Two stroke engines lubrication presentation with software solution. Presentation was made in 2014 promoting the software solution for engines lubricated by older version of lubrication systems. The principle idea was to speed up the calculations and reduce the risk of maladjustment of the oil dose.

1. SCOCCAL calculator
Specific Cylinder Oil consumption calculator for Wartsila
RTA family engines.
By M. A. Wilkolek I.Eng., MRINA, MIMarEST

2.  The reasons for lubrication of two stroke engines’ liners
 Reduce friction
 Remove the heat
 Clean running surface
 Sulphur acid neutralization
 Disperse of dirt and sludge
Liners lubrication
M. A. Wilkolek 2014

3. M. A. Wilkolek 2014
The cracked liner from
6RTA62 U engine. The liner
split during removing from
engine.
The condition of
engine we like to
avoid.

4. M. A. Wilkolek 2014
The scuffed liner in top part
displays lubrication problem.
The condition of
engine we like to
avoid.
Excessive sludge immobilized piston
rings casing theirs breakdown.

5. M. A. Wilkolek 2014
Corroded liner wall.
The condition of
engine we like to
avoid.

6. M. A. Wilkolek 2014
The completely closed „graphite
flakes” structure of liner wall.
The condition of
engine we like to
avoid.

7. M. A. Wilkolek 2014
Healthy liner wall structure with clearly
visible „graphite flakes” in ferrite matrix.
This structure provides good cylinder oil
distribution and ensure prolonged
lifetime.
The condition we
would like to
achieve.
Properly lubricated piston rings.

8.  Hydrodynamic lubrication
 Mixed film lubrication
 Boundary lubrication
 Van der Waals adsorption
 High viscosity layer formation
 Thin reacted layer and smoothing
 Thick reacted inorganic layer
Tribology - lubrication
Roughness of surfaces is a
critical factor during the
boundary lubrication.
M. A. Wilkolek 2014

9.  Adhesive wear as result of direct contact of two
metals also known as cold welding.
 Abrasive wear in presence of foreign material or as
consequence of adhesive wear.
 Contact fatigue – when excessive forces acting on
working surfaces are applied.
 Corrosive wear – covers all aggressive chemical
reactions acting on metals.
Tribology - wear
M. A. Wilkolek 2014

10.  Viscosity - absolute and kinematic viscosity
 VI – viscosity index gives quick reference for oil
behavior under different temperatures
 Additives to enhance lubricating oil properties for
specific purpose:
 Antioxidants
 Detergents
 Dispersants
Tribology - properties of lubricants
M. A. Wilkolek 2014

11. M. A. Wilkolek 2014
Pressure distribution across piston ring height acting on „barrel shape” ring.
So called lifting effect uses lubricating oil viscosity to separate piston
ring from liner wall.
The liner – piston ring sealing effect is generated by combustion gases acting
on inner side of piston ring and pressing the ring toward the liner.

12.  Total Base Number – chemical property describing
ability of acid neutralization.
 Acidity exists naturally in mineral oils and must be
compensated by presents of alkalinity.
 Acidity is also added via fuel in to combustion
chamber – it must be neutralized.
M. A. Wilkolek 2014
TBN – minimum lubrication required

13.  Only 1% of SOx is contributing in sulphuric acid
creation
 Not all of 1% will condensate on cylinder liner’s wall
 The basic chemical reactions:
 2S + 3O2 → 2SO3
 2SO3 + 2H2O → 2H2SO4
 2H2SO4 + 2CaCO3 → 2CaSO4 + 2H2O + 2CO2
M. A. Wilkolek 2014
TBN – minimum lubrication required

14.  Absolute minimum 0.5-0.55 g/kWh.
 Above 1.6 g/kWh high wear risk of piston rings
breakage
 Under dosing – oil starvation and boundary
lubrication
 Overdosing – excessive slugging and piston rings
immobilization
Liner wear vs. lubrication dosage
M. A. Wilkolek 2014

15. Liner wear vs. lubrication dosage
0 0,2 0,4 0,6 0,8 1 1,2 1,4 1,6 1,8
0
0,2
0,4
0,6
0,8
1
1,2
0
0,2
0,4
0,6
0,8
1
1,2
0 0,5 1 1,5 2 2,5
Cylinder oil dosage [g/hbph]
Wear[mm/1000h]
Cylinder oil dosage [g/kWh]
M. A. Wilkolek 2014

16.  Run-in program
 Minimizing consumption without breaking down
engine
 Maximizing lifetime of liners
 Avoid unnecessary vessels delays and engine
immobilization
 All together means reduction and control of
operation costs.
Why do we control lubrication?
M. A. Wilkolek 2014

17. Why the program?
Traditional calculations
M. A. Wilkolek 2014
According to maker instruction each
time the lubrication is to be changed
this diagram must be use. The SCOC
calculation is slow and ineffective. The
lubrication setting for running-in
program consumes considerable
amount of time. Precision is subject of
diagram condition and size.

18. The program is a decision support tool for ship’s crew. It
provides quick calculations for Specific Cylinder Oil
Consumption under different conditions.
The SCOC can be calculated for different load condition
for each unit separately.
The best combination of disk - frequency converter or,
in older models, adjusting screw - pin position setting
can be easily tested.
The program
M. A. Wilkolek 2014

19. The program. Configurator.
M. A. Wilkolek 2014
The configurator module
let the user to set-up all
basic information about
engine and the lubricating
system’s configuration.
The information entered
here is stored in
configuration file which is
loaded during start of
program.

20. The program. Calculations.
M. A. Wilkolek 2014
The main module consist
of basic and advanced
calculations parts. In the
basic part the SCOC is
calculated for MCR using
the „speed factor” as a
base for calculation no
additional data is
required.

21. The program. Calculations.
M. A. Wilkolek 2014
The advanced calculations
allow user to check
different combinations of
input parameters.
Example:
The different load across
the engine can be the
reason for different SCOC
per unit.
Optional method for
calculation based on
Service Bulletin RTA-76.

22. Thank you for attention