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We are injecting Gaseous ammonia in crude column overhead line, also circulating the wash water in overhead line.
We are also injecting caustic in desalted crude. Corrosion is mostly due to desublimation of salt. Can someone recommend how we can avoid corrosion in overhead line?
 
Answers
25/05/2011 A: Sudhakara Babu Marpudi, Dangote Oil Refinery Company, m_sudhakarababu@yahoo.com
The piping bends are the low velocity zones in the overhead piping and they are more susceptible to corrosion. One can try insulating these bends and keep them hot so that the condensation is kept to minimum. Otherwise the corrosion can not be completely avoided.
18/05/2010 A: Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
Not really enough information supplied to tell. Some things to think about are how high your chlorides are and whether you can reduce them further through better desalting. Do you have enough wash water and is the injection system designed to effectively scrub the chlorides out of the vapor phase? Am I using the right corrosion control chemistry? As other responders have indicated, a filming amine can be useful. Also gaseous ammonia is normally not recommended for pH control - difficult to get rate right and the ability to raise the pH at the water dew point is more limited than most of the neutralizing amines offered by the chemical suppliers. There are also safety concerns with having gaseous ammonia at many sites. If you are going to use ammonia, aqueous ammonia is usually preferred. If you have a well designed water wash, the aqueous ammonia can go in with the wash water.
09/04/2010 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
1. Improve the desalter operation.
2. Use more water in the water wash.
3. Try filming amine in the overhead.
09/04/2010 A: keith bowers, B and B Consulting, kebowers47@gmail.com
The very first thing is to improve desalting performance to remove the salts.
Then consult with your additive supplier (Nalco, Betz, etc.) and learn what they can offer for your specific conditions. Usually a film-forming amine will be needed to prevent corrosion in the crude overhead line.
However, it is vital the cause of corrosion be clearly identified. The anti-corrosion treatments must be selected and designed to work properly in the specific environment where corrosion is taking place.
Many particulars and details are important. The efficiency of injection nozzle, location(s), and rate in relation to desalted crude characteristics are only some of the factors that must be evaluated.