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.
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.