventing the current in a cathodic protection (CP) from traveling beyond the area intended to be protected by the CP system. ;
In addition, Cathodic protection (CP) systems are used to supply extra electrons causing the asset to be a passive location or a cathode. In order to control what is protected by these electrons, isolation is used as the ‘bookends’ of a CP system. Isolation will allow you to protect specific assets, and eliminate any dissimilar metals connection. An example would be a pipeline coming into a compressor station, the role of the CP system is to protect the pipeline, but not the compressor station. Isolation would be used on either side of the compressor station to avoid the large metallic compressor station draining the CP current.
What is External Corrosion?
External corrosion occurs due to environmental conditions on the exterior surface of the steel pipe that can cause an electrochemical interaction between the exterior of the pipeline and the soil, air, or water surrounding it. Galvanic and atmospheric corrosion are common types of external corrosion.
What is Internal Corrosion?
Internal corrosion occurs due to a chemical attack on the interior surface of a steel pipe from the products transported in the pipe. This can be from either the commodity transported, or from other materials carried along with the commodity, such as water, hydrogen sulfide, and carbon dioxide.
Is Natural Gas Corrosive?
Natural Gas can mean gas containing methane, Ethane, H2S, water, and COS, and other components. Natural Gas will be corrosive because of the H2S and water. Commercial Natural Gas is treated, and it is no longer corrosive.
What is PHMSA?
PHMSA is a portion of the DOT. PHMSA is the Pipeline and Hazardous Materials Safety Administration. Est. 1970.
How Many Pipeline Failures are the Result of Corrosion?
Data shows that from 1998-2017 approximately 18% of pipeline incidents on average were caused by corrosion, learn more here.
What was the Impact of Pipeline Incidents?
Why do we Put Pipes Below Grade? What Challenges Does it Present?
While there are above ground pipelines, most notably the Trans-Alaska Pipeline System (TAPS). The significant majority of pipelines are buried. Pipelines are often located below grade due to permitting requirements in order to minimize the impact to the surrounding communities by concealing it from view. Pipelines will come above ground for pump stations, valves, and other equipment requiring access.
Locating pipelines below grade introduces the pipeline into constant contact with an Electrolyte, one of the four elements needed for a corrosion cell. The first line of defense is a Barrier Coating, which creates a barrier between the Electrolyte and the metallic structure.
How Does Electrical Isolation Help Prevent Corrosion?
Electrical Isolation in a pipeline system is achieved by installing Flange Isolation Kits (FIKs), or Monolithic Isolation Joints (MIJs) in line to separate equipment or pipeline segments. FIKs & MIJs utilize materials with resistance to electrical current in order to block the transfer of electrons, effectively eliminating the metallic path, one of the four elements needed for a corrosion cell.
What Applications Require Electrical Isolation?
Electrical Isolation is used to break up pipeline segments to optimize current output from rectifiers in Impressed current cathodic protection systems. It is advantageous to break up long pipeline runs with isolation to improve efficiency, and minimize the impact of maintenance or repair on the pipeline.
Electrical Isolation is also used to prevent interference or damage to electronics, which may be found in valves, sensors, compressor stations, and other equipment.
Electrical Isolation should also be used in the presence of any dissimilar metal connection to prevent a galvanic coupling.
What are Common Causes for Isolation Failures?
Failure of electrical isolation gasket, joint, or union can be caused by environmental factors, mechanical forces exerted on the pipeline system, or improper installation. The likelihood of failure due to environmental factors can be controlled by the materials used.
A variety of materials are used to provide electrical isolation within a pipeline systems. The different materials have different characteristics which impact their efficacy (Electrical Resistance, Water absorption, Dielectric Strength, Permeability, Temperature range, Chemical Resistance, Compressive strength).
Electrical resistance is a measure of how well a material resists electrical current.
Isolation materials which have a high water absorption will be impacted by humidity, rainwater, and snowmelt. The moisture within the isolation material will cause a significant reduction in the electrical resistance. In conditions with temperatures fluctuating from above to below freezing also have the potential for cracking of the isolation material.
Introduction
A seal assists in connecting systems or mechanisms together by preventing leakage, containing pressure or excluding contamination.
A flange Isolation(insulation) gasket used in conjunction with an isolation kit (washers & sleeves), does all these things, but also provides electrical isolation, reducing or mitigating the build up of corrosion.
Table of Contents
1. What is Pipeline Sealing?
2. Why do Pipeline Sealings Fail?
3. Changing Oil and Pipeline Gas Conditions
4. GRE Isolation Gasket Pitfalls
Why do Pipeline Seals Fail?
Over 80% of leakage or isolation issues are from poor installation.
Installation
The most common pitfalls for a good seal is installation. Over 80% of leakage or isolation issues are from poor installation although we see this potentially changing in the future due to the fact that oil and gas companies are becoming more concerned about greenhouse gas emissions. As levels are put in place as maximum leakage levels, gaskets that were once deemed acceptable from a sealing level would potentially be labelled as “leakers” requiring a selection of a new type of isolation gasket. This could be entirely independent of the method of installation.
Most likely it has to do with installation. Over 80% of failures are attributed to installation issues. The most common installation issue is not creating a large enough gap for the gasket to EASILY be inserted between the flanges. Flanges should be aligned prior to the insertion of the gasket. The second most common cause of failure is improper application of torque. Make sure to use the manufacturer’s recommended torque, to install in three even increments of 33%, 66% and 100% of the recommended torque. Also, be sure to use a “star” pattern when torquing. A few other quick checks would be to make sure you are not using a lubricant that contains metallic particles, make sure that your washers are not “reversed” the metal washer must be the washer contacting the nut and make sure the nut “flat” is toward the washer, not the nut side that has raised printing.
Changing Oil and Gas Pipeline Conditions
Pipeline conditions have been changing over the last 50 years. More and more aggressive chemicals are finding their way into the media stream (hydrogen sulfide, steam, carbon dioxide, carbon monoxide, etc.). Temperatures have risen, pressures have risen and we are seeing a trend towards larger diameter pipelines which can be much more difficult to properly install and seal.
As a world leader in the manufacture of isolation products coupled with a significant engineering team, GPT has discovered that the changes in our pipelines are affecting traditionally used isolation gaskets. The combination of higher temperatures and higher pressures can cause blowouts of GRE based materials that do not have a glass transition temperature high enough for the operating temperature. Chemical combinations of sour gas can chemically attack GRE. What can compound this issue is the propensity for GRE to all media to permeate into the body of the gasket. This can cause a loss of volume, mass and density of the GRE. This in turn, can reduce bolt load causing greater leakage and potential for blowout.
Changes in the workforce have not helped pipelines to become better sealing either. The 5 year average for pipeline incidents according to PHMSA data shows that there have been an average of 666 incidents for the 5 year period from 2014 through 2018, however the 5 year average from 1999-2003 was only 474 incidents. Some likely reasons are that millenials are changing jobs at a much greater rate than baby boomers. LinkedIn has studied 500 million users over a 20 year period and has found that a millennial will change jobs an average of four times their first 10 years out of school. This means that the likelihood of a pipefitter being a long term, highly trained individual is diminished. Since more than 80% of gasket failures occur due to poor installation, a lesser trained workforce will not benefit the situation.
GRE Isolation Gasket Pitfalls
Unfortunately, Glass Reinforced Epoxy (GRE) the material that most isolation gaskets are constructed of, has significant permeation (see photo to the right). This is a GRE gasket (G10 in this case) with 300psi Nitrogen gas. Snoop™ leak detector has been applied and it is evident that the nitrogen gas is easily passing through the gasket. Carbon monoxide and carbon dioxide would perform similarly as would ethane and methane.
Oddly enough, isolation gasket manufacturers for years knew that the gases permeated through the GRE, but attempted to develop ways to use the media to drive through the body of the gasket and push the seal against the flange creating a seal (often called a “self energizing seal” and sometimes called a “leak to seal” design).
Fortunately, GPT has developed a patented method for sealing the media before it ever gets to the GRE. The product is called VCS-ID and has a PTFE inside diameter (ID) seal (see image).
The PTFE ID seal is machined to lock into the GRE and the 316SS metal core so that it is unable to come.
When I put “Snoop” on my gasket in a flange, bubbles appear very quickly and easily. Can I put more load on the gasket and stop the leak?
Probably not if you are using a glass reinforced epoxy (GRE) gasket. It is much more difficult to compress a GRE gasket as compared to a fiber or PTFE gasket. GRE unfortunately is prone to “permeation” and what you will often be seeing is permeation through the gasket rather than leakage past the seal. The solution to this is VCS-ID or Evolution which has a PTFE seal that stops the media before it gets to the GRE.
What is the best sealing isolation gasket?
From our lab testing, the Evolution gasket is the best available isolation gasket for an extremely tight seal. Typical sealability values are in the range of 1x10-9 Pa.m3/s/mm helium in ambient temperature testing. Most other isolation gaskets are in the 1x10-4 range.
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