While Mass Flow Meters have significantly improved transparency and accuracy in bunker deliveries, experience shows that they are not immune to misuse, writes Alvin Forster, Senior Loss Prevention Executive – Americas & UK, NorthStandard.
Bunker quantity disputes remain one of the most frequent and contentious causes of claims and charterparty disputes. Traditional measurement methods based on tank soundings, ullage measurements, and calibration/sounding tables have long been criticised for their susceptibility to error and manipulation. In response, several major bunkering ports have mandated the use of Mass Flow Meters (MFMs) as the primary means of measuring the quantity transferred.
MFMs have significantly improved transparency and accuracy, but experience has shown that they are not immune to misuse or deliberate manipulation. Recent enforcement actions, most notably in Singapore, demonstrate that unscrupulous suppliers may still attempt to defeat even sophisticated measurement systems.
The Evolution of Mass Flow Meters Mandates
Singapore pioneered the mandatory use of MFMs. Since 1 January 2017, MFMs have been compulsory for the delivery of marine fuel oil in the Port of Singapore, with the delivered quantity on the Bunker Delivery Note (BDN) derived exclusively from the MFM totaliser.
The regime has continued to evolve. From 1 April 2025, Singapore mandated compliance with SS 648:2024, which tightens requirements around data security, system integrity, piping arrangements, certification, and the use of data loggers and edge devices, reflecting lessons learned from earlier enforcement cases.
Mass Appeal for MFMs
From 1 January 2026, MFMs were also made mandatory on bunker vessels delivering fuel oil, diesel, and biofuels at the ports of Rotterdam and Antwerp‑Bruges. The systems must be certified and broadly aligned with ISO 22192, mirroring the Singapore model. The use of MFMs is also mandatory across port terminals in Türkiye and at the Port of Ceuta in the Gibraltar Strait, while they are actively used in Gibraltar by yacht bunker supplier CEPSA and others.
These developments signal a significant shift in the European bunker market, which has traditionally been reliant on shore tank measurements and barge gauging.
Elsewhere, Sohar Port and Freezone have introduced measures that effectively mandate the use of MFMs for bunker supplies. Hong Kong is also looking to introduce regulations that mandate their use, but exclusively for methanol. Further afield, an increasing number of suppliers are adopting the use of MFMs in ports and hubs where no formal mandate exists. Locations where MFMs are currently used on a non-mandatory basis include Fujairah, Zhoushan, Busan, Houston, and Prince Rupert (Canada).
Manipulation Against the Flow
Despite their broadening appeal and the tamper‑resistant design work that has gone into MFM solutions, instances show that these systems can still be manipulated through physical or operational interference.
The most well‑known example concerns the bunker tankers Southernpec 6 and Southernpec 7 in Singapore. Between 2016 and 2019, industrial‑strength magnets were placed on the MFM sensors to distort measurement signals, causing the meters to record more fuel than was actually delivered. The fraud resulted in buyers being cheated of over US$300,000 worth of marine fuel oil.
Another recurring manipulation method involves irregular piping arrangements between the MFM and the ship’s manifold. Investigations in Singapore revealed cases where bunker barges utilized connections allowing fuel to be siphoned back to barge tanks during delivery, inflating MFM readings without the receiving vessel receiving the corresponding quantity. Such arrangements directly contravene certification requirements but can be difficult for ship crews to detect without a detailed physical inspection.
Furthermore, MFMs have defined operational limits calibrated for liquid at a constant flow. When clearing the final amounts of fuel from a tank, flow rates may fall outside these parameters, risking unreliable or distorted readings.
Guidance for Shipowners and Operators
Despite the increased use of MFMs and the introduction of regulatory mandates, the crew of a receiving vessel must remain vigilant regarding the ways these systems can be manipulated and take proactive measures to protect their position. As a matter of routine, crews should:
- Always take ship’s bunker tank soundings and witness barge measurements before and after bunkering, even where MFM figures are contractually binding, and diligently retain those records.
- Inspect visible sections of MFM systems, including physical seals, cabling, and piping layouts.
- Request to see the MFM bunker system certificate and verify the unit’s serial number against the paperwork.
- Engage reputable, experienced independent bunker surveyors.
- Issue letters of protest promptly where discrepancies arise between ship calculations and MFM figures, even if suppliers refuse to countersign.
- Ensure crews are fully familiar with bunkering procedures and aware of common manipulation indicators.
Crews should also be aware of the inherent limitations in accuracy when comparing physical tank measurements with automated MFM readings. Even when both measurement technologies are performing perfectly within their certified tolerances, variance between them can still exist.
About Alvin Forster
Having spent 15 years at sea and attaining a Chief Engineer qualification, Alvin Forster held shore-based roles in project engineering, technical superintendency, and marine surveying before entering loss prevention in 2011. He has attained Chartered Insurer status.
NorthStandard in Brief
NorthStandard is a leading global marine insurer and one of the largest Protection and Indemnity (P&I) clubs within the International Group. The company provides comprehensive marine insurance solutions, supporting shipowners and maritime businesses with expert underwriting, claims management, and loss prevention services.
Insuring approximately 350 million gross tons of shipping worldwide, around 20% of the International Group’s total, NorthStandard is backed by an ‘A’ financial strength rating from Standard & Poor’s. With offices across Asia, Australasia, Europe, and the United States, the company combines global reach with local expertise to help clients manage risk, enhance operational resilience, and support long-term success in the maritime industry.
Source: NorthStandard | Alvin Forster