Industrial Rubber Sheets Types

On-site quick reference to avoid buying the wrong sheet under emergency repairs

Introduction
On emergency repairs you’ll often hear: “Just slap a rubber sheet on it” or “Why has it swollen again?” Rubber sheets are not generic “rubber skins.” Formulation, cure state and filler system matter — one wrong choice and an oil-resistant requirement becomes severe swelling; insulation becomes conductive. I’ve taken 17 sheet types through refinery, steelworks, ore dressing and PV workshops. Below is a three-line index you can use on site: Key property → Compatible media → Typical workstation. Look up by operating condition and you’ll rarely order the wrong sheet.

1. Four basic rubber families and hardness ranges

1.1 NR / SBR — General purpose sheet

• Hardness: 55–75 Shore A

• Tensile: ≥ 6 MPa; Elongation at break: ≥ 300%

• Service temp: −30 to 70 °C; Chemical tolerance: pH 3–10

• Typical uses: belt cushion pads for mines, anti-slip warehouse floor mats

• Warning: mineral oil immersion (72 h) → ~120% volume swell. Do not use for pump inspection pits.

1.2 NBR — Oil-resistant sheet (nitrile rubber)

• Acrylonitrile (ACN): 28% (mid-high nitrile)

• Hardness: 65–80 Shore A

• Oil resistance: No.3 oil at 100 °C × 72 h → ≤10% volume change

• Typical uses: pump outlet flange gaskets in refineries, hydraulic pipe hanger pads

• Tip: low-temperature formula with DOA plasticizer retains ~20% elongation at −30 °C — suitable for outdoor northern climates.

1.3 CR — Weather-resistant sheet (chloroprene / Neoprene)

• Polymer content: ≥ 55%

• Ozone resistance: no cracking at 50 pphm, 40 °C × 72 h

• Typical uses: desulfurization duct compensator cushions, PV mount vibration pads

• Extra: self-extinguishing — after flame removal self-extinguish ≤ 5 s; qualified for welding fire curtains (GB/T 13489-92).

1.4 EPDM — Heat & weather resistant sheet

• Ethylene content: ~55%; peroxide cure system

• Hardness: 60–75 Shore A

• Aging: 120 °C × 168 h → tensile retention ≥ 85%

• Typical uses: turbine casing seals, hot-water pipe hangers and anti-vibration pads

• Caution: EPDM is not oil-resistant — diesel immersion 24 h → ~150% swelling; do not mix EPDM and NBR in same sealing assembly.

2. Functional specialty sheets — make “special” routine

2.1 Insulating sheet

• Formula: NR + SBR, high purity

• Volume resistivity: ≥ 10¹⁴ Ω·cm; Dielectric strength: ≥ 30 kV/mm

• Color cue: must be red or green for instant visual ID

• Use: switchroom floors, 1 m safety mats in front of high-voltage cabinets

• Acceptance: sample 1 m², 20 kV / 1 min withstand, leakage ≤ 5 mA

2.2 Anti-static sheet

• Additives: carbon black + antistatic agent

• Surface resistance: 10⁶–10⁸ Ω — discharges static without heavy leakage

• Use: explosives magazine floors, electronics handling tables

• Note: black may rub off carbon black — recommend 0.3 mm polyurethane topcoat so hands don’t stain.

2.3 Food-grade sheet

• Standard: GB 4806.11-2016; overall migration ≤ 10 mg/dm²; KMnO₄ consumption ≤ 10 mg/kg

• Color: white or blue (blue tracer masterbatch detectable by metal detector)

• Use: dairy conveyor tops, slaughterhouse cutting boards

2.4 High-temperature silicone sheet

• Material: methyl-vinyl silicone rubber

• Service: continuous 230 °C, short-term 300 °C

• Hardness: 50 Shore A; rebound: 60%

• Use: hot-press pads for solar laminators, injection-molding platen cushions

• Limit: tensile only ~5 MPa — poor cut resistance; avoid as structural gasket.

2.5 Acid/base resistant fluororubber (FKM)

• Type: two-component FKM

• Hardness: 75 Shore A

• Chemical: 98% H₂SO₄ × 23 °C × 168 h → mass change ≤ 3%

• Use: electrolytic cell seals in hydrometallurgy, manhole gaskets on spent-acid tanks

• Cost: ~20× NR — use only at concentrated corrosion points; don’t blanket-cover large areas.

3. Structure-reinforced sheets: fabric, wire or steel inserts

3.1 Fabric-reinforced (NN-200)

• One nylon ply; lateral strength to ~15 MPa — ideal for thin sheets <3 mm used as shaped gaskets; punching doesn’t crumble.

3.2 Wire-reinforced (ST-630)

• Steel wire spacing 10 mm, tear strength ~120 kN/m — used for undercarriage pads on excavators to prevent 50-ton track penetration.

3.3 Steel-backed (1 mm Q235 + bonded rubber)

• Exposed steel edge wrapped 5 mm with rubber; used for vibrating screen tension plates — bolt torque 300 N·m without slip, solves “flattening and relaxation” of pure rubber plates.

4. Quick selection table (on-site)

5. On-site acceptance — three steps

5.1 Dimensional tolerance

Thickness ±0.2 mm (GB/T 5574-2008 A-grade). Measure four points with micrometer; out-of-tolerance → reject.

5.2 Specific gravity

NBR oil-resistant sheet density 1.35 ± 0.05. If >1.4 → excessive filler loading → oil resistance degraded.

5.3 Hardness

Measure three points with Shore A durometer; average deviation >5 points → reject on site — no need to send to lab.

6. Storage & maintenance

Store flat, out of light, temperature < 25 °C. Do not stack over 1 m high or lower layers deform into a bowl. NR and NBR sheets: re-check hardness every 6 months; if hardness rises by 10 points, scrap — over-vulcanized.

Conclusion & practical rule

Rubber sheets are not “random cutoffs” — they are a three-part material: formulation + vulcanization + reinforcement. Quantify operating temperature, media and mechanical load first, then pick from the table; you’ll reduce on-site rework markedly. Remember: buying a slightly more expensive sheet by ten units is nothing compared to the labor cost of one hour of downtime — you could have bought a whole roll.