Category Archives: CBM General

RCM as a start point – no not really!

Planned Maintenance

Shakesby LinkedIn Post

This is an excellent article which makes very good reference to the potential benefits of RCM analysis on maritime assets. My only general concern, borne out of extensive discussions with ship management companies, is in regard to the investment/reward argument for deploying a full and formal RCM study in this sector. What I mean by this is that a blanket approach to RCM on a greenfield vessel is not considered to be a commercially attractive way to improve the operational reliability due to the cost to perform.

There are seven basic questions in RCM that must be answered – but who knows the answers? It is noted by Moubray that RCM cannot be performed by an individual nor indeed by members of a department but by a broad group of stakeholders, all of which bringing their own perspective, engineers from the ship, asset specific engineers, facilitation and process experts etc. These should all be in the room or at least be consulted in order to ensure that the RCM process is applied wisely as should the OEM.

We have been involved recently with reviewing RCM studies for UK vessels and have been left short by the fact that many of the system studies under review were completed by lone individuals, albeit with excellent skills and experience. This approach being borne out of commercial cost cutting. Whether the RCM output is good or not the scrutiny that would follow if tested, would likely conclude that RCM process had not been followed and as a result its output flawed.

This is why I do not recommend RCM as the starting point, far from it! When organisations recognise and decide to act upon a change management programme to deliver improved reliability, safety and performance and thus target the reduction of through life costs there becomes a need to shift the general strategy away from planned preventative tasks, as scheduled by a static system, to an optimising role where a greater proportion of time is devoted to finding better ways to do things. Thus, the first task is to establish the current state of the nation and to understand what the business goals are and what risks there are within the current approach to maintenance to being able to achieve these goals and to do so competitively.

The principles and general philosophy of RCM (RCM II Mowbray – for me) are excellent! Unfortunately, when embarking upon a business improvement initiative the change management and RCM facilitation costs far outweigh the clear measurable benefits – this is especially clear when we recognise the degree of redundancy we have built in due to the regulatory framework for ships.

That said, I do believe in RCM and actively promote it as a best practice approach, however,  I tend to embrace an optimising approach where you revisit the existing maintenance schedule and then take steps to understand where it is useful and where it is not. (Compare and contrasting the PMS and maintenance status for an organisation vs. its business needs) . One can then perform a criticality assessment based upon these needs and list all the systems in criticality order. From this you can chose the most appropriate strategy for each group of systems.

For example,  you may chose to group in low, medium and high categories for assets assessed under multiple criticality headings of safety, reliability, compliance and environmental consequence of failure.

You may then decide to run to failure all low criticality assets, perform CM and PM as necessary on medium criticality assets and perform OEM + CM on high critical assets – as a general headline strategy.

One can then extract the work order and frequency from the PMS and review either the total asset base or simply assets at each criticality level. The job, frequency and degree of invasion- grouping jobs as necessary and redefining criticality based upon ability to protect using CM, PM etc. – can then be re-uploaded and incorporated into the PMS.

This can be done in small packets according to resource and desire. In addition should it be deemed relevant a full RCM study could be conducted on high criticality assets to ensure that a function bespoke FMECA has been carried out and all single point and hidden failures considered and managed for these systems.

In short a multiple strategy approach. This appears to be more attractive as it allows companies to take bites according to their needs whilst retaining a robust process.

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Not all scavenge drain oil analyses are the same

I can report that not all scavenge drain oil analyses are the same. There are many approaches and the end user needs to be specify the right approach.

Scavenge Drain or Used Cylinder Oil analysis cannot be viewed as a conventional lube oil sample. There are a great many variables that have to be accounted for and normalised before any diagnosis can be made.

Firstly there is no sump so there is a need to understand the relevance of the results to the engine condition at the time of sampling. Therefore feed rate and engine conditions need to be known RPM, %MCR, coolant and scavenge air temperatures, relative humidity and air intake temperatures. These factors at a minimum will indicate the likely conditions that the CLO will experience in terms of dwell time on the liner wall and exposure to water laden air. Both are factors in determination of the potential for corrosive conditions being present.

To get this information you require accurate power information as the feed rate will be normally calculated using grams per kWh, also power loss due to weather, hull condition rudder angle will impact upon the power to rpm relationship. Knowledge of the fuel quality during sampling allows you to understand what abrasive materials may be present and to what degree the presence of unburned or partially pyrolised fuel has on the lubricating qualilty and the determination of BN and viscosity values.

Clearly this information is not required by all analysis providers – FOBAS Engine provided by Lloyd’s Register, a service which I lead, is one service which considers the holistic view in this way – noting that FOBAS Engine has a wider remit for engine performance optimisation and training and is not simply provided to check feed rates etc, though this is performed and opportunities for CLO cost reduction are usually the first to be targeted.

What is clear however, is that there are significant differences between onboard analysis and lab analysis as well as differences between oil analysis suites.

As corrosive ear generates smaller wear particles which are not within the visibility of onboard magnetic PQ devices, these devices should only be used to warn of unexpected scuffing – therefore permanently installed in the drain line. Using the same technique onboard but offline for periodic sampling is often cited as being used to demonstrate that feed rate has not be “over optimised” to the extent that the oil film is being routinely disrupted and producing adhesive/scuffing wear debris. My view is that in reality this level of feed rate optimisation leaves no room for error and is in all probability a false economic approach in this application.

For lab analysis – there are the issues of immediacy for obvious reason but if your laboratory uses a sensible approach to dilution correction to normalise the effects of contamination by system oil, fuel, water and feed rate variability. Then it is perfectly reasonable to use such a test suite to help optimise feed rate in accordance with variations in Sulphur content and differences in CLO BN performance.

I would recommend to check that your lab based CDO analyses are subject to at least a system oil correction and I would also strongly recommend that a scavenge space cleaning regime is built into the schedule to ensure that each sample represents oil arriving via the liner and not simply that which has accumulated over the previous few days which will have no useful relevance to the operation at the time of sampling and thus weaken any diagnosis.

I would suggest that samples be drawn during steady state operation at a point approaching port which will allow the samples to be passed to the courier in the shortest time possible in order that your laboratory can get the results back to the ship in the shortest time thus increasing operational relevance to the task.

Quote 

“It cannot be stated how much care must be taken when assessing scavenge drain oil …..
Unless some extensive form of dilution correction is undertaken based upon knowledge of the fuel oil, new and used system oil, feed rates and operational data collected from the engine at the time of sampling, use as a routine condition monitoring tool is limited to the measurement of significant changes issues such as high iron, water or BN change.”

CIMAC Used Engine Oil – User Interpretation Guide
Guidance Number 30 issued 2011

Meeting the regs is the bare minimum you need to do to trade

But it’s not the level most shipping companies are operating at!

Most do better… much better

MER March 2013 – Accepting CBM Article

This month I had the pleasure to be interviewed by the editor of Marine Engineering Review, Namrata Nadkarni, to chat about the role of Class in regards to condition monitoring and condition based maintenance.

  

In reading through the resulting copy which is attached above and I realised that the point that came across most clearly was that most shipping companies do far more than they are required by law to do and they do it for some other motivating reason.

I would say that, in the main, those who fall foul of the survey process do so not because they are actively cutting corners but because they have “dropped the ball” briefly and have been focused elsewhere.

This lead me to surmise two additional points; 1 – that even then most minimum investment in routine CM can be useful by means of demonstrating ongoing reliability and 2 – That where companies seek to do better than the minimum they do so at their cost and do so because of some other value judgement. What I mean is that we value other things and measure success in other ways than simply price. We know this anyway otherwise we would all be driving the cheapest cars or wearing the cheapest clothes, the same is true for businesses. Yes we must make money and doing so routinely is the goal of all companies but we also have to create value in often intangible ways. Reputation, quality, reliability, safety, alignment with certain values, environmental position etc.

We held a CM Forum at Lloyd’s Register recently where the subject of justification for CM was discussed. Our conclusion was that simple “Cash spent – Benefit returned” models are meaningless as they make an assumption that failure prevention and reliability enhancement are purely proportional to the amount of cash invested in the maintenance process – related yes, reliant – to some extend, but dependent – I think not!

We concluded that risk avoidance and risk reduction was a more useful form of currency to use to define the benefit of moving towards a more intelligence lead strategic maintenance management process.

So in short look to the wider non fiscal benefits, to the community, to the process of operation and the process of maintenance and to delivery of marine transportation services that we can be proud of.

The smart money is where its at!

Marine Machinery Condition Monitoring – Marine lags other industries why?

I have condensed some thoughts into a short paper which I am presenting at two events this month;

MPMM Sunderland 12th and 13th September 2012

and IMarEST CBM Conference 26th and 27th Septemeber 2012

IMarEST CBM 2012

This does not presented to be the definitive word on the subject but is instead intended to promote discussion and debate that moves the process forward. Also CBM is only one solution that may only be relevant to some of the fleet. Mostly there will be combinations of strategies that are best in each case. However, what is certain is that we have to promote best practice, where in the main compliance is the minimum entry standard.

As we globalize and the boundaries between elements in the supply chain become blurred the weak ones with stand out and this will lead to commercial opportunities for the better maintainers.

Have a read of this and feel free to comment, criticise, argue etc! Your opinions are important as your silence now may impact upon the course that industry takes.

Read PAPER here — Ship Machinery Condition Monitoring – Sunderland 2012

My LR Blog — http://blog.lr.org/author/dannyshorten