technical case study
piping systems commonly fail at heat-affected weld zones or dead-leg sections where oxygen depletion occurs. Material selection remains important, but the report stresses that fabrication quality ultimately determines performance. For applications within 500 m of the coast, duplex stainless steels are strongly preferred, while 316 may still be acceptable under carefully controlled fabrication conditions. Grade 304 is generally considered unsuitable in these zones. Further inland, exposure severity decreases, allowing broader use of 316 and, in some cases, 304. However, the report warns that poor fabrication practices can undermine the performance of any alloy grade regardless of theoretical corrosion resistance. The publication concludes that the stainless steel industry must shift its focus away from simply upgrading alloys whenever corrosion appears. While specifying more noble and expensive materials may sometimes mask underlying problems, it does not necessarily solve them. Instead, the report argues that South Africa’s coastal corrosion challenge should be approached through disciplined fabrication, proper surface treatment and a deeper understanding of passive layer behaviour. In practical terms, the message to the industry is clear: stainless steel success on the South African coast depends less on what alloy is selected and more on how that alloy is handled before it reaches service.
To address these risks, the guide proposes a strict fabrication checklist for coastal applications. Recommended controls include dedicated stainless steel- only tooling, controlled welding procedures, complete heat tint removal, mandatory pickling and passivation, smooth low-roughness surface finishes and rigorous final cleaning before handover. “In South African coastal environments, stainless steel succeeds or fails at the passive layer.” Common problems The guide also highlights recurring problems in common coastal applications. Architectural balustrades often experience rust bleeding from welds and tea staining on horizontal rails due to inadequate weld finishing and poor drainage design. Tanks frequently suffer pitting along weld seams or shell-to-floor junctions where poor surface preparation and insufficient cleaning allow chlorides to concentrate. Fasteners are especially vulnerable when incorrect materials or contaminated components are used, while
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Issue 2 – 2026
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