NaOH - Oil Refinery Corrosion and Materials Issues Forum

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Discussion Forums - The Hendrix Group

4/6/2006 9:00 AM

Joined: 1/1/0001

Posts: 0

NaOH

What could be the corosion effects of 15% NaOH injection on carbon steel piping and storage tanks used in hydrocarbon service? What could be the effect of any caustic crystallisation (?) on pump mechanical seals? Please give more details on caustic embritlement. Is it same as SCC

4/6/2006 9:00 AM

Joined: 1/1/0001

Posts: 0

RE: NaOH

Dear Babu, Carbon steel is considered quite sensitive to the caustic services and special considerations are given in the desing and Heat treatment of Carbon steel welds under caustic services. The two most important factors are 1. Caustic Concentration 2. Temperature You can get some additional information regarding the relation between the concentration versus temperature for the PWHT requirements on this web site. If the components are not PWHT and designed for caustic service then they are prone for caustic embrittlement. Caustic embrittelement are one of the kinds of SCC( environmental cracking) where the caustic/Carbon steel/high stressed parts combines to offer the cracking. For 15% caustic solution below 70 Deg C is not a problem, but any thing above 70 Deg C requires PWHT. You have not mentioned about the service also. In the Boiler Feed water if there is caustic contamination then another type of damage mechanism occurs which is called as caustic boiling. Regards, Shabbar Hussain Refinery Corrosion Engineer Qatar Petroleum Refinery Qatar

8/2/2006 9:00 AM

Joined: 1/1/0001

Posts: 0

RE: NaOH and other question

Dear sir, I have a problem with an NaOH injection system, after DA desalters. So, what is the problem: Is necessary to realize a good system for NaOH, so that, will be a good homogenization betwen crude oil and NaOH solution, to reduce the acidity. Is necessary to have a demountable system, refering at a little dropper, that is necessary to enter in the crude oil pipe ( at a middle level, for a good homogenization). The diameter of cude oil pipe is 12 inches, and the injection is necessary to have a smaller diameter ( 1/2 inches), for a correct report betwen crude oil and caustic solution. How we can realize a demountable system, for cleaning the dropper, so that the crude oil not exit outside? Thanks in advance, Daniel Chitu Junior Process Engineer

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