{"id":1256,"date":"2026-05-29T02:38:47","date_gmt":"2026-05-29T02:38:47","guid":{"rendered":"https:\/\/baowu-steel.com\/?p=1256"},"modified":"2026-05-29T02:39:53","modified_gmt":"2026-05-29T02:39:53","slug":"bw-fi-afr-019-anaerobic-black-spot-corrosion-in-west-africa","status":"publish","type":"post","link":"https:\/\/baowu-steel.com\/bw-fi-afr-019-anaerobic-black-spot-corrosion-in-west-africa\/","title":{"rendered":"BW-FI-AFR-019: Anaerobic Black Spot Corrosion in West Africa"},"content":{"rendered":"

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BW-FI-AFR-019: Anaerobic Black Spot Corrosion in West Africa<\/h1>\n

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Critical Finding: Standard sea\u2011freight packaging fails catastrophically during prolonged congestion at Lagos ports. After 45+ days at 90%+ RH, anaerobic black spot corrosion penetrates the zinc layer. Only Vertical Eye\u2011to\u2011Wall (VEW) sealed packaging eliminates the humid, oxygen\u2011depleted microenvironment responsible for this failure.<\/strong><\/p>\n

This case study investigates the recurrent black spot corrosion on galvanized steel coils stranded at Apapa & Tin Can Island ports, Lagos. Through root\u2011cause analysis of the unique West African logistics chain, we establish a mandatory packaging upgrade that has proven zero\u2011defect delivery in over 200 shipments.<\/p>\n

<\/p>\n\n\n\n\n\n\n\n\n\n\n\n
AFR-019 Failure Case & Solution Comparison<\/caption>\n
Parameter<\/th>\nStandard Packaging (Failure)<\/th>\nVEW Sealed Packaging (Solution)<\/th>\n<\/tr>\n<\/thead>\n
Destination<\/td>\nLagos (Apapa \/ Tin Can), Nigeria<\/td>\nLagos (Apapa \/ Tin Can), Nigeria<\/td>\n<\/tr>\n
Average Port Dwell Time<\/td>\n45\u201360 Days<\/td>\n45\u201360 Days<\/td>\n<\/tr>\n
Ambient RH (Rainy Season)<\/td>\n90\u201395% RH<\/td>\n90\u201395% RH<\/td>\n<\/tr>\n
Packaging Type<\/td>\nStandard seaworthy wrap (PE film + desiccant)<\/td>\nVertical Eye\u2011to\u2011Wall (VEW) sealed packaging<\/td>\n<\/tr>\n
Corrosion Onset<\/td>\nBlack spots visible from day 35<\/td>\nNo corrosion after 120 days<\/td>\n<\/tr>\n
Root Cause<\/td>\nAnaerobic micro\u2011climate inside eye cavity<\/td>\nOxygen and humidity locked out<\/td>\n<\/tr>\n
Result<\/td>\nFAIL \u2013 Claim<\/td>\nPASS \u2013 Zero Defect<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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The Lagos Port Reality: A Corrosion Accelerator<\/h3>\n

Apapa and Tin Can Island ports in Lagos are notorious for extreme congestion, particularly during the rainy season (April\u2013October). Coils routinely sit exposed to 90\u201395% relative humidity<\/strong> for 45\u201360 days<\/strong> awaiting clearance. Under these conditions, standard seaworthy packaging becomes a liability.<\/p>\n

Conventional packs use a PE film wrap and desiccant bags. While effective in ventilated holds, the trapped air inside the coil\u2019s eye quickly becomes stagnant. The combination of high humidity, warmth, and restricted air exchange creates an anaerobic microenvironment<\/strong> where sulfate\u2011reducing bacteria thrive and electrochemical reactions proceed without atmospheric oxygen renewal. The result is a distinct black corrosion product (magnetite and iron sulfide)<\/strong> that pits the zinc and steel.<\/p>\n

Why Standard Packaging Fails in West Africa<\/h3>\n

Desiccant absorbs moisture initially, but their capacity is finite. Once saturated, the sealed environment becomes a condensation trap. The eye cavity is particularly vulnerable because it holds the core temperature longer, promoting cold\u2011wall condensation. Black spot corrosion is the visible symptom of a completely overwhelmed protection system.<\/p>\n

The Vertical Eye\u2011to\u2011Wall (VEW) Sealing Solution<\/h3>\n

Baowu Steel\u2019s VEW packaging re\u2011engineers the coil protection for extreme tropical logistics. Instead of relying on desiccant, the coil is secured with the eye axis vertical<\/strong> and the entire package is hermetically sealed to the pallet wall. This configuration:<\/p>\n