Monel

[Milutin]

Is it allowed use monel material for light gas oil draw try in crude unit fractionator? Try temperature is about 270C.

 

[25362]

Against what type of corrosion are you trying to protect the tray ?

 

[Milutin]

Local vednor, by mistake, made part of try from monel, any problems because of that?
Rest of try is some kind of SS.

 

[EdStainless]

I presume that he used Monel 400. You need to test and find out. It should be OK. Similar strength to 304L. Good corrosion resistance.
Maybe you should make a maintance issue of inspecting it more often to make sure that it is fine.

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[25362]

As far as I can recall monel is OK against naphthenic acid- and HCl- promoted corrosion. Chrome-containing stainless steels usually used on toppers should be adequate protection against sulfidic corrosion above 260^oC but aren't better than C-S on the naphthenic acidity issue.

I have heard that 316 SS, and better even, 317 SS (with at least 3.5% Moly.), are used to stand naphthenic acid corrosion, which appear to be intensified by turbulence. Naphthenic acidity may corrode at temperatures above the 230^oC level depending on the TAN value of the particular cut. Protection against this type of corrosion is frequently obtained by blending crudes to reduce the crude TAN values to around 0.5 mg KOH/g.