Sulfidation corrosion (SC) is the result of naturally occurring sulfur compounds in crude oil. Today, it remains a significant cause of leaks leading to replacements, unplanned outages, and large property losses.

This form of corrosion can occur whenever sulfur compounds are present in a hydrocarbon stream and the temperature exceeds approximately 450°F. As discussed in API RP 939C (2), when exposed to sulfidation corrosion conditions, individual carbon-steel piping components with low silicon content (less than 0.10% Si) can corrode at an accelerated rate not readily detected even by multiple Corrosion Monitoring Locations (CMLs).

What does it mean for your facility?

Sulfidation Corrosion results in depletion of wall thickness in fittings, piping, heater tubes, and pressure vessels. Because of their thinner wall thickness and higher population density, most industry incidents occur in piping components. The majority of damage is general or uniform in nature and can be found over a relatively large surface area of a given component.

There are three main reasons that sulfidation corrosion can cause industry failures:
1. Lack of adequate UT Thickness and Positive Material Identification (PMI)
2. Piping systems that have a mixture of higher silicon and lower silicon containing steels
3. Process Creep – the gradual increase over time in hydrogen sulfide content of process streams introduced by changing feedstocks.
When those failures occur, it can cause major asset losses and unplanned downtime that can drastically effect your facility performance. Early detection matters to prevent these issues.

What can you do about it?

Inspections for SC can provide a practical guide to inspectors, maintenance, reliability, project, operations, and corrosion personnel on how to address it in petroleum refining operations.
Leveraging advanced technology in your inspection programs can help to more effectively identify sulfidation corrosion and prevent further issues.

The most effective inspection techniques to detect SC include:
1. Risk Based Inspection (RBI)
2. EMAT High Temperature Weld Detection
3. Ultrasonic Thickness Testing
4. Positive Material Identification (PMI)

To learn more, contact one of our specialists at for a complimentary consultation.

About ACTT
Advanced Corrosion Technologies and Training (ACTT) is the leading choice for corrosion detection and diagnosis for the petrochemical industry, where corrosion is a constant threat. To prevent failure, damage, and downtime, you need the most cutting-edge detection technology available, operated by experts in non-destructive corrosion testing. With the very latest advanced detection tools, and an experienced team of inspectors and operations centers close to you, ACTT is uniquely positioned to keep your business operating safely and reliably.

API Recommended Practice 939-C, “Guidelines for Avoiding Sulfidation (Sulfidic) Corrosion Failures in Oil Refineries”, First Edition, May 2009.