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SS316L pipes internal Oxidation or Corrosion , Cleaning

SS316L pipes internal Oxidation or Corrosion , Cleaning

SS316L pipes internal Oxidation or Corrosion , Cleaning

we have an issue on site with the SS316L pipe internal joints areas "Oxidation / Corrosion" marks, need and expertise advice how this can be handled to clear the marks any other solution w/o proceeding with circulation cleaning, reason being asked for all the pipes are installed on-board of vessel. please advice.

RE: SS316L pipes internal Oxidation or Corrosion , Cleaning

Passivate the piping with 5% Nitric Acid. Circulate for half an hour to an hour.

RE: SS316L pipes internal Oxidation or Corrosion , Cleaning

Dear URKumar,

What is the pipe size? How did you find out the oxidation / corrosion marks in the internal portion of the welded joints?


Kolkata, India

RE: SS316L pipes internal Oxidation or Corrosion , Cleaning

First you have to decide what it is you are doing and what you want for a result.
IF this is superficial then 5% nitric is perfect.
However if you have heat tint or other serious issues then you would have to actually pickle with Nitric/HF to remove it.
More background is needed.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy

RE: SS316L pipes internal Oxidation or Corrosion , Cleaning

Dear Dhurjati sen,

my apology for late response, as im on year end holiday,
regarding your query for the pipe size it is 8" line and ship owner notified the black strains inside of the welded joint. this could happen deep inside of other joints as well, so to understand more, how this can be cleaned without circulating method.. ( need an advice if any other possibilities to rectify this issue ),


RE: SS316L pipes internal Oxidation or Corrosion , Cleaning

Dear URKumar,

1. Ask the ship owner exactly how did he find out the black stains?

2. Carry out a boroscopic survey of a few weld joints at random from your side.

3. Find out what are the cleaning / circulation activities Operations would carry out before commissioning this piping.

Now you could reach a decision.


Kolkata, India

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