The fabric
PVC-coated polyester, built as a sandwich
The floor and walls of a spill berm are not a plastic bag and not a PE tarp. They are a coated textile: a woven polyester scrim locked between two PVC layers, then cut and heat-welded into a tray.
What each layer does
| Layer | Job in a berm |
|---|---|
| Top PVC coating | Seals liquid, carries colour and the UV package, and is the face you clean. |
| Polyester scrim | Woven high-tenacity yarns take tear and tensile load when the berm is full or a wheel crosses it. |
| Bottom PVC coating | Second seal, weld face, and the side that sits on the ground or a ground mat. |
Why buyers should care
Two factories can both say “PVC”. One is selling banner stock; the other is welding a sump that has to hold diesel on a job site. The difference is the scrim, the coating formula, the weight, and whether the seams are welded.
Foam wall berms, tanker berms and flexible pallets on this site are cut from this sandwich in Taizhou. See foam wall spill berms.
What that build gives you
It holds liquid without stitch holes
PVC coatings fuse under heat. Floors and corners are high-frequency or hot-air welded, so the containment area is not sewn.
The scrim carries the load
A coating alone would stretch and split. The woven polyester takes the pull of a full berm and the abuse of folding and unfolding.
It folds for export
The sandwich stays flexible, so empty berms pack flat. That is why a factory in China can ship custom sizes without shipping air.
Weight is a spec, not a marketing word
Buyers quote 18, 22 or 28 oz/yd² (or the g/m² equivalent). Heavier fabric usually lasts longer where wheels and gravel meet the floor.
How the sheets become a berm
Panels are CNC-cut, then joined at the floor and corners. High-frequency welding or hot-air welding melts the PVC faces together. Foam, brackets or valves are added after the tray is closed.
Not the same as these
- PE / PE tarpaulin. Cheap covers and one-way tarps. Different polymer, usually sewn or taped, and not the same oil duty as a berm fabric.
- Advertising banner vinyl. Print fabric is coated for ink, not for diesel, folding fatigue or a welded sump.
- Unreinforced PVC film. A sheet with no scrim will tear at a corner or a valve. Berms need the woven core.
Colour (yellow for visibility, black for dirt and oilfield work) lives in the coating, not in the yarns. A custom colour still has to weld and fold; pigment is not a free extra.
Fabric weight
North American RFQs use ounces per square yard; European ones use grams per square metre. These are common berm specifications, not a stock list. Tell us the duty and we quote a weight.
| Specified as | g/m² | oz/yd² | Typical duty |
|---|---|---|---|
| 18 oz/yd² | ≈ 610 | ≈ 18 | Light duty, small trays, indoor drip control |
| 22 oz/yd² | ≈ 746 | ≈ 22 | Common foam-wall and portable berm spec |
| 28 oz/yd² | ≈ 949 | ≈ 28 | Drive-over floors, tanker berms, rough ground |
| 900 g/m² | ≈ 900 | ≈ 26.5 | European heavy-duty equivalent |
Liquids
PVC-coated polyester is the usual choice for diesel, lubricating oils and hydraulic fluids in portable berms. It is not a universal chemical liner. Gasoline, many solvents and aromatic hydrocarbons can swell or crack the coating.
Send the Safety Data Sheet with the RFQ. We check the liquid against the fabric before cutting. How to size the berm is a separate question from whether the fabric is compatible.
Questions about the fabric
Is this the same material as a truck tarp?
It is the same family — PVC on a polyester scrim — but berm fabric is specified for welding, folding and oil contact, not only for weather cover. Ask for the weight and a chemical check against the liquid you will contain.
Can a PVC berm hold any chemical?
No. PVC-coated polyester is commonly used for diesel, lubricating oils and hydraulic fluids. Gasoline, solvents and many aromatic chemicals attack PVC. Send the Safety Data Sheet before you order.
What does 22 oz/yd² actually mean?
It is the mass of the finished sandwich (both coatings plus the scrim) per square yard. European quotes use g/m². 22 oz/yd² is about 746 g/m². It is not the thickness of the yarns alone.
Why not sew the seams?
A needle leaves a hole. Thread wicks liquid. Berm floors and corners are heat-welded so the PVC coatings melt into one seam.
Quote a weight and a size
Send the inner size, the liquid (with SDS if you have it), the quantity and the destination. We reply with a fabric weight and a price.