Rc-70 Cutback Storage
Last updated: 2026-10-19
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RC-70 Cutback Storage: Direct Answer
RC-70 cutback asphalt (formerly RT-7, per ASTM D-2028) should be stored in vented steel tanks at 10–40°C (50–104°F), kept below 50°C, with nitrogen blanketing or vapor-space ventilation, and rotated within 6–12 months of manufacture. Open-flame exposure must be prevented below 60°C flash point range, and storage losses from evaporation typically run 0.5–2% per month in unsealed tanks.
What RC-70 Cutback Actually Is (and Why Storage Differs from Emulsion or Penetration-Grade Bitumen)
RC-70 is a rapid-curing (RC) cutback bitumen: penetration-grade bitumen fluxed with a volatile petroleum solvent (typically naphtha/gasoline-range distillate with ≈45–55% aromatics). The "70" refers to kinematic viscosity of 70 cSt at 60°C.
Key storage implications:
- Solvent volatility: unlike penetration-grade bitumen, RC-70 loses light fractions on exposure to air → viscosity rise, hardening, and flash-point shift.
- Flash point: typically ~27–40°C (80–105°F) depending on solvent, making RC-70 a flammable liquid (Class II/III per NFPA) — not a simple hot-storage product.
- Oxidation resistance: less critical than volatility, but skinning and gum formation occur above 45–50°C in vented tanks.
| Property | RC-70 (typ.) | Pen 70/100 Bitumen | CRS-2 Emulsion |
|---|---|---|---|
| Storage temp | 10–40°C | 140–160°C | 10–50°C |
| Volatility loss | 0.5–2%/month (open) | Negligible | ~0.1%/month |
| Flash point | 27–40°C | >230°C | Non-flammable (water) |
| Shelf rotation | 6–12 months | 2–5 years | 3–6 months (settling) |
| Tank type | Vented, grounded steel | Insulated hot tank | Agitated, mild steel |
Storage Conditions: Temperature, Ventilation, and Tank Design
Temperature. Store at 10–40°C ambient; never exceed 50°C (solvent loss accelerates exponentially, and fire risk rises sharply). Heating should be slow and indirect only where viscosity demands it — most applications use the material at ambient or 30–45°C pumping temperature. Never use steam coils above 60°C surface temperature.
Tank design checklist:
- Vented, grounded carbon-steel tanks with flame arresters on vents.
- Nitrogen blanketing (0.3–0.7 bar) reduces solvent loss to <0.3%/month versus 1–2% open.
- Fixed roof or internal floating roof; avoid open-top drums for >30 days.
- Transfer pipelines sized for viscosity at 20–30°C (70–150 cSt at operating temp), with line flushing schedule.
- Bunding/secondary containment: RC-70 is a Class II flammable liquid; containment volume ≥110% of largest tank.
- Segregation: no oxidizers, no open flames within 15 m, no smoking, bonded/grounded transfer.
| Storage configuration | Solvent loss/month | Recommended max hold |
|---|---|---|
| Open drum (240°C ambient) | 1.5–2.5% | 30 days |
| Fixed-roof tank, vented | 1.0–2.0% | 6 months |
| Nitrogen-blanketed tank | 0.2–0.5% | 12–18 months |
| Tank with recirculation + N₂ | 0.2–0.3% | 18 months |
Shelf Life, Degradation Signals, and Re-Testing Schedule
Typical shelf life: 6–12 months in compliant storage; up to 18 months with nitrogen blanketing and quarterly recirculation.
Degradation signals (test quarterly):
- Kinematic viscosity (60°C): drift >10% from 70 cSt → flag.
- Flash point: drop below 27°C → reclassify, review fire safety.
- Residue after distillation: change >5% → blending quality issue.
- Skinning/gum in tank bottoms: re-circulate or blend; do not store >24 months.
| Test | Frequency | Limit (RC-70) | Trigger |
|---|---|---|---|
| Viscosity @60°C | Quarterly | 70 cSt ±10% | >15% drift → blend/reclassify |
| Flash point | Quarterly | ≥27–40°C | <27°C → safety review |
| Solvent content | Quarterly | ~55–65% distillate | Change >5% → adjust blend |
| Water content | Monthly | <0.5% | Settling/emulsion concern |
Cost, Logistics, and Buying Decisions (with 6Tar Data Points)
Storage cost is driven by tank rental or build, nitrogen cost (~$0.50–1.50/m³), and rotation frequency. For a 20-tonne batch stored 6 months in a nitrogen-blanketed tank, typical handling/storage overhead adds 1.5–3% to landed cost. RC-70 pricing varies with solvent and crude; for current per-tonne and per-drum figures, use the ranking on the 6Tar site's bitumen price pages rather than historical snapshots (FOB levels fluctuate monthly).
| Cost factor | Typical range | Notes |
|---|---|---|
| Tank rental | $300–800/month (100–200 t tanks) | Regional variance |
| Nitrogen blanketing | $0.50–1.50/m³ | ~0.3 bar pressure |
| Evaporation losses | 0.5–2% of tonnage/year | 100 t → 0.5–2 t/yr |
| Recirculation energy | $150–400/month | Pumps, lines |
| Re-testing (lab) | $120–250 per sample | Viscosity, flash, water |
Bulk vs. drum comparison:
| Scenario | Bulk tank (50 t) | Drums (50 t, 200 × 200 L) |
|---|---|---|
| Storage loss/year | 0.5–1% | 2–3% (unless sealed) |
| Handling cost | Low | Medium–High |
| Shelf life | 12–18 months | 6–9 months |
| Re-test cost | Low (batched) | Higher |
FAQ: RC-70 Cutback Storage
Q1: How long can RC-70 cutback be stored?
A: In a vented, grounded steel tank below 40°C, 6–12 months. With nitrogen blanketing and quarterly recirculation, up to 18 months with viscosity drift under 10%.
Q2: What temperature should RC-70 be stored and handled at?
A: Store at 10–40°C; never exceed 50°C. Pump at 20–45°C to keep viscosity manageable — heating above 60°C risks flash-point ignition and rapid solvent loss.
Q3: Can RC-70 be stored in drums or IBC totes?
A: Only for ≤30–60 days, in sealed, grounded drums away from flame and direct sun; expect 1.5–2.5%/month solvent loss. For anything longer, use a nitrogen-blanketed tank.
Q4: How do I know if stored RC-70 has degraded?
A: Test viscosity at 60°C (flag if >10% drift from 70 cSt), flash point (flag if <27°C), and water content (<0.5%). Skinning or thickening signals solvent loss or oxidation — recirculate or blend before use.
Q5: How much does RC-70 cutback storage cost?
A: For a 50-tonne bulk tank, expect $300–800/month tank rental, ~$0.50–1.50/m³ nitrogen, and 0.5–2% annual tonnage loss. Total storage overhead typically lands at 1.5–3% of landed product cost.
CTA: Run Your Storage Costs on the 6Tar Cost Calculator
Before you book tank space or place a 50-tonne order, run the numbers on the 6Tar cost calculator. Enter your tonnage, tank size, storage duration, and nitrogen-blanketing assumption to get a per-tonne landed cost including storage losses, then compare it directly against bulk and drum options — so your RC-70 sits in compliant storage at the lowest verified cost.