Hello Richard. I've been working to revive an oil pipeline that has been dormant for about a decade. Cathodic corrosion was identified as a primary reason for the rupture that caused this prolonged period of inactivity. I have been responsible for installing the instrumentation and electrical at various new shut off valves along the pipeline. These valves are driven by compressed nitrogen, so there is alot of stainless tubing installed that would have been a connection to ground at each location had I not mentioned the cathodic protection. It wasn't too difficult to order dielectric unions to isolate the pipeline valves from the grounding stainless steel tubing. They are rated up to 5000 PSI if I remember correctly.
However, what was impossible to find were dielectric unions for listed for electrical hookups, let alone any that are rated for classified locations. We were ultimately forced to use galvanized plumbing dielectric unions for the conduit and flex connections to instrumentation on the pipeline.
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Jared Foster
Industrial Controls Group
Bakersfield CA
(661) 852-8159
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Original Message:
Sent: 02-01-2023 09:45 AM
From: Richard Flowers
Subject: Protecting Sensing lines
This month's lessons learned/ topic discussion is Sensing lines for Scada (Supervisory control and data acquisition). The first thing is even though the lines are normally stainless steel they must be cathodically protected if a portion of the sensing line is under ground. It is really important that the correct insulators are used for the isolation, they have to have the right pressure and electrical rating, if the insulator keeps failing due to lightning strikes, a SSD might be needed. A lot of the lines are directly connected to eletrical equipment, for the SCADA so a SSD might be needed for that application. Because the Sensing lines are stainless my company normally does not paint them, however atmospheric surveys should be done on the lines.
Hopefully this post can prevent some future headache or fines, if anyone has anything related to this post, I would love to hear it.
Thank you
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Richard Flowers
Atlanta Gas and Light
Sandy Springs GA
+17064249197
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