Compliance with the IMO2020 0.5% sulphur cap has driven the introduction of Very Low Sulphur Fuel Oils (VLSFOs). The combustion of VLSFO produces much lower acid concentrations due to reduced Sulphur levels in marine engines as compared to traditional Heavy Fuel Oil. This has required a change in formulation of the engine Lubricating Oil, specifically alkalinity (Base Number or BN). BN protects the engine by neutralising any acids present. Suppliers have recommended ship operators to use 40BN engine oil for use with VLSFOs (rather than 70BN used previously with HFO).
Steve Bee (VPS Group Commercial Director) and Paul Parkinson (VPS Global OCM Business Manager) presented to the marine community over 10 seminars during 2019: "IMO 2020 – Implications, Considerations and Preparations" which highlighted potential BN issues in Cylinder Oil and emphasis was made on the importance of regular monitoring to manage the change and identified the potential negative operational and financial impacts.
As market leaders in marine fuel and lubricants testing and advisory services and, as part of delivering their Oil Condition Monitoring (OCM) and Fuel Quality Testing (FQT) services, Veritas Petroleum Services (VPS) have now been able to conduct a detailed and thorough investigation and report on the impact of VLSFO on cylinder oils since their introduction.
The VPS investigation has identified over 40 vessels suffering major engine damage since starting to bunker VLSFO.
The full white paper is now available on request from VPS and describes in detail;
problems related to excessive liner wear due to abrasion by hard calcium deposits
the potential cause of the deposits from the Lubricating Oil and
suggested measures to prevent engine damage,
Red tinge on piston top with evidence of wear. Image Credit: Ship & Bunker
The investigation identified that the reserve BN in the cylinder oil was not being utilised to neutralise the acids formed during the fuel combustion process. This resulted in calcium compounds being deposited on the piston top, which became hard and abrasive causing liner wear, liner scuffing and piston ring breakage resulting in serious operational issues. See photo (left) showing red tinge on piston top with evidence of wear.
The investigation also identified excessive liner wear on the cylinder units of two‐stroke engines since the introduction of VLSFOs. This damage to engine components has a detrimental impact on vessel operability and has been investigated in this report. Engines affected were not limited to any specific Original Equipment Manufacturer (OEM) but from many of the major engine makers in the marine industry. In all cases VLSFO fuel quality was tested and found to be acceptable and the original cylinder oil that was used was 40BN grade supplied from most of the key suppliers.
The full white paper describes several useful preventative actions that can be taken by ship operators using VLSFOs to help protect engines and avoid costly operational issues arising from excessive liner wear. The VPS Sweep Test can help with a new build, a major overhaul or a fuel type change. On a more routine basis VPS Cylinder Scrape‐Down Analysis (SDA) will regularly allow monitoring of an effective BN formulation.
If you would like to receive the full VPS White Paper, "Engine Protection for VLSFOs" please e‐mail: info@v‐p‐s.com
(*) The investigation utilised the VPS international network, but the key players and authors of this report are:
Stanley George – Marine Engineer, 30 year's experience of marine fuel testing & condition monitoring (P&I Clubs, V‐Ships, Marine Lecturer, sea‐going)
Adrian Allman – Chemist, 30 year's experience of lubricant testing & advice (SGS, Saudi Aramco, Castrol)
Paul Parkinson – Chemist, 25 year's experience of fuel testing & OCM (SGS, Vernolab)