Class 1 (Chief Engineer) Engineering Management 📅 Oct 2019

Exam Question

To operate engines in compliance with the new IMO 2020 sulphur limits and to prepare the engine and auxiliaries for the changes in fuel characteristics, is a challenge for owners, operators and crews. From the Chief Engineer's perspective explain the following briefly:

(a) Cylinder lubrication strategies.

(b) Compatibility issues between fuel bunkered at different ports.

Reference Answer

As a Chief Engineer, ensuring compliance with IMO 2020 sulphur limits while maintaining engine reliability requires a multifaceted approach. The challenges presented by new Very Low Sulphur Fuel Oils (VLSFO) and the transition from traditional High Sulphur Fuel Oil (HSFO) necessitate robust strategies in lubrication, fuel handling, and system preparation.
### (a) Cylinder Lubrication Strategies
The shift to low sulphur fuels ( 1.5% S):** Requires high-BN cylinder oils (e.g., 70-100 BN) to neutralize the large quantities of sulphuric acid (H₂SO₄) formed during combustion. This prevents cold corrosion of the cylinder liner.
* **Low Sulphur Fuel (<0.50% S):** Requires low-BN cylinder oils (e.g., 15-40 BN). Using a high-BN oil with low sulphur fuel leads to an excess of un-neutralized alkaline additives (calcium carbonate). These compounds form hard, abrasive deposits on piston crowns and in ring grooves, leading to bore polishing, ring sticking, and catastrophic scuffing.

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