Mike Aughenbaugh, associate target market manager at Swagelok Company (Solon, Ohio, USA), is focused on the development of fluid handling solutions for the oil, gas, chemical, and refining markets.
In a sponsored episode of the Materials Performance (MP) Interview Series, Aughenbaugh explains many of the differences between pitting corrosion and crevice corrosion, as well as strategies to remediate corrosion, prevent corrosion, and educate system operators about what to watch for.
The complete podcast is available for listening below, with this summary collected with assistance from transcription service Otter.ai.
Episode Summary
In the episode, Aughenbaugh discusses corrosion in oil, gas, and chemical systems, highlighting an estimated $1.3 billion annual cost due to pitting and crevice corrosion.
He explains that pitting corrosion, common in seawater environments, is more destructive and widespread. Meanwhile, crevice corrosion—often localized under clamps and gaskets—can be more costly. Key factors include temperature, moisture, and electrolytes.
Augenbaugh emphasizes the importance of material selection, such as exotic alloys, and preventive measures like proper system design and operator training. He also notes the role of critical pitting and crevice temperatures in corrosion management.
Understanding Corrosion and Its Causes
As Aughenbaugh explains, everything corrodes over time. However, the speed and impact of corrosion can vary. moisture, oxygen, electrolytes, temperatures, acids, bases, mechanical stresses, and galvanic reactions are key factors.
Outdoor environments, especially those submerged in salt water or salt spray, are particularly corrosive—and especially at higher temperatures.
When asked about the prevalence of corrosion in oil and gas systems, Aughenbaugh says offshore environments are most problematic. Both internal and external corrosion are major issues.
Corrosion in Oil and Gas Systems
From there, Aughenbaugh discusses several corrosion-related challenges in offshore environments, as well as the potential use of exotic alloys to resist corrosion.
Citing the NACE International IMPACT study, Aughenbaugh estimates the annual cost of corrosion to the industry at $1.3 billion. That figure is split into material, labor, and safety costs.
On an optimistic note, Aughenbaugh shared an example of a downstream application where a material mix-up in a hydrofluoric (HF) acid unit was identified before a catastrophic failure. This highlights the importance of appropriate material selection.
The Initiation of Corrosion
Aughenbaugh explains that corrosion can form when a protective chromium oxide layer on metals is depleted. Subsequently, the material’s composition affects its corrosion resistance.
He then describes the microscopic topography of metals and how corrosive environments attack weak points, which further plays into the importance of material selection.
DuBose, who hosts the episode, directs listeners to Swagelok’s blog page for more resources on pitting and crevice corrosion. In response, Aughenbaugh reminds the audience that pitting corrosion is uniform across metal surfaces and typically forms under seawater environments, while crevice corrosion is often localized under clamps, gaskets, or hidden areas.
Common Alloys and Corrosion Susceptibility
When asked about common alloys in offshore environments and their susceptibility to corrosion, Aughenbaugh notes that offshore environments often require exotic alloys due to harsh conditions. On the other hand, downstream applications may use standard stainless steel (SS).
Aughenbaugh says one trend in downstream applications is updating specifications to lower thresholds for exotic alloy standards.
When asked about the suitability of Type 316L SS, Aughenbaugh confirms its effectiveness before emphasizing the importance of metallurgy in material selection.
Critical Pitting and Crevice Temperatures
DuBose asks about the importance of understanding critical pitting temperature (CPT) and critical crevice temperature (CCT) in addressing corrosion concerns.
Aughenbaugh explains that increased temperatures accelerate corrosion rates, and CPT and CCT are measured by exposing alloys to simulated environments to determine the point of corrosion formation. He then provides examples of CPT and CCT for 316L tubing, highlighting the differences between the two.
Aughenbaugh advises consulting site metallurgists or corrosion engineers to find the right alloy balance for cost and effectiveness.
Remediation and Prevention of Corrosion
DuBose inquires about remediation strategies for corrosion in systems, and Aughenbaugh emphasizes the importance of preventive measures and proper installation practices.
Aughenbaugh suggests using jacketed tubing with plastic jackets to prevent salt spray and galvanic corrosion, but he notes the need for proper sealing to prevent moisture ingress.
Aughenbaugh also discusses the importance of a total system layout, as well as the use of standard SS fittings with exotic alloy tubing to reduce costs.
When asked about available tools and resources to better educate system operators, Aughenbaugh recommends empowering operators to identify and document corrosion areas. They can also reach out to facility corrosion engineers or vendors for additional support.
More information is available at Swagelok’s web site or by listening to the complete interview.
Sources: Swagelok, www.swagelok.com; MP Podcasts, www.materialsperformance.com/podcasts.