Extended Operational and Trade Vocabulary

Marine Fuel Quality and ISO 8217 glossary (page 2)

The fuel-quality vocabulary anchored in ISO 8217: abrasive wear from catalyst fines, accelerated and aged total sediment (ISO 10307-2), total acid number, additive treatment, and the stability and ignition parameters that grade a residual or distillate. Grounds each term in the ISO test method and the specification limit it reports.

321 defined terms.

Showing 71 on this page (page 2 of 2).

R

RMD 80: Residual grade with maximum viscosity 80 cSt at 50 C.
RME 180: Residual grade with maximum viscosity 180 cSt at 50 C, low residue.
RMG 180: Residual grade with maximum viscosity 180 cSt at 50 C.
RMG 380: Residual grade with maximum viscosity 380 cSt at 50 C, the workhorse pre-2020 HSFO.
RMG 500: Residual grade with maximum viscosity 500 cSt at 50 C.
RMG 700: Residual grade with maximum viscosity 700 cSt at 50 C.
RMK 380: Higher-density residual grade, max density 1010 kg/m3 at 15 C.
RMK 500: RMK grade at 500 cSt nominal viscosity.
RMK 700: RMK grade at 700 cSt nominal viscosity.
Rotational viscometer: Laboratory viscometer of cone-and-plate or concentric cylinder type used for residual fuels at process temperature.

S

Salt water contamination: Sodium-rich water ingress, detectable by elevated sodium relative to vanadium and by chloride testing.
Sample bottle: Compliant glass or amber HDPE container for bunker samples, sealed with tamper-evident closure and uniquely numbered.
Sample seal: Tamper-evident seal applied to bunker samples with unique numbering.
Sampling cubitainer: Collapsible plastic container used by some sampling services for transport of bunker samples.
Saybolt fuel testing: Bunker quality testing service within the Core Lab / Saybolt network operating worldwide.
Scrubber-compatible fuel: Residual fuel above the 0.50 percent sulfur cap whose use is permitted on ships fitted with an approved exhaust gas cleaning system.
SECA: Sulphur Emission Control Area, terminology superseded by ECA.
Sediment: Solid material suspended in or precipitated from fuel, measured by ISO 10307 or ASTM D4870.
Self-cleaning separator: Centrifugal separator with intermittent automatic discharge of accumulated sludge from the bowl periphery.
Service tank: Settled and purified fuel tank ready for use, also called day tank.
Settling tank: Heated tank that allows water and solids to fall out before centrifuging.
Sodium: Element in fuel acting alongside vanadium to cause high-temperature corrosion.
SOLAS Reg II-2/4: Convention provision requiring minimum 60 C flash point for fuel oil used on cargo ships, with limited 43 C exception for emergency systems.
Soot blower: Steam/air blower for boiler tube cleaning.
Sounding pipe: Vertical pipe with screwed cap allowing tape sounding of tanks.
Spot test: Compatibility test on filter paper per ASTM D4740.
Stability: Ability of a residual fuel to remain homogeneous without asphaltene precipitation.
Stability reserve: Margin between current asphaltene peptization state and the onset of precipitation, quantified by P-value or similar indices.
Standard reference fuel: Calibration fuel of certified composition used to verify cetane engine, viscometer, or density meter performance.
Sulfated ash: Inorganic residue measured after ashing with sulfuric acid, relevant to lubricants more than fuels.
Sulfur cap: Regulatory upper limit on fuel sulfur content, 0.50 percent globally and 0.10 percent in SECAs under MARPOL Annex VI.
Sulfur content: Mass fraction of sulfur in fuel, measured by ISO 8754, ISO 14596, ISO 20846, ISO 20884, or ASTM D2622/D4294.
Surface tension: Property influencing droplet formation at injection, indirectly affecting combustion of poor-quality residual fuel.

T

TAN: See total acid number.
Tank stripping: Removal of last residues from a bunker tank, often containing concentrated water and sediment.
Tank table: Calibrated relationship between ullage and volume for each ship or barge tank.
Test method: Documented analytical procedure such as those issued by ISO, ASTM, or the Energy Institute.
Thermal stability: Resistance of fuel to chemical change on heating in the fuel system upstream of injection.
Toluene equivalence: Aromaticity reference scale used in some compatibility procedures.
Total acid number (TAN): Milligrams of potassium hydroxide required to neutralize the acids in one gram of fuel, measured by ASTM D664 or IP 575.
Total existent sediment: Sediment measured by ISO 10307-1 without aging.
Total potential sediment (TSP): Combination of existent and accelerated sediment, used historically; superseded operationally by TSA.
Total sediment accelerated (TSA): Sediment measured after thermal aging per ISO 10307-2 Procedure A, capped at 0.10 percent mass in ISO 8217 RM grades.
Trace metals: Vanadium, sodium, aluminum, silicon, iron, nickel, calcium, zinc, phosphorus, and others reported on bunker analysis certificates.
Trimming: Adjusting ship's draft and list before bunker survey to allow accurate sounding of all tanks.

U

Ullage: Empty space above liquid cargo in a tank.
Ultra low sulfur fuel oil (ULSFO): Residual or hybrid fuel with sulfur content at or below 0.10 percent for SECA compliance.
Ultraviolet fluorescence: Sulfur analysis principle used in ISO 20846 method.
Unstable fuel: Residual fuel whose asphaltene phase has separated or is at risk of separating, evidenced by elevated TSA and poor spot test rating.
Used lubricating oil (ULO): Spent crankcase oil, prohibited as a bunker blendstock by ISO 8217 due to metals and combustion behavior.

V

Vanadium: Trace metal in residual fuel; combines with sodium to cause high-temperature corrosion in turbines.
Vanadium to sodium ratio: Indicator of hot corrosion risk, traditionally targeted at three to one or higher.
Vapor pressure: Pressure exerted by fuel vapors at a given temperature, relevant for methanol and LNG.
Very low sulfur fuel oil (VLSFO): Residual fuel oil with sulfur content at or below 0.50 percent for IMO 2020 compliance outside SECA waters.
Viscosity at 100 C: Property reported for very heavy residues alongside the 50 C value.
Viscosity blending index: Logarithmic transformation enabling linear blending calculations for kinematic viscosity.
Viscosity index: Measure of viscosity change with temperature, more relevant to lubricants than fuels.
Viscotherm: Trade designation for a class of in-line marine viscometers and viscosity control fuel heaters.
Volume correction factor: Multiplier applied to observed volume to convert to standard temperature, drawn from ASTM/IP tables 54B/54D for bunker fuels.
VPS: Veritas Petroleum Services, marine fuel testing and inspection company operating under the DNV group.

W

Wartsila changeover automation: Engine maker procedure for managed switch between residual and distillate grades in two-stroke and four-stroke engines.
Water and sediment: Combined contaminant fraction reported by some test methods, distinguished from individual water and sediment limits in ISO 8217.
Water by distillation: Volumetric water determination per ISO 3733, the routine bunker test.
Water content: Free and emulsified water in fuel, limited to 0.50% V/V in most residual grades.
Wax appearance: Onset of wax crystallization in distillate fuel, related to cloud point and CFPP.
Westfalia GEA: See GEA Westfalia.
Wettability: Surface property influencing water dispersion in fuel and effectiveness of demulsifiers.
Wheel sampler: Continuous drip sampler using a rotating wheel to take a constant fraction of the bunker stream.

X

X-ray fluorescence (XRF): Spectroscopic technique used for sulfur and trace metal determination per ISO 8754, ISO 14596, and related methods.

Z

Zinc: Element in some lube oils from ZDDP additive; absence indicates an ashless or low-ash formulation.
Zone refining: Laboratory crystallization technique unrelated to bunker practice but cited occasionally in fuel research contexts.