Case Study 2: Caking and Clumping in Container Shipment¶
Background¶
- Product: Paprika Powder, Premium Grade (ASTA 160–200)
- Quantity: 1 × 20' FCL (10 MT)
- Packaging: 25 kg PP laminated bags, 400 bags on 10 pallets
- Shipment Route: Qingdao, China → Lagos, Nigeria
- Incoterm: CIF Lagos
- Shipping Date: August 2024 (peak summer, high humidity season)
The Issue¶
Upon arrival at Lagos port (35 days transit), the buyer reported that ~60% of bags showed visible caking. The product could not be emptied freely from the bags — large clumps of 10–20 cm diameter had formed. The buyer declared the shipment partially unfit for use and demanded 30% compensation.
Initial Assessment¶
The QC team reviewed documentation:
| Document | Result |
|---|---|
| Pre-shipment moisture test | 7.2% (well within ≤10% spec) |
| Pre-shipment packaging inspection | Pass: all bags sealed, pallets stretch-wrapped |
| Container pre-loading inspection | Clean, dry, no odor |
| Bill of Lading | No remarks on container condition |
| Temperature log | Not available — container was not equipped with data loggers |
The product left the factory at specification. Something happened during the 35-day voyage.
Root Cause Investigation¶
Step 1: Climate Analysis¶
August–September 2024 shipping route conditions:
| Segment | Duration | Typical Temp | Typical RH |
|---|---|---|---|
| Qingdao → Shanghai (loading) | 2 days | 28–32°C | 75–85% |
| Shanghai → Singapore | 7 days | 29–33°C | 75–90% |
| Singapore → Cape Town | 12 days | 22–28°C | 70–80% |
| Cape Town → Lagos | 14 days | 24–30°C | 80–95% |
The route passed through two high-humidity zones (East China Sea and Gulf of Guinea) with a total transit of 35 days through tropical conditions.
Step 2: Container Dew Point Analysis¶
A standard 20' container experiences diurnal temperature cycling:
- Daytime metal container wall temp: up to 45–50°C in direct sun
- Nighttime: cools to 25–28°C
- This creates a dew point breach — moisture condenses on container walls and the top layer of bags
The physics: The air inside the container at 35°C and 80% RH holds ~32 g/m³ of water vapor. When the container cools to 25°C at night, saturation drops to 23 g/m³. The excess 9 g/m³ condenses as liquid water. In a standard 20' container (33 m³ airspace), that's ~300 mL of liquid water per night — equivalent to pouring a can of soda onto the cargo every night for 35 nights.
Caking is a known phenomenon when paprika powder absorbs just 1.5–2% additional moisture above its baseline. At 7.2% initial moisture, absorption to 9%+ triggers caking. The condensed water wetted the bag surfaces, moisture migrated inward, and the powder rehydrated enough to bridge particle surfaces.
Step 3: Packaging Assessment¶
The PP laminated bags used had: - Outer PP weave: water-resistant but not waterproof - Inner PE liner: 0.05 mm thickness - Result: The PE liner proved insufficient under sustained condensation exposure. Moisture vapor migrated through the PP weave and condensed between the liner and the powder surface.
Root Cause Confirmed¶
Thermal cycling in tropical shipping combined with insufficient moisture barrier packaging caused gradual moisture ingress and powder caking. The primary factor was not pre-shipment quality but logistics conditions.
Corrective Actions¶
| Action | Detail | Owner | Status |
|---|---|---|---|
| 1. Desiccant protocol | Add 2× 500g silica gel desiccant bags per pallet, secured inside stretch wrap | Warehouse | Implemented Sep 2024 |
| 2. Laminated bag upgrade | Increase PE liner from 0.05 mm to 0.08 mm with metallized outer layer | Procurement | Implemented Oct 2024 |
| 3. Container pre-cooling | Pre-cool empty container to 20°C for 2 hours before loading (reduces initial temperature differential) | Logistics | Implemented Sep 2024 |
| 4. Ventilation protocol | Reefer container recommendation for tropical destinations (surcharge ~$500); ventilated container as fallback | Sales | Implemented Nov 2024 |
| 5. Moisture indicator cards | Place 3M humidity indicator cards at front, middle, and rear of each container | QC | Implemented Oct 2024 |
Results After Corrective Actions¶
Monitoring data for subsequent tropical shipments (n=12):
| Metric | Before (Jan–Aug 2024) | After (Sep 2024–Jun 2025) |
|---|---|---|
| Caking incidents | 3 of 7 shipments (43%) | 1 of 12 shipments (8%) |
| Customer complaints re: moisture | 4 | 1 |
| Cost per shipment for desiccants + packaging upgrade | $0 | ~$180 |
| Cost savings per potential claim avoided | $0 | ~$3,000–$6,000 |
The lone post-improvement incident was traced to a container with a damaged door seal — now added to the pre-loading checklist.
Lessons Learned¶
- Never underestimate tropical trade lane risks. A product that ships fine to Europe or North America may fail on West African or Southeast Asian routes.
- Packaging decisions should be route-specific, not one-size-fits-all. The marginal cost of upgraded packaging + desiccants ($0.02/kg) is trivial compared to claim risk.
- Moisture indicator cards cost pennies and provide definitive evidence. In the single post-fix incident, the indicator cards showed "wet" at the rear door area (near the damaged seal), proving the failure was container-related, not product-related.
- Pre-cool the container — this single step was credited by the logistics partner with reducing the temperature differential by ~60%.
Supporting Documents¶
- CAPA Report: CAPA-2024-012
- Container Pre-Loading Inspection Checklist: container-loading-inspection.md
- Moisture Indicator Card Reading Guide (internal SOP-DIN-QC-024)
- Packaging Specification Revision v3.1 (Oct 2024)
- Shipper's Temperature Data for Route QIN-LOS (China Shipping Logistics, Reference R021-2024)
This case study is based on a composite of real incidents experienced by Dinweys across multiple tropical trade lanes. Specific details have been generalized.