Sulfidation Corrosion

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Sulfidation Corrosion (also known as sulfidic corrosion) is a result of naturally occurring sulfur compounds found in crude oil. In the absence of hydrogen, corrosion due to sulfur compounds in the crude is thought to occur at temperatures above 500°F (260 °C). Up to that temperature, corrosion rates due to sulfidation are relatively low, even for carbon steels, unless there is naphthenic acid present in the crude. High temperature sulfidation is one of the most well-known corrosion mechanisms in the oil refining industry because it can occur in multiple sections of the refinery.

Sulfidation corrosion results in the thinning of the pressure containment envelope, affecting components such as piping and pipe fittings, heater tubes, and pressure vessels. Most industry incidents have occurred in piping, due to lower nominal wall thicknesses compared to other equipment types. Sulfidation can be localized or general in nature for a given component; although the majority of cases exhibit general thinning. When the damage is general and thinning occurs over a large area, ruptures are possible and can lead to the potential release of large quantities of hydrocarbon streams.

Corrosive thinning of piping walls and equipment due to sulfidation depends on many factors, such as materials of construction, sulfur content of the oil, temperature, flow rate, and H2 concentration, making it hard to predict accurately. However, one predictor of higher sulfidation rates is low silicon content in carbon steel components.

Inspection methods for finding low silicon components vary, and programs differ from stripping all insulation, to the use of radiographic methods or long range guided wave UT methods to find all welds and selectively stripping insulation. This allows access to the piping on either side of the weld, as well as the weld itself.

Of course, rather than stripping insulation, there are more practical ways to perform baseline thickness checks. For example, one could use an X-ray imager to find welds and then cut a cookie in the insulation to check the thickness of each piping segment. Once the cookie has been cut, thickness checks can be done and positive material identification (PMI) could be performed. Pulsed eddy current (PEC) is also useful NDE technique for finding thin components without stripping insulation.

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Articles about Sulfidation Corrosion
July/August 2023 Inspectioneering Journal

Part 3 of this series focuses on practical damage mitigation and life cycle management techniques to avoid failures and corrosion in refinery pressure equipment.

May/June 2023 Inspectioneering Journal

This installment of Damage Control outlines the FFS methods available to analysts for evaluating wall loss such as sulfidation or high-temperature H2/H2S corrosion in pressure equipment

March/April 2023 Inspectioneering Journal

Comprehension of the sulfidation corrosion reaction and the behavior of different materials in H2-free and H2/H2S environments is imperative for oil refineries.

July/August 2021 Inspectioneering Journal

Recent advances in UT technology now allow for inspection and continuous monitoring of sulfidic corrosion to be undertaken while the components are on-stream, at temperature, with high-resolution thickness data.

Authors: Tim Stevenson
July/August 2019 Inspectioneering Journal

Gasification technology has emerged in oil and gas due to the high combustion energy of Syngas and less environmental concerns than flue gas. This article discusses proper inspection and corrosion monitoring techniques for gasification units.

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January/February 2017 Inspectioneering Journal

This article summarizes a comprehensive survey conducted by the Research & Development Center (R&DC) of Saudi Aramco to understand top corrosion damage mechanisms experienced by its operating onshore surface facilities.

September/October 2016 Inspectioneering Journal

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Equity Engineering Practices® (EEPs) are a collection of design and maintenance focused corporate standards that include >850 engineering standards, and >300 piping classes. Enhance your mechanical integrity programs, improve equipment...

March/April 2014 Inspectioneering Journal

High temperature sulfidation is probably the most well- known corrosion mechanism in the oil refining industry because it occurs in large sections of the refinery.


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March/April 2013 Inspectioneering Journal

Sulfidic corrosion of piping and equipment within the refining industry continues to be a significant cause of leaks and issues that can lead to early replacements, unplanned outages, and incidents potentially resulting in loss of property and...

September/October 2012 Inspectioneering Journal

On August 6, 2012, a piping failure occurred in the #4 Crude Unit at the Chevron U.S.A. Inc. refinery in Richmond, CA. Chevron U.S.A. would like to share some potentially significant preliminary information regarding the incident.

July/August 2004 Inspectioneering Journal

High temperature sulfidation is probably the most common high temperature corrosion nemesis in the refining industry, since there are very few “sweet” refineries still in operation. Sulfidation corrosion typically is of concern in sour oil...

Authors: John Reynolds
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