48.1 Introduction

The American Society of Civil Engineers (ASCEs) and the Association for Materials Protection and Performance (AMPP) (previously NACE) have repeatedly pointed out that the US infrastructure is in bad shape. The incremental progress made in 2021 has delayed the unthinkable; a de facto “failing grade.” However, in the post pandemic period, we await with interest the results of future surveys, in particular those regarding offshore pipelines and other critical assets. The subject matter is vast, and so the References [1–26] and the 11 items in the Bibliography are quite selective but open to future-focused expansion as new data and works are explored.

At the front end of the impending scenarios are the numerous susceptible facilities; critical components of which appear potentially on the verge of collapse. The impact of climate change, safety, the environment, and artificial general intelligence (AGI) are now all hotly debated. All these topics are highly interactive, and global cooperation, ROI, motivation, and monetization remain major barriers. Climate change is a global problem. Changing weather patterns, increased flooding, and extreme atmospheric conditions affect pipelines, power plants, and other infrastructure. In this chapter, key issues will be highlighted to identify risk-based corrosion integrity management strategies, methods, and techniques. There is much visible evidence of climate change around the world, from rising temperatures, increasing storm events, melting ice sheets, increased flooding, novel viruses as well as changes to soil, plant, bacteria, and animal behaviors.

Solutions can be formulated by increased frequency of inspection and by monitoring—the latter will probably be enforced through necessity as the public observes that climate change leads to loss of materials integrity and failure.

The background of this work is an expression of the literature, industry, and geopolitical reviews based on critical observations and analyses that evolved over the past several years and are often only best understood by the complex interactions between science, engineering, technology, and man-made conduct, as reflected by major (and minor) events. The main objective of this chapter is to help focus and apply practical corrosion lessons learned from the energy/marine oil and gas industries to the new challenges caused by the evolving hostile environments and climate change. Some governmental agencies, such as DOI/DOT-USA, PHMSA, and HSE-UK, have intervened with recommendations on prescription and goal setting for inspection/engineering to help ensure continued safe operation of critical assets, e.g., the PHMSA Mega Rule, Peer Review, and Third-Party Verification.

Productive engagement between industry, academia, and pertinent public authorities can help in maintaining inherently safer and longer asset life cycles, as well as provoking further arguments and constructive discussions within the not-for-profit engineering societies. This is important, as too often the revenue and monetization angle get pole position; and although such monetization is important, infrastructure degradation as impacted by climate change is independent of borders, geography, and country status.

48.2 ALARP Factor

The most important parameter is risk, and we may utilize an established criterion; the ALARP factor. Engineering risk is defined to be “as low as reasonably practical.” For infrastructure degradation, one must adjust typically to a corrosion ALARP, illustrated in Figure 48.1.

Meaningful knowledge management of both raw and structured data is vital for best results and interpretation. The development of Figure 48.2 was a direct result of considerable interaction between industry and academia and shows that corrosion is and will continue to be a major issue within industry. Integrity management of assets is up to 80% corrosion related, depending on the risk factor.

More recently, many subject matter experts (SMEs) in the field have opined that >90% of process safety issues are metallic, corrosion, or welding related. Critical engineering parameters, such as HP/HT/HV/Souring/Pollution, etc., are clearly climate enhanced. Education and skill set enhancement is one way forward, though unfortunately while well intentioned, such traction has been thus far limited, usually by lack of funding. However, with the recent developments in applied artificial intelligence (AI) and massive language models (MLMs), major players, such as the USA/Europe/Canada/UK/India, have seen the advantage of joint ventures to address the issues, e.g., the National Science Foundation (NSF). Furthermore, the obvious interest level of young people is a boon, and so not much persuasion is needed.

48.3 Natural or Manmade?

The issue of manmade climate change per se is a controversial subject. The mere fact that increased corrosion and degradation are observable as a result of climate change should be worthy of major concern. The increases in such degradation are notable, and the signs are self-evident, even if not properly quantified. In some cases, increased corrosion rates are due to increased HP/HT/HV phenomena related to deeper subsea reservoirs, now far exceeding 7000 ft. Bleeding the earth in this manner, while considered necessary for human energy sustenance, is also a form of direct environmental tampering. Natural changes per geological time frames are indirect accelerators, such as for intermittent volcanoes, earthquakes, tsunamis, glacier ice fractures, etc., leading to sea level rise and residual airborne “contamination.” There are many papers and publications on the subject of climate change, but few, if any, address the interaction between climate change and engineering materials corrosion and degradation. Appendices 48.A.1 and 48.B.1 were developed to identify important criteria, mechanisms, modes, KPIs, etc., in precis format as suggested solution avenues for the discerning reader. Likewise, the Bibliography and References are intended to provide insights and methodologies that may be gleaned from the existing literature.

48.3.1 Swiss Cheese Model

One useful way of assessing multifaceted failures is via the famous Swiss Cheese model, interpreted for corrosion activity and illustrated in Figure 48.3. Irrespective of the arguments “for or against” climate change, increased corrosion activity is observed, perhaps also due to most infrastructure now being in its fourth quartile of design life.

Moreover, general increases in population, population distribution, and population densities lead to the side effects of greater consumption and thus waste, all-natural purveyors of greater asset degradation and corrosion. Hence, the battle against corrosion is an unavoidable factor in the climate debate. Apart from humanity and population growth, we now witness greater impacts from the animal and plant kingdoms, e.g., new strains of more resistant bacteria, new flu strains, greater preponderance of locusts, and dangers of some species facing extinction. Such matters (and more) are load demanding on the existing infrastructure and present new challenges for new designs. Improved corrosion management strategies, methodologies, and techniques are required.

Predicting increased infrastructure corrosion and material degradation as a result of climate change is not a controversial position—most, if not all, engineering alloys and nonmetallics can be expected to suffer more rapid deterioration and unexpected failures as the climate continues to change. This increased degradation should be manageable via effective C&IM plans, but unusual and unexpected corrosion phenomena can occur. It is likely that infrastructure assets will fail with increasing frequency and with root causes pointing to hidden corrosion, often after the event. Part of the problem is that SME conclaves have tended to opine outside their level of expertise, and this weakness can be addressed by effective peer review.

There are many case history examples to illustrate the relevance of climate change. It is widely recognized, for example, that atmospheric corrosion will accelerate as environments become more aggressive.

48.4 Engineering Steel and Infrastructure

Corrosion control, corrosion protection, CRAs, coatings, cathodic protection (CP), microbially influenced corrosion (MIC), corrosion under insulation (CUI), and accelerated pitting/crevice corrosion, etc., are all highly stimulated under conditions of climate change. It is widely accepted that controlling degradation at initiation (especially in crevices, cracks, and similar sites) is the key to effective corrosion and integrity management (Figure 48.4).

Referring to Figure 48.4, when localized corrosion is initiated (I), it is not always measurable but is reasonably predictable by: Analysis, forensic methods, analogy, under the umbrella of ALARP. The diagram may help optimize strategy regarding whether to: (1) Run to Failure, (2) Run to Degrade—to corrosion allowance (CA), or (3) Run to MAWT. There are geographical differences as local climate, soil, seawater, and related pollution distributions evolve.

48.5 Reasons for Optimism

Because necessity is the mother of invention, major advances within the area of infrastructure integrity and corrosion management will be established, especially considering the crossover into safety management (HSSEQ$) and AI. High-priority items for pipelines that are likely to be stimulated by climate change are:

1. CUI, MIC, FILC, HP/HT/HV, UDC/CUD, These are considered priority—In reality, there are now well over 20 discrete localized corrosion mechanisms identifiable.
   
2. Soil side corrosion and loss of CP—with encouraging signs of better standards and practices. Though warning signs exist per AC/DC interference and the actions of complexing MIC.
   
3. Coatings break down, Incl. previously lower-risk reverse polarities of certain alloys,
   
4. Accelerated corrosion under storage/preservation/mothballing.
   
5. Enhanced role of green Inhibitors, plastics (FRP and CFCs).
   
6. Detection, measurement, and management of pipeline displacement resulting from slope instability and ground movement.
   
7. Needs based or regulation enforced better inspection and monitoring regimes.

48.6 Discussion and Closing Remarks

The climate change argument may be a rhetorical draw, but it would not go away! Nevertheless, in general, when engineers, scientists, technologists, and Internet of Things (IoTs) people collaborate, recent history shows that lessons are learned, solutions are found and challenges are met! Albeit slow, better corrosion/flow regime predictive correlations for pipes and structures are one important recognition, as are CP/coatings and inhibitor advances. Either way, the world’s public square will provide the ultimate tipping point for meaningful action or inaction. Supporting case histories and experiential trends, including to be fair, societal over-reactions, can be instrumental in either catalyzing, accelerating, or slowing down is helpful. The dominant unresolved integrity issues, such as extreme stress analyses, turbulence identification and prediction, fouling/scaling assessment, localized hot spot corrosion, and materials selection in the climate change era, have remained but are now addressed with greater urgency.

Although there is little short-term monetization of safety, and virtually no rewards for prevention, both are vastly superior to belated cure! The tools of the trade have been established and do need “re-honing.” The climate change problem is now nearly continuous; hence, the solutions mantra must remain to be: try, try, and try again. Although global regulations almost certainly must play a role, especially through engineering lessons learned, individual country statutes will need to suffice in the interim. Two empowering tools will be the resurgence of appropriate independent peer reviews, akin to third-party verification, and plans for more frequent risk-based inspection. Both are (to the limits of ALARP) on the verge of implementation in the offshore and pipeline industries in North America. Much of this is an ongoing dialogue and work in progress within and beyond the bounds of the References given.

As with other complex localized corrosion/degradation issues, the key to “fit-for-purpose” resolution is a good multidisciplined combination of rigorous theory, effective lab testing, and representative field testing. The role of motivated young, trained minds here is invaluable, as has already been well observed, albeit without the deserved attention. This should become self-apparent as we delve further into new materials, climate change, and greener chemicals, all intertwined with the positive aspects of machine learning (ML), AI/Chat GPT, etc. Education is paramount, especially regarding skill set evolution. Some initiatives, including proposed additions to curricula, are being implemented.

Solution approaches are not for the faint-hearted, and a concerted effort across nations to deploy the proactive skills of highly experienced SMEs (civil, structural/mechanical, metallurgical, nonmetallic, corrosion, etc.) will be needed if we are to succeed. Often this is best exhibited with the amalgamation of SMEs with the budding young entrepreneurs. This diversity of approach is a strong proponent of better logic and the minimization of dangerous group think although sometimes solutions may be temporary to essentially “buy time” until more permanent solutions are found. Since engineering knowledge and applications are being stretched to the extremes of the climate changes envisaged, peer review, and third-party verification are essential.

Caveat and Acknowledgments

This chapter is based on strong continued career interactions with engineers, academics, and past employers, mostly via workshops and conventions. Such opportunities are greatly appreciated, esp. per: Technip/Genesis, Wood Group, Deepwater Corrosion, LR, MEP/CSU, OIS/Oceaneering, YARD/BAeSEMA, TNPG, Manchester & Liverpool Universities, Unilever Resources, IMECHE, IMAREST, AMPP, EWB, … The arguments disseminated and opinions rendered are those of the author, given in good faith for knowledge sharing, informational, and educational purposes only. Recognizing the pioneering works of Professors G.C. Wood and TK Ross (UMIST), Professors S. Mannan and T. Kletz (TAMU), Prof. James Garber (ULL), Prof. F. Khan (MUN), B.R. Poblete, J.J. Cummings, B. Hall, A. Menarry, R. deJong, and many others. Finally, special thanks to Sonia Miles, Rachel Salked, Gavin Singh, Gina Hoeppner, Sheena Singh, Jason Hults, and James Miles for their inspiration.

No assurances/warranties are given nor implied, the reader assumes sole responsibility in all regards.

Feedback, comments, and suggestions, including new inputs and works as relevant, are welcome.

Appendix 48.A.1: Acronyms, Definitions, and Criteria

A number of useable criteria (near KPIs) are presented, along with brief definitions; most are discussed in References [1–26]. Engineering parameters are realigned to address climate change. Generally, these criteria are interdependent, although individual criteria can be used where justified. In principle, the new AI/ChatGPT approaches have tremendous upsides regarding the better formulation and use of ever-improving algorithms. There will be other criteria (pros/cons) and arguments as the science and engineering of climate change evolve.

• ALARP: Keeping the risk “As Low As Reasonably Practicable,” a potent tool, heading toward universal recognition. The Corrosion ALARP is a suitable adaptation for degradation phenomena, mainly via qualitative or semiquantitative characterization.
  
• Analogy-Cull-Adapt: Methodology to formulate and “prove up” important design criteria via non-dimensional variables (such as the Reynolds #) without major testing, utilizing systems based on fluid bypass loops and in-field test racks. Essentially, it is based on the “hydraulic scaling” works of Reynolds, Chilton, and Colburn among others.
  
• Artificial intelligence and machine learning (AI–MC): The crucial role of AI and the IoT in future engineering and technology development is emphasized. The use of ALARP procedures and best practices via risk analyses and code/recommended practice interactions between professions and societies are also emphasized, including the IOTs, AGI, ChatGPT, etc., with evidently the capacity to address/resolve most problems—essentially based on existing data, but also on more controversial regenerative data.
  
• Bypass loop/test rack: Once theory and practice hit the so-called tarmac, it is vital to be able to do in-field monitoring and inspection. The highly safety-sensitive industries such as nuclear, navy, aerospace, and offshore have largely bought into this after major engineering disasters. Done properly, the data so acquired can be an essential “prove up” ultimately leading to better ALARP risk-oriented solutions.
  
• CUE: Corrosion under excursions, often driven by operational excursions. Such hidden mechanisms are widely accepted, but rarely defined, and are often linked to stagnation/high velocity cycling, hot spot corrosion, nooks-&-crannies. CUE essentially helps break the simplistic material/chemistry approach by requiring a closer look at the pertinent physical parameters, such as flow dynamics (local turbulence, erosion, impingement, cavitation, etc.), stress patterns (including residual and fluctuating), fouling/scaling propensity, etc.
  
• C&IM: Corrosion and Integrity Management. The natural coalescence of corrosion and integrity management (IM) occurred once it was realized that IM was effectively up to 80% corrosion management—often referred to as CIM. The high visibility of materials, welding, and corrosion, honed since 1999, formalized post 2001, now very well appreciated in the design, commissioning, and operational phases, the latter including shutdown, storage, and decommissioning.
  
• FMECA: Failure Modes Effects, and Criticality Analyses, with close connections to HSSEQ$ and FSSL. Often, this is done only periodically or as a one off. Under impending new conditions, this must be done. It is recommended at least every 3 years, perhaps annually for a safety critical asset. A repeat FMECA must be recommended after any significant modal or mechanistic change, e.g., the appearance of a new degradation phenomenon (such as a microbial or fungal variant being introduced) or perhaps the loss of a key property, such as strength with temperature rise.
  
• FSSL: Fail Safe Safe Life (engineering criteria usually via predefined KPIs), a challenging combination, but a vital consideration under climate change. Overall FSSL is a useful thought process in the engineers’ toolbox, albeit often restricted by ROI, and hence, best ascribed as a goal-setting criterion. FSSL is closely linked to FMECA.
  
• HP/HT/HV: High pressure, high temperature, high velocity, a complex interaction with increased environmental relevance (polluting chemical species), temperature harshness, and greater recognition of powerful shearing forces (inside and outside pipes), including wet atmospheric winds. ASTM and API have prepared useful updates in recent years.
  
• HSSEQ$: Acronym to reflect Health, Safety, Security, Environment, Quality, and ($) being the monetization signal. HSSEQ$ is applied to minimize loopholes, grandfathering, and waivers, and has a close synergy to ROI.
  
• HAZOP: Hazards and Operability (best via multidisciplined* workshop)—The tool should be mandated to include corrosion engineers in a timely manner. Concepts of net zero carbon footprints may also fit in here.
  
• Note*: It is important to accept that such diversity of subject matter and indeed diversity of people will improve the relevance and quality of solutions and help eliminate often dangerous “group think.”
  
• ISD: Inherently Safe(r) Design, parallel to the concept of BAST—Best Available Safe(r) Technology. A complex area, more likely better appreciated as an attitude, as once reflected on by various coworkers (Poblete/Dalzell).
  
• Note: A related IRD, inherently reliable design, may also be included here to cover functionality.
  
• KPI: Key Performance Indicators (via major quantifiable technical and ROI drivers) with flexibility of boundaries per framework of societal norms and FSSL, and with link to Regulatory PINC—potential incidence of nonconformance.
  
• LL: Lessons learned, a vital concept still a rolling stone (gathering moss) and not fully applied. Also, may give valuable baseline and calibration “tweaks” to modeling and simulation studies. It is recommended that all projects including individual practicing engineers retain a notebook explaining and recording all lessons learned as they go.
  
• MAWT: Minimum allowable wall thickness (pipe, vessel, or structure), often linked to corrosion allowance (CA). Also, the crucial link between corrosion and integrity management (C&IM). This often invokes the use of concurrent design &/or MOC (management of change), project schedules, and asset changes of substance within FSSL.
  
• PTVσ: Pressure, temperature, velocity, stress. A complex interaction with increased harshness of environments; very importantly including corrosion fatigue. Flow regimes are expressed in terms of the Reynolds number (Re).
  
• ROI: Return on investment (economic performance criterion) and to include societal norms as they change in the impending new era of 5G introduction and opportunities. Flagging close synergy to HSSEQ$.
  
• SME: Subject matter expert—an overused definition, perhaps needing formal qualification—but hotly contested. Deploying SWOT analyses (strengths, weaknesses, opportunities, threats). A powerful resource per FSSL/HSSEQ$.
  
• TPR: Third-Party Review or TPV Third-Party Verification. A powerful multidisciplinary tool when effectively applied, may need mandates for high value, high safety, and integrity equipment. It is recommended that this must include the capability for “in field” monitoring, via a test station, such as a bypass loop or extended reach exposure rack. Since this is a controversial area, we might add that virtually all engineering disasters could be averted via a good TPV plan. Hopefully, the will to utilize this formally via a focused global regulation mandate may work, though the jury is still arguably out on this one.
  
• V: Velocity, and fluid turbulence, invokes use of nondimensional fluid analyses, and ideas of comparing known data to unknown data via field test stations and bypass loops (w/applied Reynolds–Chilton–Colburn type analogies). Pipe flows are quite established, but we must push the envelope for atmospheric flow assurance and corrosion vis-a-vis structures looking at the extremes of accelerated stagnation, i.e., zero fluid flow velocity (under shielding or containment) and extreme weather events, such as high wind velocity and shear, both linked to CUE.

Appendix 48.B.1: Main Corrosion Terms: Modes and Mechanisms

Showing a preliminary precis of the major recognizable corrosion mechanisms (from the original “Fontana 8” to now >20 (even approaching >25) with almost an annual revision, [e.g., 5, 7, 12, 26]. Those asterisked* may be the most stimulated under climate change, but climate change is a moving target. Most have or can be modeled or simulated, and perhaps all can be AI–ML quantified, integrated, and adjudged.

• General thinning (uniform): Rarely problematic, except at very high oxidation temperatures for mass thinning. Climate changes especially high-atmospheric temperatures, higher relative humidities (RHs), pollution, and vastly increased wind velocities (turbulence) will tend to facilitate accelerated general and localized thinning.
  
• *Pitting attack: Includes, Precorrosion/BOL/TOL), CUD/UDC, Spatter Linked Corrosion, Pitting clusters more dangerous. Climate change will tend to catalyze increased corrosion and degradation for all materials, including pipeline steels, CRA’s and the nonmetallics. The old and often controversial topic of pitting factors may need to be revamped as a practical way forward in the absence of a better fundamental understanding. The role of statistics and reliability studies may see a great leap forward in such regard.
  
• *Flow induced localized corrosion: (aka FILC and other acronym’s) A complex phenomena applicable to pipelines and structures for multiphase flows (energy, oil and gas, and atmospherics). The early works of Reynolds, Chilton and Colburn are good resources—which may have important empirical applicability in the lab and field [25].
  
• *Crevice corrosion: Includes occluded cells/dead legs, stagnation zones, hot spots, etc. Here, we may differentiate UDC as internal within pipes and vessels and CUD as external upon surfaces exposed to atmospheric conditions.
  
• *Stress corrosion related: Incl. SCC, SSC, HE/HIC SOHIC, etc. All can be accelerated by the new global climatic condition expectations—Especially regarding HT/HV/H_RH as integrated with high chlorides, bicarbonates, CO₂, SO₂ NOx, and other related species. Atmospheric pressures may also have a role, though not that clear just yet.
  
• *Corrosion fatigue: Incl. low and high cycle variations—Probably the least well understood, but likely the most dangerous—and applicable to all alloys/materials, especially where embrittlement may be induced.
  
• *MIC/fungal corrosion: Very dangerous; can be difficult to prove up. Noting that mechanisms may change for atmospherics, oil fields, on land, and subsea. Bacteria can metamorphize with associated corrosion and new colony deposition tuberculation.
  
• *Galvanic (mixed materials): Incl. Old steel vs New steel—Again noting that mechanisms may change for atmospherics, oil field, on land, and subsea, with major concerns in zones where inspection access is difficult.
  
• *Thermal stress-related corrosion: Essentially localized thermogalvanic—possible under restrained and unrestrained configurations. Primarily an onshore concern, but not to be discounted for unique unmanned wellheads and subsea. Major concerns in zones where inspection access is difficult.
  
• Creep phenomenology: Incl. loss of mechanical properties is a consideration for very high temperatures (>25 °C for the metallics and possibly far lower for the nonmetallics).
  
• Residual stress-related corrosion: Climatic considerations, often linked to PWC and temporary load malfunctions. Thermal imaging—if access allows—a powerful tool; and may be possible to estimate heat flux as well as surface temperatures.
  
• Filiform/under film (coatings) Corrosion: Tends to be cosmetic but can be penetrative. It might be enhanced under the new atmospheric conditions anticipated with climate changes.
  
• *Intergranular corrosion/selective phase: Incl. Fretting/Wear/Galling, Flange & Gasket Corrosion, Vibration, etc. These all likewise influenced as above firstly on a superficial level, thereafter more seriously.
  
• *Corrosion under insulation CUI: Incl. CUPS (under supports) with equivalency related to liner corrosion. This will certainly be enhanced under the new atmospheric physics anticipated with climate changes. Such localized cells (often un-inspectable and invisible) might lead to rapid failures hitherto not recognized. This is a major threat in high-consequence areas, especially where a pressure plant is involved.
  
• *Preferential weld corrosion (PWC): Incl. HAZ, PM, WM, and Brazing. Special concerns with changing climatology. Often with related erosion/impingement/cavitation flow Induced Corrosion. Such mechanisms may tend to self-modify for marine splash zones, on land, and subsea, with major concerns per configurations whereupon safe access inspection and monitoring is compromised, such as offshore soft tanks (magnetite issue), bridge box girders, hidden bolting, uninspectable crevices, etc.
  
• *CO₂/H₂S/TOL corrosion/erosion: Mainly regional offshore threat. The vast amount of work done and results from GOM should hopefully be shared for global advantage. The Ohio, Tulsa, Norsok models lead—though many energy company, private and commercial models continue to be advanced. The challenge remains predictability, accuracy, reliability and repeatability.
  
• *Regional soil corrosion and cracking: Variable “aggressivity” soils per low pH corrosion/SCC and high pH corrosion and caustic cracking. Often all stimulated by old versus new fertilizer and irrigation climate-related redistributions.
  
• *Corrosion under excursions CUE: Especially recompetitive passivation, pseudo passivity, and situational risk. Often dependent on MOC, human factors, specific situations, upsets, new anomalies, etc. Here, we expect more situational risks and corrosion/degradation stimulated under excursions out of the norm; hence, the idea of CUE.
  
• *Atmospheric corrosion: Now high profile per infrastructure as climate change continues. Most onerous being raised temperature (esp. beyond 50 °C with associated reverse polarities of certain alloys) higher wet wind/storm velocities, new challenges in quantifying turbulence and changes in polluting particulates, UV damage propensity, plus unique slip-related failure mechanisms within the new printed materials and composites.
  
• Stray current corrosion: Both DC and or AC interference—An old phenomena now revisited as such interactions increased by higher traffic/population densities via all means of transport, including electrical power distribution.
  
• *Old pipe/new pipe: Interfacial galvanic corrosion issue—The resurged rare phenomena of changing polarity’s under “new” climate conditions, e.g., unstable corrosion potential variations related to zinc, aluminum, perhaps other materials such as specific stainless steels, titanium alloys, and other alloys. This may impact on land and subsea pipelines—worthy of further research.
  
• *Hot spot corrosion: The relatively new but previously well-recognized phenomena of hot spot corrosion have now witnessed more attention. Here, we can surmise that any tight geometry or pocket, perhaps at lap joints, flanges, seals, or other, including specification breaks is a candidate for fluid stagnation or occluded cell-type crevice corrosion.
  
• Mixed material crevicing: In some instances, metallic to nonmetallic connections can yield bad outcomes; often hidden and thus a latent surprise awaiting discovery. Here, we see similar problems across assets, pipelines, buildings, bridges or other infrastructure. The role of related UV under climate change has been identified, though the results are thus far still under review.
  
• *Occluded cell activity: Closely linked to Hot Spot Corrosion; sometimes such “damp” zones if comprised of nonmetallic versus nonmetallic crevicing (including plastics, concrete, and wood) might lead to bacterial/mold/fungi/MIC build-up, with the associated threat of health issues if in close proximity to people. Previously, this was once identified as “sick building syndrome” and the fear here is that the “new new” conditions may give rise to such a resurgence if stimulated by oppressive HT/HV/H_RH, conditions; especially within high-rise buildings.
  
• *Physical loss of strength: This can be crucial, at critical but latent corrosion sites related to near coastal pipelines. Here design and maintenance can become far more important as is now sensibly established though still contested due to major cost implications ROI; so full prove-up still appears necessary.