Why insulate flange?
Why insulate flange?
(OP)
Why is it important to insulate flanges at transitions between below grade and above grade interface? What does it do?
Also why is it important to weld bond wires to pipe? What is the advantage of making the pipe conduct?
Thanks!
Also why is it important to weld bond wires to pipe? What is the advantage of making the pipe conduct?
Thanks!





RE: Why insulate flange?
RE: Why insulate flange?
RE: Why insulate flange?
2nd question: Bond wires are typically provided between joints of metal pipe for cathodic protection purposes. A typical cathodic protection system either uses and impressed current on the pipe or sacrificial anodes. If you don't have a connection between the joints of pipe, you would have to provide a system for each individual joint.
RE: Why insulate flange?
Electrical insulation is for cathodic protection as coloeng states, typically where you have iron or steel potentially in contact with stainless steel.
RE: Why insulate flange?
RE: Why insulate flange?
RE: Why insulate flange?
CP design will be based, essentially, upon the buried portion of the pipe. The pipe may come above grade and then enter a plant with substantial buried metal and/or earthing system. Since, without insulation, there will be electrical continuity, the efficacy of the protection on the buried pipe could be reduced or rendered ineffective. NACE Standard RP0286 will give you good background.
Bonding, as well as being required to overcome breaks in conductivity along the pipeline, may also be required between the pipeline and any adjacent structures to prevent interference. Again, NACE Standard SP0169 will give you good background.
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdoweb/
RE: Why insulate flange?
This is a pretty common setup on gas pipelines.