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Cylinder condition monitoring for two-stroke engines

Know the condition of every cylinder without lifting a piston.

Flame Diagnostic reads the fuel system, engine performance, and cylinder oil and condition together, and reports unit by unit what is happening inside your two-stroke engines and what to do about it. Your technical department in one report.

Flame SDA covers the engine designers' recommended scavenge drain (scrape-down) oil reporting at low cost, and delivers much more than a laboratory sheet.

Talk to us about your fleet How it works
  • Drain oil analysis since 1998
  • Independent, and trusted by ship managers and engine designers
  • First to understand and use dilution and contamination correction in drain oil sampling
  • Analysis used by an engine designer in its own development testing

Early warning

Wear, deposits, blow-by and water usually show in the drain oil before they show in performance data or at a port inspection.

Overhaul by condition

Open the units that need it, when they need it, and let the others run on with evidence to support the decision.

The right feed rate and BN

Cylinder oil brought to the lowest safe feed rate for the fuel in use, with less waste drain oil to dispose of.

The designers' recommendation met

Accredited laboratory analysis at the intervals the engine designers specify, with the interpretation a laboratory sheet does not provide.

Flame SDA and Flame Diagnostic

Two reports

Both use the same accredited laboratory and the same dilution correction. They differ in what goes in and how far the reading goes.

Flame SDA

The engine designers' recommended scrape-down oil reporting, and much more than a laboratory sheet.

  • Tested in an ISO/IEC 17025-accredited laboratory to ASTM, ISO and IP methods
  • Evidence-based insights, corrected for dilution
  • Practical lubrication guidance
  • Optional fuel purifier and service tank check: cat fines and water
  • Built on more than 25 years of Flame Diagnostic data
  • At low cost

About Flame SDA

Flame Diagnostic

A comprehensive report covering the fuel system, engine performance, and cylinder oil and condition. Your technical department in one report.

  • Everything in Flame SDA, plus:
  • Correlation between fuel, lubrication and performance
  • Fuel purifier and separator performance, and fuel system integrity, verified
  • Detailed advice and recommendations across the engine

About Flame Diagnostic

Independence

Independent

Flame Marine has been an independent provider of engine performance and oil analysis services since 1998, and its papers published by CIMAC, some of them jointly with an engine designer, have helped shape the role of scavenge drain analysis. Most scavenge drain oil analysis is offered by lubricant suppliers as part of their service. Flame Marine supplies no lubricant and sells no fuel, so its advice on feed rate and BN has no commercial interest in the quantity or grade of oil consumed. The samples go to an accredited laboratory with no stake in the result.

Dilution

Every drain oil sample is a mixture

Scavenge drain oil is used cylinder oil mixed with system oil from the stuffing box, unburned fuel and water. Read as if it were pure cylinder oil, it understates wear and overstates the loss of BN. Flame Marine was the first to understand and use dilution and contamination correction in drain oil sampling: every figure in a Flame report is corrected, using Flame ADT, before it is analysed.

One sample, two readings A scavenge drain oil sample made up of 60 percent used cylinder oil, 38 percent system oil and 2 percent fuel and water. As measured, iron is 95 milligrams per kilogram and residual BN is 50 percent of fresh. Corrected to a cylinder-oil basis with Flame ADT, iron is 158 and residual BN is 78 percent. What is in the sample Used cylinder oil 60% System oil 38%, past the stuffing box Fuel and water 2% Iron, total (mg/kg) As measured 95 Corrected with Flame ADT 158 Residual BN (% of fresh) As measured 50% Corrected with Flame ADT 78% As measured: wear normal, BN low. Corrected: wear rising, BN adequate.
Illustration with example figures: cylinder oil BN 70, system oil BN 6, a sample that is 60% used cylinder oil by mass.

Dilution and Flame ADT

Guidance

Specified by the engine designers

Flame reports cover the three two-stroke designs in service: MAN B&W (Everllence), WinGD and UE (Japan Engine Corporation, formerly Mitsubishi). The major designers now specify regular laboratory analysis of scavenge drain oil. The samples have to be taken. The value is in how they are read.

Everllence (formerly MAN Energy Solutions)
Service Letter SL2023-738, scavenge drain oil analysis

Analysis by an accredited laboratory at least every three months or 1,500 running hours, alongside monthly inspection through the scavenge ports. Total and magnetic iron, read against limits that depend on fuel sulphur and corrected for feed rate, and residual BN against the fresh cylinder oil.

WinGD
Lubricants Guideline DTAA001621

Regular analysis of residual BN and iron for each cylinder, repeated after any change of feed rate, fuel or cylinder oil, with laboratory results as the reference for feed rate and BN decisions.

UE engines are sampled and reported on the same basis. Summaries for orientation; always refer to the current issue of the designer's guidance for your engine.

Inside a report

What the report tells you

A laboratory sheet gives you iron and BN. A Flame report reads them, corrected, with the engine's history and tells you what they mean for each cylinder.

The assessment panel of a Flame SDA report: ten cylinder conditions assessed for each of twelve cylinders with green, amber and red markers and a one-line finding per row, then the system oil and the fuel samples
Extract from a Flame SDA report: the assessment. One row per condition, one marker per cylinder, and the finding in words; the system oil and the fuel samples below.Within limits Attention Action required

Beyond the assessment

The report also carries the analysis results for every cylinder, corrected for contamination and dilution, plotted against the engine designer's zones for iron and BN, within limits, warning and alert, and trended against the vessel's earlier samples. Flame Diagnostic adds combustion and injection, feed rate and BN set against the performance data as well as the drain oil, fuel treatment on board, and the engine parameters kept for the technical file.

Every finding is cross-checked against the others. A reported Pmax that does not fit the combustion picture is questioned, not passed on.

Inside a Flame Diagnostic report

In the engine

What the drain oil sees first

By the time a problem is visible at a port inspection or in the performance data, its chemistry has been in the drain oil for some time.

Cylinder liner with a horizontal crack shown by red dye penetrant on white developer
Liner crack, found by dye penetrant A crack that reaches the cooling space lets water into the cylinder. Water in one unit's drain oil, and not in the others, is an early warning.
Piston removed from the engine, with thick grey ash deposits on the crown and top land
Crown and top-land deposits Largely ash from cylinder oil the unit did not need. Residual BN in the drain oil shows when the feed rate or the oil's BN is higher than the fuel sulphur calls for.
Hard pale deposit band on the top land of a piston above the ring pack
Hard deposit on the top land Deposits like this rub the liner and polish away the honing that holds the oil film. The trend in iron shows the wear it causes.
Open scavenge air box door with the piston ring pack and skirt visible inside
Through the scavenge air box door A port inspection shows the ring pack and skirt as they are that day. The drain oil shows what is happening to them between inspections.
Where the samples and readings come from Simplified section of a two-stroke crosshead engine cylinder. Samples sent to the laboratory: fuel, scavenge drain oil from every cylinder, and system oil. Readings taken at the same time: cylinder pressures and scavenge air. Cylinder pressures Pmax and compression, each unit Fuel From points in the fuel system Scavenge air Pressure and temperature Scavenge drain oil From every cylinder System oil From the crankcase system
Sample sent to the laboratory Reading taken at the same time

How it works

From sample to report

Nothing is tested on board and the engine is never stopped for it.

  1. Samples and readings, taken together

    The crew draw scavenge drain oil from every cylinder, samples of the fresh cylinder oil and the system oil, and fuel samples, and record the performance data at the same time.

  2. Accredited laboratory analysis

    The samples go by courier to the laboratory: iron, total and magnetic, wear metals, residual BN, water, contaminants and additive elements.

  3. Interpretation, unit by unit

    The results are read with the performance data and the engine's history, and the report sets out findings and recommendations for each unit.

How the service works in detail

For service providers

Flame Diagnostic also runs behind condition monitoring services that other organisations deliver under their own names.

Working with service providers

Talk to us about your fleet

Tell us the engine types and the number of vessels, and we will come back to you with how sampling would work for you and what the reports would cover.

Contact details