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Anonymous Poster #1

Sacrificial Anode Required by Client for Pipes Coated With Phenolic Epoxy

01/08/2012 6:46 AM

We would really have to know that the requirements of sacrificial anode for phenolic epoxy painted pipes and what is basic criteria to provide sacrificial anode in buried condition?

Operating temperature range of our line pipe is 43-170 degree C and product Intertherm 228 recommended by manufacturer (International Paint) which can withstand up to 230 degree C in buried condition. Our line pipe suppose to be backfilled by sands in trenches. Please request to all to give their feedback on this topic.

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#1

Re: Sacrificial Anode Required by Client for Pipes Coated With Phenolic Epoxy

01/08/2012 8:54 AM

"basic criteria to provide sacrificial anode in buried condition?"

Find a substance that will corrode//rust/decompose more readily than the primary material of construction. Zinc seems to be popular. The polymer coating is not important.

You should hire an engineer with some corrosion experience.

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#2
In reply to #1

Re: Sacrificial Anode Required by Client for Pipes Coated With Phenolic Epoxy

01/08/2012 9:16 AM

Thanks Mr. lyn to know about the criteria limited to buried only,

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#3
In reply to #2

Re: Sacrificial Anode Required by Client for Pipes Coated With Phenolic Epoxy

01/08/2012 9:22 AM
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#4
In reply to #3

Re: Sacrificial Anode Required by Client for Pipes Coated With Phenolic Epoxy

01/08/2012 10:00 AM

Thanks a lot

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#5

Re: Sacrificial Anode Required by Client for Pipes Coated With Phenolic Epoxy

01/08/2012 3:54 PM

Why do you need sacrificial anode at all?

Coated pipes, properly protected with epoxy, fitted with appropriate jointing techniques and fasteners have high lifetime reliability.

Plastic wrapping (or alternatively DENSO wrapping) provide high reliability systems for burried pipes by stopping Oxygen transfer and so corrosion stops once the enclosed Oxygen is depleted. This system is used in water/sewer industry, protection for underwater components of wharves and bridges in fresh and seawater.

Ask the pipe/fitting supplier for their recommended practices and don't take shortcuts.

If you already have epoxy coating, then the joints are where the protection is required, unless the epoxy has been damaged.

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#6
In reply to #5

Re: Sacrificial Anode Required by Client for Pipes Coated With Phenolic Epoxy

01/09/2012 2:05 AM

Thanks but those pipes being used for close drain lines have already been painted with above said paint, This relevant pipes painted in workshop and shifted to site after 100% holiday test by sponge method except the area of weld girth and identification mark of pipes and now responsibility of painting & testing for balance area (weld girth+ identification mark) goes to site people,

As i am a representative of contractor and installation of sacrificial anode was not decided from contractor but client proposes to install because of condition is buried

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#7

Re: Sacrificial Anode Required by Client for Pipes Coated With Phenolic Epoxy

01/09/2012 3:58 AM

Why anonymous ?

Join Us.

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#8
In reply to #7

Re: Sacrificial Anode Required by Client for Pipes Coated With Phenolic Epoxy

01/09/2012 4:03 AM

of course and thanks

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#9

Re: Sacrificial Anode Required by Client for Pipes Coated With Phenolic Epoxy

01/09/2012 8:11 AM

The starting point just has to be: what's in the pipe, its temperature and pressure?

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#10
In reply to #9

Re: Sacrificial Anode Required by Client for Pipes Coated With Phenolic Epoxy

01/09/2012 8:47 AM
  • Service : Hydrocarbon,
  • Operating Pressure: 0.8barg,
  • Operating temperature: 43 deg.C and some line 170 deg.C

(Painted pipes going to use for hydrocarbon drain which has to be connected to sump)

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#11

Re: Sacrificial Anode Required by Client for Pipes Coated With Phenolic Epoxy

01/09/2012 9:20 AM

(with) respect given to Post9, the importance of the information given (Post10) lies primarily in the fact that lines carrying gas, oil, and hazardous liquids fall under the jurisdiction of different Codes than lines carrying water (for example).

In the U.S. (and many other countries), "API" lines must (in-addition-to protective coatings) maintain cathodic potentials ... often referred-to as pipe-to-soil potentials ... of -850mV with respect to a Cu/CuSO4 reference cell.

Information in books of the sort referenced above should be a MANDATORY starting place for you. This 'task' is not the sort of easy / cut-and-dried scenario that many persons would like to believe (and some would even suggest!). Peabody's Guide (see "References" HERE) has been one of the 'defacto_standards' for many years, to those involved with NACE (National Association of Corrosion Engineers International).

Step one is to determine the electrical characteristices of the line and to perform a Current Requirement Survey (to know how much current will be required in order to achieve/deliver the desired potential).

NO coating system is ever going to be totally and completely holiday free following installation. CP will afford protection to THOSE areas (it achieves *nothing* where the coating remains intact).

Sand typically exhibits an extraordinarily high resistivity, and thus, does not lend itself (as an electrolyte environment) to adequate protection via sacrificial anodes, as opposed to impressed current systems. That is, of course, unless the sand lies in a thoroughly soaked riverbed or swamp. MUCH more needs to be taken into consideration, before you dive into this project of providing cathodic protection.

Where is the line, and what systems are employed on similar lines in the area...?

Wishing you success ~

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#12
In reply to #11

Re: Sacrificial Anode Required by Client for Pipes Coated With Phenolic Epoxy

01/10/2012 1:24 AM

Thanks to all, this line is in saudi with saudi aramco total refining project and I have already been suggested to my head of department to install sacrificial anode after getting reply of Mr.lyn

Thanks again

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#13
In reply to #12

Re: Sacrificial Anode Required by Client for Pipes Coated With Phenolic Epoxy

01/10/2012 8:19 AM

Lyn's *best* advice to you was in his 'Post#1'... "You should hire an engineer with some corrosion experience."

Sacrificial anodes are unlikely to work at all in the arid environment.

Before spending 'dime number one' going any further, you ought to sign-up (free) for the Corrosion Forum (ListServer) at the NACE website: HERE

Ask the experts (of whom there are NUMEROUS from your area participating) just what will work best. You are guaranteed to get the most-experienced advice from the people who work in this field daily.....and share with each other, as well as 'newcomers'.

Wishing you the best ~

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#14
In reply to #13

Re: Sacrificial Anode Required by Client for Pipes Coated With Phenolic Epoxy

01/10/2012 10:17 PM

If the customer wants it and is willing to pay for it then oblige them.

Make sure you include the cost of a corrosion mitigation specialist's time.

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#15
In reply to #13

Re: Sacrificial Anode Required by Client for Pipes Coated With Phenolic Epoxy

01/11/2012 2:31 AM

Thank you very much Mr.Ndt-tom to help me to join Nace forum as well as give us precious time for subject matter

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Adeel Ahmad (7); Just an Engineer (1); lyn (2); ndt-tom (2); PWSlack (1); sanjaykangralkar (1); Wal (1)

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