Dead leg corrosion Modification

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9 years 1 month ago - 9 years 1 month ago #8199 by Deepu
Dead leg corrosion Modification was created by Deepu
Hi All,

Let me explain the situation.
Condensate line from inlet separator has got dead leg corrosion in a plant. The reason for corrosion is due to low production and hence no flow and caused dead leg corrosion.
Modification suggested is to connect the condensate line to water line from inlet separator.
Also suggested that the modification is a shot fix due to the fact that if production increases we need to go back to separate condensate and water line which is the original design.

My suggestion is why can’t we use a higher schedule pipe (currently they are using 150NB Sch 40 A106 Pipe ) and change the old pipe spools with new one. Advantages are we are not changing the original design, we can use old iso’s same pipe supports,no need to change booster pump logic etc .Design life is only 5 years and almost 3 years finished.

As per piping point of view which is a better solution?
Also as many have been in this situation before , can anyone give what their approach would have been while facing problem like this .Thank you.
DV

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9 years 1 month ago - 9 years 1 month ago #6483 by Jop
Replied by Jop on topic Re: Dead leg corrosion Modification
Can you include a sketch?

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9 years 1 month ago - 9 years 1 month ago #6484 by Deepu
Replied by Deepu on topic Re: Dead leg corrosion Modification
Hi Jop,

Can I sent some info through email as I cannot attach.Thanks.

Deepu

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9 years 1 month ago - 9 years 1 month ago #6485 by Jop
Replied by Jop on topic Re: Dead leg corrosion Modification
Yes, you may send what you have via e-mail.

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9 years 1 month ago - 9 years 1 month ago #6487 by Jop
Replied by Jop on topic Re: Dead leg corrosion Modification
Deepu,
I have looked at your sketches and read your note explaining what you want to do and the options.
I have the following comments:
a). The P&ID does not identify the portion of the lines in question. So I can only guess.
b). The Piping Plans do not identify the portion of the lines in question. (Same comment)
c). Your option "A" (replace Sch 40 with Sch 80). If this modification is part of the Pump Suction line the heavier wall thickness will have an impact on the Stress analysis.
d). Your Option "B" (replace Carbon Steel with Stainless Steel). If this modification is part of the Pump Suction line the change in material (rate of expansion) will have an impact on the Stress analysis.
e). I do not believe there is a significant cost difference between Schedule 80 Carbon Steel and Sch 40S Stainless Steel,

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