Sep 10, 2026
Nano Insulation Board Incoming Inspection: A QC Checklist for Every Shipment
A practical incoming inspection routine for microporous nano insulation boards — document check, packaging and moisture, dimensional tolerance, visual defect criteria, density and thermal verification
Most quality problems with microporous insulation are not created in the factory. They are created in transit, in a container, or in a warehouse — and they are invisible until the board is already cut and fitted. By then the claim is hard to make and the reline schedule has already slipped.
This is the incoming inspection routine we recommend to every plant that buys high-strength nano insulation boards from us or from anyone else. It takes about two hours for a full container and it catches essentially everything that matters.
Why incoming inspection is worth two hours
A rejected board costs you the board. A board that reaches the ladle before anyone notices it is cracked costs you the cut pieces, the fitting labour, the anchor hardware, and two or three days of schedule. The failure mode is rarely dramatic — it is a hairline through-thickness crack that opens on first heat-up, or a batch that absorbed moisture in a humid port and now weighs more than the specification allows.
If you are still at the purchasing stage, the five buying mistakes guide covers what to lock down in the order documents. This checklist picks up where that leaves off: the crate is on your dock.
Before the truck arrives: document check
Do this the day before delivery, not while the driver is waiting.
Certificate of analysis (COA) with the batch number, production date, and the actual measured values for density, thermal conductivity and permanent linear change. A COA that only restates the specification range is not a COA.
Packing list matching the crate marks. Crate numbers should run sequentially and match the count on the bill of lading.
Bill of lading and, for sea freight, the container number and seal number. Photograph the seal before it is broken.
Confirm the grade on the COA matches what you ordered. Where mean service temperature runs above 1000 C, the order should be SLM-1200; anything rated lower will shrink and crack in that service.
If the COA is missing, do not unload into production stock. Unload into a quarantine area and request the document.
Step 1: packaging and moisture
The crate is the first piece of evidence and the last thing most people photograph.
Photograph each crate from two angles before opening, including the crate marks and any damage to the outer wrapping.
Open one crate and read the humidity indicator card immediately. A card showing above 60 percent means the boards may have picked up moisture. Note the reading before it equilibrates with your ambient air.
Check that edge protectors are intact on all four vertical edges and that the boards are separated by interleaving rather than stacked board-on-board.
Look for water staining on the crate base. A board that sat in standing water during a typhoon transshipment will not look wrong on the outside but will be heavy and will steam on first heat-up.
Moisture is the single most common transit damage we see on sea freight, and it is almost always detectable at this step if someone looks.
Step 2: dimensional check
Pull a sample of at least five boards per crate, taken from the top, middle and bottom of the stack.
Standard ladle back-up boards are 1200 x 600 mm, commonly 50 mm thick. Measure length, width and thickness at both ends and the centre.
Length and width tolerance of plus or minus 2 mm is normal and is already assumed in the joint layout. Thickness tolerance of plus or minus 1 mm on a 50 mm board is the practical limit.
Check squareness by measuring both diagonals. A difference of more than 3 mm on a 1200 mm board indicates the stack was compressed in transit or cut out of square at the factory.
Record the actual thickness you received. If the shipment averages 48 mm where you specified 50 mm, the thermal resistance of the lining drops measurably, and that belongs in your ROI calculation rather than in a surprise at the next campaign.
Step 3: visual defect criteria
This is where a written acceptance rule saves arguments later. Agree the rule with your supplier before the shipment, not after.
Through-thickness cracks: reject. A board cracked all the way through has lost its structural integrity and will not hold on anchors.
Edge chips deeper than 8 mm or longer than 50 mm: set aside for evaluation. These can usually be cut around if you have the length, but they should not go into a curved section.
Surface marks, light scuffing and small corner nicks under 8 mm: accept. These do not affect thermal performance.
Delamination or a soft, powdery surface: reject. That is either moisture damage or a pressing defect, and both will get worse on heat-up.
Visible colour variation across one board: usually acceptable, but check the density on that specific board — it can indicate uneven pressing.
A practical rejection rate for a well-packed shipment is under 2 percent. Above 5 percent, stop unloading and contact the supplier with photographs.
Step 4: density and weight
Weigh a full board and calculate the bulk density. Microporous board for ladle back-up typically falls in the 220 to 300 kg per cubic metre range depending on grade; compare against the value on your COA, not against a generic figure.
A board weighing more than the COA value plus 5 percent has most likely absorbed moisture.
A board weighing significantly less than the COA value indicates a pressing or formulation problem, and its thermal conductivity will not match the certificate.
Weigh boards from the bottom of the crate as well as the top. Bottom boards carry the load in transit and are the first to show compression damage.
Step 5: thermal conductivity verification
Most plants cannot run a guarded hot plate on site, and that is fine. What you can do is a comparative check that catches gross errors.
Keep one retained sample board from every shipment, labelled with the batch number and date.
Once or twice a year, send retained samples to a third-party laboratory for thermal conductivity at your actual mean service temperature. This is the check that validates all the COAs you have been accepting.
On site, a simple comparative test works: place a retained board and a new board on the same hot surface and read the cold-face temperature with a contact probe after a fixed interval. A new board that runs more than 10 C hotter on the cold face than your retained reference is worth a laboratory test.
Where the grade has been specified for higher temperatures, our SLM-1000 vs SLM-1200 comparison guide explains how the conductivity curves diverge with mean temperature.
Step 6: permanent linear change
If your laboratory can run it, a permanent linear change test at the specified service temperature for 12 hours is the most informative single test on a microporous board.
A well-made board should show permanent linear change under about 2 percent at its rated temperature.
Shrinkage above that means the board will pull away from its neighbours on first heat-up and open a joint — exactly the failure the installation guide tries to prevent with deliberate 1 to 2 mm gaps.
If you cannot run the test, note that a board which has already shrunk in service will show a gap pattern that widens from the hot face. That is a service observation, not an incoming test, but it tells you the same thing.
What to do with non-conforming material
The claim window is short, so the process matters more than the argument.
Photograph everything before moving it: the crate, the crate mark, the humidity card, the defect with a scale reference, and the COA.
Quarantine rejected boards in a clearly marked area. Do not return them to the production stack "for later evaluation" — they will get used.
Notify the supplier within the contractual claim period, usually seven to fourteen days from delivery. Include the batch number, crate number and photographs.
Do not install non-conforming board and then claim. Once it has been cut and heated, virtually no supplier will accept the claim.
Storage after inspection
Passing inspection is not the end of the process.
Store under cover, off the concrete floor on battens, away from steam lines and open water.
Keep relative humidity below 75 percent. In a coastal plant during the wet season this usually means a dehumidified store, not just a roof.
Rotate stock by production date. Microporous board has a long shelf life when dry, but first-in-first-out costs nothing and removes the question.
Re-check the humidity card if boards sit for more than three months before use.
A one-page version for the dock
If you want something to laminate and hand to the receiving crew, this is the minimum set:
COA present, batch number matches, grade matches the order.
Humidity indicator card below 60 percent.
Dimensions within plus or minus 2 mm on length and width, plus or minus 1 mm on thickness.
No through-thickness cracks, no delamination, no soft powdery surface.
Board weight within 5 percent of the COA value.
Photographs of every crate taken before opening.
That list catches the large majority of real problems in under two hours for a full container, and it gives you the evidence you need if something does go wrong.
If you would like our incoming inspection sheet as a fillable template, or want the acceptance criteria written into your next order, contact us with your ladle size and service temperature. We will also confirm whether SLM-1000 or SLM-1200 is the right grade for your conditions, and how the anchored ladle back-up assembly should be laid out.
For reference on how the material is made and why the tolerances above exist, see How SLM nano insulation boards are manufactured, and for how it compares with the alternatives you may be replacing, see Nano insulation board vs ceramic fiber board.
— The Suleiman Refractory Engineering Team
