Light Cycle Oil (LCO) Storage & Tank Compatibility

Storing Light Cycle Oil (LCO)? Start Here

Light cycle oil (LCO) is a middle-distillate side-stream drawn off a refinery fluid catalytic cracking (FCC) unit, typically distilling in the ~180–370°C range — nominally the diesel boiling window. What sets it apart from a clean diesel cut is its chemistry: LCO is overwhelmingly aromatic, with total aromatic content commonly reported from roughly 70 up to ~80–90 wt.%, and the majority of that is two-ring (di-aromatic / naphthalene-type) species. It also carries high sulfur and nitrogen heteroaromatics and a low cetane number (typically ~30–40), which is why refiners hydrotreat it before using it as a diesel blendstock rather than burning it raw. For storage and transfer the controlling property is that aromaticity. Aromatic hydrocarbons attack polyethylene and polypropylene by absorption-driven swelling and environmental stress cracking, so LCO belongs in steel (or aromatic-rated lined) tankage rather than a plastic vessel. Material selection here is a safety and containment decision, not a cost preference.

Is Light Cycle Oil Compatible With Polyethylene (HDPE / XLPE) Tanks?

No — polyethylene is not recommended for light cycle oil. This one is counterintuitive: LCO boils in the diesel range, and resistance charts rate HDPE as satisfactory for clean diesel, gas oil, and kerosene. But those same charts rate aromatic hydrocarbons and naphtha as unsatisfactory, and LCO is not a clean distillate — it is dominated by di-aromatic (naphthalene-type) species, often 70–90 wt.% total aromatics. Those are precisely the constituents polyethylene cannot hold. Aromatic absorption causes the polymer to swell, soften, lose wall strength, and undergo environmental stress cracking over time — a slow failure that can end in a leak. Cross-linked polyethylene (XLPE) improves stress-crack resistance but does not make the material a barrier to aromatics, so it is likewise unsuitable for sustained LCO service. Store and handle light cycle oil in carbon or stainless steel tankage, or in FRP built with an aromatic-rated vinyl ester or novolac liner, and pair it with FKM (Viton) or fluoropolymer seals. Confirm the final selection against the supplier's SDS and your engineering standards.

Material compatibility at a glance

Light cycle oil is a combustible, highly aromatic middle-distillate petroleum stream, so steel is the default tank MOC — carbon steel (UL-142 / API designs) for ambient bulk storage and stainless where sulfur or temperature warrant it. Polyethylene and polypropylene are unsuitable: the dominant di-aromatic (naphthalene) fraction swells the polymer and promotes stress cracking, unlike a clean diesel cut. FRP is viable only with an aromatic-rated vinyl ester or novolac system. Use FKM (Viton) or fluoropolymer seals and linings; avoid EPDM and natural rubber.

Ratings: S suitable · C conditional / limited · U unsuitable. Verify against the cited resistance charts and your concentration/temperature before specifying.

The safety that actually matters

• Combustible liquid: middle-distillate petroleum oil; keep away from heat, sparks, open flame, and hot surfaces, and bond/ground during transfer. Follow NFPA 30 for storage and avoid static hazards on switch-loading.
• Aspiration hazard (H304): may be fatal if swallowed and drawn into the lungs — do not induce vomiting; seek medical attention.
• Possible carcinogen (representative H350): high-aromatic FCC streams can carry a carcinogenicity classification; minimize skin contact and inhalation. Verify the specific SDS classification.
• Skin and organ effects: causes skin irritation (H315); prolonged or repeated exposure may damage organs (H373). Use chemical-resistant gloves and avoid mists/vapors.
• Environmental hazard (H411): toxic to aquatic life with long-lasting effects — provide secondary containment and prevent release to soil, drains, and waterways.
• Hydrogen sulfide / sulfur species: sour streams may evolve H₂S in headspace; test atmospheres before entry and ventilate enclosed spaces.

Common questions

Can I store light cycle oil in a poly (HDPE or XLPE) tank?

No. LCO is a highly aromatic petroleum oil (often 70–90 wt.% aromatics, mostly di-aromatics), and aromatic hydrocarbons swell polyethylene and cause environmental stress cracking. Use steel (carbon or stainless) tankage, or FRP with an aromatic-rated liner. XLPE improves crack resistance but is still not a barrier to aromatics.

LCO boils in the diesel range — why isn't it OK for poly like diesel?

Boiling range is not the deciding factor; chemistry is. Resistance charts rate clean diesel, gas oil, and kerosene as satisfactory for HDPE, but they rate aromatic hydrocarbons and naphtha as unsatisfactory. Light cycle oil is dominated by di-aromatic (naphthalene-type) species, which puts it in the aromatic category, not the clean-distillate category — so it fails poly even though diesel passes.

What tank material should I use for light cycle oil?

Carbon steel (UL-142 / API designs) is the industry-standard choice for ambient bulk storage; stainless steel is preferred where sulfur species or elevated temperatures are involved. FRP is acceptable only with an aromatic-rated vinyl ester or novolac liner. Pair any of these with FKM (Viton) or fluoropolymer seals.

Is light cycle oil flammable and toxic?

It is a combustible middle distillate (flash point typically in the diesel/gas-oil range, not a low-flash flammable) and carries serious health flags: aspiration hazard, possible carcinogenicity, skin irritation, and aquatic toxicity. Exact NFPA and GHS values are SDS- and stream-dependent, so always work from the supplier's data sheet.