Methyl Soyate (Soy Methyl Ester / B100 Biodiesel) Storage & Tank Compatibility

Storing Methyl Soyate (Soy Methyl Ester / B100 Biodiesel)? Start Here

Methyl soyate — also called soy methyl ester (SME) or B100 biodiesel — is a renewable fatty-acid methyl ester (FAME) made by transesterifying soybean oil with methanol. It is a mixture, not a single pure compound, dominated by methyl esters of linoleic, oleic, palmitic, stearic and linolenic acids (roughly C16–C18 chains). The result is a clear-to-amber oily liquid with a high flash point (>300°F), low VOC content, slow evaporation and strong solvency (Kauri-butanol value near 58).

Industrially it serves two roles: as a drop-in or blend-stock fuel (B100/biodiesel) and as a low-toxicity bio-solvent in parts cleaners, degreasers, paint and graffiti removers, adhesive removers, and agricultural adjuvant/carrier formulations. Because it behaves like a light petroleum oil toward plastics — permeating and swelling standard polyethylene — material of construction selection is critical to avoid tank weight gain, softening and seepage over a storage cycle.

Is Methyl Soyate Compatible with Polyethylene (HDPE / XLPE) Tanks?

No — standard polyethylene is not recommended for long-term storage of methyl soyate / B100 biodiesel. As an oily fatty-acid methyl ester, methyl soyate is absorbed by the polyethylene matrix: immersion studies of HDPE in B100 show measurable mass gain and swelling, and biodiesel handling guidance specifically advises against ordinary polyethylene for long-term B100 storage. Over a storage cycle this can soften walls, distort fittings and lead to seepage.

For methyl soyate, choose steel, stainless steel, aluminum, or a fiberglass/FRP tank built with a biodiesel-rated resin, and use Viton (FKM) seals rather than nitrile or EPDM. Fluorinated polyethylene is a conditional improvement over untreated poly, but the fluorination level must be matched to the service. If a tank's compatibility chart is silent on FAME/biodiesel/methyl esters, treat polyethylene as unsuitable until the manufacturer confirms otherwise in writing.

Material compatibility at a glance

Methyl soyate is an oily, petroleum-class fatty ester (biodiesel/bio-solvent). The dominant compatibility driver is its solvent/permeant behavior toward polymers, not pH or oxidation. Store and convey in steel, stainless steel, aluminum, or biodiesel-rated FRP with Viton (FKM) seals. Standard HDPE/XLPE polyethylene is unsuitable for long-term storage because the ester permeates and swells the resin; fluorinated polyethylene is a conditional step up but verify the fluorination level for your service.

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: high flash point (>300°F) means it is not easily ignited, but it will burn — keep away from open flame, sparks and hot surfaces.
• Low acute toxicity and biodegradable, yet still a fuel/oil — avoid ingestion and prolonged skin contact; wear chemical-resistant gloves and eye protection.
• Oil-soaked rags and absorbents can self-heat; dispose of in closed metal containers to reduce spontaneous-combustion risk.
• Spills create slip hazards and are oily/persistent — contain and use oil-type absorbents; prevent entry to drains and waterways.
• Strong solvent action can swell or degrade incompatible plastics and elastomers — verify hoses, seals and tank resin before use.
• Hazard classification is representative and SDS-dependent — always follow the specific supplier Safety Data Sheet for your grade and blend.

Common questions

Can I store methyl soyate or B100 biodiesel in a standard HDPE poly tank?

Not for long-term storage. Methyl soyate is an oily fatty ester that permeates and swells standard HDPE/XLPE, causing measurable mass gain and potential softening. Use steel, stainless, aluminum, or biodiesel-rated FRP, with Viton (FKM) seals. Fluorinated polyethylene is a conditional step up — confirm the fluorination level with the manufacturer.

Is methyl soyate flammable?

It is classified as combustible rather than flammable. Its flash point is above 300°F (over 150°C), so it is far harder to ignite than gasoline or diesel, but it will still burn. Keep it away from ignition sources and store oil-soaked rags in closed metal containers.

What is methyl soyate made of?

It is a mixture of methyl esters of soybean-oil fatty acids — predominantly methyl linoleate, methyl oleate, and saturated C16–C18 esters (palmitate/stearate), with some methyl linolenate. It is produced by transesterifying soybean oil with methanol, so it is a formulation, not a single pure compound.

What seals and gaskets work with methyl soyate?

Viton (FKM) is the preferred elastomer for biodiesel/FAME service. Nitrile (Buna-N) and EPDM tend to swell and degrade and should be avoided. Always confirm hose, seal and pump materials against the product SDS and the equipment manufacturer's biodiesel compatibility data.