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We observed that our crude unit naphtha stabilizer column overhead water has become decolourized since few days. The colour is yellowish to brown. However, the main column overhead water is clear in colour as previously. Can anyone help me in identifying the possible causes for this? Some forming also has been observed while draining this water. Can overdosing of corrosion inhibitor (filming amine type) cause this issue?

Further info:
Thanks for valuable answers. The colour was observed while draining of the vessel boot. So, there is no much time to react with atmospheric oxygen. Is it any dissolved oxygen that react to give the colour? Also, I found some evidence of overdosing (almost double ) of the corrosion inhibitor for a short period of time. Once it was corrected the colour was improved. But, not sure whether it is due to that or due to anything else.
21/06/2017 A: Biju Kolodi Thekkeyil, KNPC, ktbijukrl@gmail.com
Overdozing of corrosion inhibitor may give slight colour and emulsion-like appearance for water. If the color remains the same for some time after sampling, this may be the reason. If you have a water cooler before your reflux drum, check for tube leak.
22/02/2017 A: RAMAKRISHNA DADI, HMEL, dadi2rama@gmail.com
There is a chance of some over dosing of corrosion inhibitor or any chance of corrosion and leak internal to flow the hydrocarbon fluid. Batter to check the water or liquid sample collect and send for petroleum or water lab to analysis of PH,IRON ,and any hydrocarbon related symptoms.
22/02/2017 A: Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
Sounds more like corrosion products or elemental S to me. Iron sulfide in water will convert to iron oxide if exposed to some oxygen, either in the process or during sampling, which can cause a brown or orange color. Oxygen can also lead to a claus reaction with H2S resulting in formation of elemental sulfur and cause a yellowish color to the water.