# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/DdaKX1mxbOC
- **Gondola URL:** https://gondola.cc/posts/70577840-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/cd3a799946.jpg
- **Posted:** 2026-09-18T00:36:39.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

Most of what you own crossed an ocean burning a fuel that will not pour at room temperature.

Heavy fuel oil, sold as bunker C or IFO 380, is the residue left after a refinery has stripped out petrol, kerosene and diesel. At 20°C it behaves closer to cold asphalt than to a liquid, and pour points run as high as 30°C, so an unheated tank sets into a waxy, asphaltene-rich solid.

What that forces on the ship:

- Viscosity is specified at 380 centistokes at 50°C. Water sits near 1 cSt, and injectors need 10 to 15 cSt to atomise cleanly
- Bunker tanks are steam-traced to roughly 40-50°C simply to be pumpable, then trimmed to 120-150°C at the final heater before injection
- Density reaches 991 kg/m³, dense enough to sink in seawater, so a heavy fuel spill sludges the seabed rather than floating for skimming
- Lower heating value sits near 40 MJ/kg against 42.7 for marine gas oil, yet the density advantage puts it ahead volumetrically at close to 40 GJ/m³

The reason shipping tolerates all of this sits in the crankcase. Low-speed two-stroke crosshead diesels are the most thermally efficient production heat engines ever built: roughly 50 per cent brake thermal efficiency, above 54 per cent with waste heat recovery, turning at 80 to 100 rpm with bores approaching a metre and strokes of 2.5 metres. Slow, enormous and tolerant enough to digest residue that would destroy a road engine within hours.

And the residue is hostile. ISO 8217 permits up to 350 mg/kg vanadium and 60 mg/kg of catalyst fines, aluminium-silicon particles carried over from fluid catalytic cracking and hard enough to score a cylinder liner. Centrifugal purifiers spin them out onboard before the fuel reaches an injector. Sulphur ran to 3.5 per cent by mass, some 35,000 ppm, until the IMO capped it at 0.50 per cent in 2020.

The bottom of the barrel moves over eighty per cent of world trade by volume.

#stemantics #marineengineering #thermodynamics #materialsscience #engineering

## Stats

- **Views:** 121,999
- **Likes:** 740
- **Shares:** 0
- **Comments:** 34

## Tags

marineengineering, engineering, materialsscience, thermodynamics, stemantics

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