How often should a Case Internal Divider be inspected?

Every 90 days or 500 openings, whichever comes first, and always at discharge after a voyage.

The foam stiffened after washing. Can it stay in service?

Alkaline detergent or hot air usually explains it. Above 8 percent compression set, replace; between 5 and 8 percent, move the block to a case carrying light items.

One panel in the Case Internal Divider broke. Replace just that one?

Yes, from the same batch and thickness. Thickness varies by 0.15 mm between batches, so a new panel sits tight while the old ones take all the movement.

White rust showed up in the slots. Replace now?

White rust is early zinc corrosion. Wipe it off: no pitting means one descaling pass, brown powder means the slot needs rework.

After 45 Days at Sea: Case Internal Divider Checks

Quick answer: after 45 days at sea a Case Internal Divider fails at the slot mouths and in the foam, not in the panels. Inspect every 90 days or 500 openings, and replace at 8 percent compression set, 3 mm deflection under 20 N, or a slot radius worn to R1.2.

Where a Case Internal Divider Fails First at Sea
Six Checks After Every Unpacking
Cleaning Salt Residue and the Drying Curve
Replacement Lines: 3 mm, 8 Percent, R1.2
Stretching Service Life: Spares, Storage, Refurbishment
FAQ

1. Where a Case Internal Divider Fails First at Sea

Last winter a batch of equipment cases ran 45 days to Europe. Hold temperature swung from 5 °C to 48 °C, humidity sat at 85 percent, and the cases were stacked three high. Nothing had broken, yet every fault sat on a contact surface: dents in the EVA blocks, panels rocking in their slots, damp foam.

Wet heat hurts foam most: EVA above 90 percent closed cell dries slowly, while open-cell PE gains 3 to 5 percent of its weight in 45 days. Damp foam loses a hardness grade and the preload goes, so the panels start to move.

Symptom	Cause	Field measurement	Rejection line
Dents in blocks	Load plus softening above 40 °C	Steel rule on the face	Deeper than 2 mm
Panels rock	Worn slot mouth	0.3 mm feeler, one side	Clearance above 0.8 mm
Foam feels heavy	Absorbed moisture	Weigh against a dry block	Gain above 3 percent
Panel bulges	Creep from overload	Press 20 N, measure residual	Residual above 3 mm

2. Six Checks After Every Unpacking

Six fixed actions, four minutes per case, always in the same order.

Case Internal Divider: black hard-shell case in front view on white, two yellow latches, an arc handle recess and thin ribs above and below it

Read the slot. The 2 mm band at the panel edge is the wear zone; a burr leads to the next check.
Gauge clearance. At 0.8 mm the slot is rounded and force has fallen below 20 N.
Press the panel. 20 N mid-span, about two water bottles. Residual above 3 mm means creep.
Pinch the foam. Rebound slower than 2 seconds, or a print deeper than 2 mm, means spent foam.
Weigh a block. A 3 percent gain over a dry reference sends the batch to drying.
Probe the adhesive. A 0.2 mm feeler entering 15 mm along the seam.

Monthly for the first two checks, quarterly for the rest.

3. Cleaning Salt Residue and the Drying Curve

A 96 hour salt spray test white-rusts zinc bracket edges and pits stainless springs in crevices. Cleaning pulls chloride out of the gaps, not shine into the shell.

Use neutral detergent at pH 6 to 8, 2 percent, in water no hotter than 40 °C; soak 3 minutes and brush along the slot, never across it.

Tap water runs above 300 µS/cm and dries into a salt film, so rinse with deionised water below 50 µS/cm.

Sunlight chalks EVA after 200 hours of UV and closed cells shrink above 65 °C, so dry with six hours of air at 40 °C.

Item	Medium	Temperature, time	Do not
EVA blocks	Detergent 2 percent	40 °C, 3 minutes	Wring out
PP panels	Detergent 2 percent	40 °C, 3 minutes	Steel wool
Zinc brackets	Detergent plus 0.5 percent inhibitor	Ambient, 2 minutes	Acid pickling
Gasket	Plain water	Ambient, 1 minute	Any grease but silicone

4. Replacement Lines: 3 mm, 8 Percent, R1.2

Three lines cover shape, rebound and fit; break one and the part goes.

Case Internal Divider: translucent milky-white case on white, two red latches, cavity faintly visible through the shell, black panel edge at left

Compression set at 50 percent, 23 °C, 22 hours: new blocks read 3 to 5 percent. Past 8 percent the block stops returning, cell height varies by 1.5 mm, and long items jam in.

Slot radius: new is R0.5. At R1.2 the contact area has doubled, insertion force drops from 45 N to 18 N, and the hand feels no bite. Replacing the panel does nothing; the wear sits in the slot.

Fit: close, invert, shake three times. Up to 2 mm is acceptable; past 3 mm the preload is gone.

Labour decides how the line is applied: one block takes 6 minutes, a full panel set 40, so on a 12 cell case the fourth block already costs more than a set.

5. Stretching Service Life: Spares, Storage, Refurbishment

Gains come from slowing wear, not from repairing it.

Hold spares at 8 percent of the fleet, same batch and mould number, since batches vary by 5 Shore C.
Store flat, four high at most; standing puts foam weight on the lower edge and leaves a line in three months.
Keep stores at 45 to 55 percent humidity, away from the wash bay.
Lay panels flat once out, since leaving them slotted creeps the slot.
Refurbish slots once, R0.5 to R1.0; a second hot press at 140 °C costs 15 percent of rebound.

Mark refurbished blocks separately in the record.

Conclusion

Maintaining a Case Internal Divider is a race against three decays: foam rebound, slot radius and panel creep. Inspection sets the interval, cleaning sets the environment, the replacement lines set the floor. Write 8 percent, 3 mm and R1.2 into the work instruction, and the Case Internal Divider becomes a part you schedule, not a failure you discover.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.