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Naphthenic Acid Corrosion And Sulfidic Corrosion In Crude Oil Fractions

In the petroleum industry, much greater attention has been focused on more highly sour and acidic oil resources due to the gradual depletion of conventional sweet oil resources. In addition, reducing crude oil costs have forced to look for opportunity (alternate) crudes, usually low-quality corrosive crude oils with high concentrations of naphthenic acids and sulfur compounds.1 The main constituents in the crude that cause corrosion are sulfur compounds, organic and inorganic chlorides, salt water, organic and inorganic acids. Processing of these highly acidic and sulfur-containing crudes at high temperatures in refineries has promoted significant corrosion problem in hot oil distillation units and associated piping systems.

Product Number: 51322-17533-SG
Author: Yuhchae Yoon, Hui Li, Kwei Meng Yap
Publication Date: 2022
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$20.00
$20.00

Crude Corrosivity issues manifest themselves at locations where fluid flow rates and velocities are relatively high in atmospheric distillation units, vacuum distillation units, transfer lines, valves, baffles, heat exchangers, and side cut piping in refinery systems. The heavy vacuum gas oil fraction of the vacuum distillation plant is the crude fraction which usually has the highest total acid number (TAN) due to high concentration of naphthenic acids close to their boiling points. This mechanism of non-aqueous corrosion in the presence of crude oil or oil fractions with high quantities of organic acids and sulfur compounds is termed as high-temperature naphthenic acid and sulfidic corrosion.

This paper will describe naphthenic acid corrosion behavior and corrosion rates of multiple alloys (C1018 carbon steel, A182-F5 5Cr-0.5Mo low alloy steel, A182-F9 9Cr-1Mo alloy steel, AISI 410 stainless steel, and AISI 304L stainless steel) stemming from a comprehensive Joint Industry Program (JIP) conducted to quantify influence of crude oil chemistry on naphthenic acid corrosion, contributions of reactive sulfur chemistry to protectiveness and FeS scale formation, and the ability to resist naphthenic acid corrosion utilizing beneficial sulfur speciation within the context of operational parameters of temperature and wall shear stress.

Crude Corrosivity issues manifest themselves at locations where fluid flow rates and velocities are relatively high in atmospheric distillation units, vacuum distillation units, transfer lines, valves, baffles, heat exchangers, and side cut piping in refinery systems. The heavy vacuum gas oil fraction of the vacuum distillation plant is the crude fraction which usually has the highest total acid number (TAN) due to high concentration of naphthenic acids close to their boiling points. This mechanism of non-aqueous corrosion in the presence of crude oil or oil fractions with high quantities of organic acids and sulfur compounds is termed as high-temperature naphthenic acid and sulfidic corrosion.

This paper will describe naphthenic acid corrosion behavior and corrosion rates of multiple alloys (C1018 carbon steel, A182-F5 5Cr-0.5Mo low alloy steel, A182-F9 9Cr-1Mo alloy steel, AISI 410 stainless steel, and AISI 304L stainless steel) stemming from a comprehensive Joint Industry Program (JIP) conducted to quantify influence of crude oil chemistry on naphthenic acid corrosion, contributions of reactive sulfur chemistry to protectiveness and FeS scale formation, and the ability to resist naphthenic acid corrosion utilizing beneficial sulfur speciation within the context of operational parameters of temperature and wall shear stress.

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A Review of Naphthenic Acid Corrosion and Sulfidic Corrosion in Crude Oil Refining Applications

Product Number: 51319-13443-SG
Author: Yuhchae Yoon
Publication Date: 2019
$20.00

Corrosion problems related to crude refining became a dominant concern as crude oil refining expanded to serve global energy demands with economic costs and benefits in the petroleum industry and more so with the availability of ‘opportunity crudes’. Reducing oil production costs have continuously forced refineries to look for so-called “opportunity” or “alternate” crudes which are usually lower quality higher corrosivity crude oils with higher levels of naphthenic acids and sulfur compounds. Processing of these high acid high sulfur crudes has engendered significant corrosion concerns in hot oil distillation units and associated piping systems.Mitigating ‘opportunity crude’ corrosivity involves several strategies including improvement of the refining process of blending crudes injection of inhibitors de-acidification utilization of better materials with higher corrosion resistance control of flow velocity and associated wall shear stress produced by the flow media and finally optimization of in-service inspection and monitoring in oil refineries. This paper will review based on the experience of the authors in developing extensive naphthenic acid corrosivity data from a comprehensive Joint Industry Program (JIP) the influence of crude oil chemistry on naphthenic acid corrosion contributions of reactive sulfur chemistry to protectiveness and FeS scale formation and the ability to resist naphthenic acid corrosion utilizing beneficial sulfur speciation as well as acid molecular weight molecular structure molecular boiling point as well as operational parameters of temperature shear stress and alloy metallurgy.Key words: Naphthenic Acid Corrosion Sulfidic Corrosion Corrosion Prediction Opportunity crude processing