[ End User Interview ]
[ End User Interview ]
observed cases where electrical currents travel through the system and cause localised corrosion at field joints,” he says.“ It took us years to fully understand and validate this mechanism. This form of corrosion occurs both inside our production plants, and externally in the field.” Externally, pipelines are exposed to harsh desert conditions, including saline soils and high humidity.“ Subsurface corrosion, cathodic protection shielding, and coating degradation are all challenges we encounter,” he adds.
Material selection: the role of stainless steels and CRAs Material selection at PDO is driven by a combination of technical performance, lifecycle cost, and operational considerations.“ Our first choice, where possible, is non-metallic materials,” Dr Nabhani explains.“ We have non-metallic flowlines that have been operating for 30 years without inspection, with excellent performance.” However, non-metallics are not suitable for all applications, particularly at higher pressures, temperatures, or diameters. In such cases, metallic materials become necessary. Stainless steels and duplex grades play a central role in PDO’ s material strategy.“ We use 316L stainless steel extensively for piping and components within facilities,” he says.“ However, for flowlines and pipeslines we rarely select 316L due to the strength requirements, so in these situations duplex stainless steel is widely applied.” The scale of duplex deployment at PDO is significant.“ We install well over 100 km of duplex pipelines per year,” Dr Nabhani notes.“ Over the past decade, that amounts to approximately 1,500 km.” For more aggressive environments, higher alloy materials are required.“ When H 2 S levels exceed the limits of duplex stainless steel, we move to nickel alloys such as 625 or 825,” he explains.“ These materials are more expensive, but they provide higher reliability and reduce the need for ongoing inspection.” Clad and weld-overlay solutions are also widely used, particularly for vessels and large-diameter piping.“ We typically use 316L stainless steel or Alloy 625 for cladding,” he says.“ More recently, we have also introduced Alloy 825 in certain applications.” Super duplex and 6Mo alloys are used selectively in highly corrosive environments, particularly where oxygen
Dr Naghani served as Lead Materials and Corrosion Engineer on the USD 4.5 billion Rabab Harweel Integrated Project, defining material selection strategies in this highsour, high-chloride environment. Photo © PDO
ingress or high chloride levels are present. However, Dr Nabhani notes that these materials come with challenges in terms of cost, availability, and weldability.“ In the past, we also used 304 stainless steel, but we faced limitations due to its lower resistance to pitting corrosion,” he adds.“ We now use it much less frequently.”
Supply chain realities and constraints Despite the growing demand for CRAs, supply chain challenges remain a key concern.“ Cost is always a challenge, especially when the number of qualified vendors is limited,” Dr Nabhani says.“ Less competition can drive prices up.” Lead times are another critical factor.“ CRAs are not like carbon steel- you need to plan well in advance,” he explains.“ For nickel alloy components, lead times can extend to two years.” PDO has adopted a strategic approach to supplier management, aiming to ensure both cost competitiveness and security of supply.“ We try to have at least three qualified vendors for each category,” he says.“ And we avoid relying on a single region.” This approach reflects lessons learned during recent global disruptions, including the COVID-19 pandemic.“ It’ s important to diversify geographically,” Dr Nabhani adds.“ If something happens in one region, you don’ t want your entire supply chain to be affected.”
Future directions: materials, inspection & innovation Looking ahead, Dr Nabhani identifies several areas where further development is needed.
“ We would like to see new material grades with lower cost,” he says.“ For example, materials that sit between duplex, 6Mo, and nickel alloys.” Expanding the operating envelope of existing materials is another priority.“ If duplex stainless steel could handle higher H 2 S levels, it would unlock significant value,” he explains. Inspection technology is also an area of focus.“ Inspection of CRA materials is still challenging,” Dr Nabhani notes.“ We need more advanced techniques and greater confidence in integrity assessments.” He also highlights the potential of additive manufacturing.“ If we can produce critical components locally, it could significantly reduce lead times,” he says.“ This is particularly important for spare parts and obsolete equipment.”
Strengthening collaboration Finally, Dr Nabhani emphasises the importance of closer collaboration between end users, suppliers, and researchers.“ I would like to see more engagement between manufacturers and end users,” he says.“ If engineers from suppliers spend time in operating facilities- and vice versa- it would improve understanding and lead to better solutions.” He also highlights the role of industry events and knowledge sharing.“ Conferences such as Duplex World are important for bringing together different perspectives; end users, manufacturers, and academia,” he notes.“ There are still many opportunities to improve collaboration.” Concluding, he adds:“ By working more closely together, we can address challenges more effectively and create real value for the industry.”
22 Stainless Steel World May 2026 www. stainless-steel-world. net