Hello,

Design Out Maintenance is an option resulting from RCM.This should eliminate the need for maintenance.

Could someone please give me a few examples of such an approach, to understand it better? Thank you.

cheers

Hi Rennie,
Here are a few I can think of.
1. If you have a hidden failure you can modify something to make that failure evident so no failure finding maintenance is required (you will still need to fix it when "it is broke") One example is a standby generator that was modified to run continuously. The company made front page news when power was lost and the standby generator failed to start or started but stopped soon after. The modification cost money but saved the red faces.
2. In structures, beef up the structure to the point that it will outlast the life of the asset so no inspections for corrosion or fatigue etc will be necessary. This analogy can be used for all items that have a safe life. Make the safe life past the life of the asset (at least past your predicted stay with the company ).
3. If you have random and unpredictable failures for which there is no feasible preventive or predictive maintenance you can design modifications to stop the failure from occurring. To avoid the cost of punctures to tyres, change to rubber tyres (note that punctures will stop but other failure modes like wear will require maintenance).
Hope these help
Steve

It has been said that design out option should be the last resort to do, after taking all efforts to make the PM & people to work. How true is this?

Josh,
You will probably get a variety of responses to this question.
Our view is that the PM can be changed quickly without a lot of cost (on most occasions) whereas design out (modification) can take a long time and cost a lot of money. Mods also tend to go on the long list of other mods so unless the ones that come out of your workshops have record breaking ROI, they don't get done anyway. Companies dont go with every mod that has a positive NPV - only ones that have startling returns.
You have my thoughts at least.
Regards
Steve

Steve, do you mean by startling returns, the highest returns or does the word startling refer to quick returns or low-lying fruits which are mind-catching?

I learnt a bit about project ranking or prioritization when in the school but wondering whether industrial plants really apply this technique when deciding what modifications to do?

Rather, I guess they just decide whether the modification projects are required or not after simple cost/benefit analyses for individual projects, without going through extensive project ranking studies for all modifications proposed.

If project ranking is done, who will lead & coordinate, maintenance or project dept who will owns the modification change request or finance?

Hi Josh,
To me, startling returns means that the payback is weeks. This is quick return. These mods may be (and often are) low hanging fruit so they are one and the same in my mind.
The methods of managing modifications in industry vary so much that it would be difficult to make any assessment on how much ranking is done.
In some companies, the technicians modify things as they please without any consultation.
In others, there is tight control and all modifications go through the headquarters, no matter how small or insignificant.
Most have no rules about this so the processes are haphazard and left up to someone to say yes or no. In companies that do have a process, we often find that if the problems are significant and the process of modification approval is onerous, the supervisors will turn a blind eye and the mod will happen regardless of the rules.
So there we have an assessment of what I see.
Not good news for a profession that is supposed to be a profession.
I think in some ways we have a long long way to go.
Steve

I do see plants use plant modification request procedure & form. Without this would be a sure deficiency in procedures, needless to question its effectiveness. However, I haven't seen extensive project ranking done for all modifications proposed, let say before the new budget cycle. Is it done elsewhere?

Thanks Steve for the examples.

I'm sure people out there have met Design Out Maintenance situations and would be very greatful if they can share them with us.

Rennie, Josh,

Using RCM, design-out is applicable under certain specific conditions, namely
1. There is a failure mode for which we cannot find a maintenance task to mitigate against the consequence of failure. Usually (but not always) such failure modes are hidden and affect Safety/Environment.
2. When there is a wear-in failure mode (infant mortality)redesign may be economical.
Note that redesign is not merely that of hardware or sofyware; it can be of people(training) or procedures (revision).

Rennie, designing out a failure mode invariably introduces a new failure mode. For example, you can add a dashboard indicator light to tell you if your car brake light has failed (hidden failure). If the indicator light comes on, you can replace the brake light bulb (as Steve explained), BUT you have a new (hidden) failure mode of the indicator bulb itself.

Remember that as long as degradation takes place, you cannot eliminate maintenance.

Every time we modify equipment, i.e. implement design-out, we add a new layer of risks. Sometimes the solution is worse than the problem! In high hazard industries ALL modification go through a strict change control procedure. A full blown HAZOP is often required. Hence,one has to think carefully before undertaking redesign. This is the reason for the high hurdle, of the kind Steve explained ( requiring startling results).

Josh, top performers use a risk ranking of all modifications with e.g. a risk matrix. They also impose hurdles to prevent people proposing design-out solutions willy-nilly.

To sum up, design-out is a valid and applicable strategy, to be used when certain conditions are met. They are not magic wands to be waved about.

Clarification: What do you mean by risk ranking for modification projects using risk matrix? Is this similar to equipment criticality assessment based on failure consequence?

I agree we shouldn't do modifications free-willy like on our cars. That's why I believe some initial screening is required to decide whether full blown HAZOP or QRA etc is needed or not for each proposed modification.

I expect the screening to identify and speed up simple or minor modifcations which are considered not risky eg installing minimess fittings, bleed eyes, gel dryer etc for lubrication-related purposes.

P/s I watch many car mods or bike fabs in tv by Orange County etc. I wonder whether they need government authorities to drive these non-standard designs on the roads because no parts of applying for authority approval are shown in the program. Is it regulated or not?

This message has been edited. Last edited by: Josh,

Josh,

Yes the risk matrix is similar to the one for criticality, with a probability and a consequence axis.

Alain Prost died in an F1 car crash. One of the findings of the crash enquiry was that the steering shaft had been shortened at Alain's insistance. we never learnt whether a HAZOP was done or not. So much for your Orange County TV show.

Even 'simple' mods like on lubrication or cooling systems can have formidable consequences, under certain conditions. ALL modifications should go through a risk assessment. If the various operating scenarios can be easily defined, the assessment is relatively easy. Based on this assessment, you can decide whether further risk evaluation e.g., QRA is required. When scenarios are hard to define, one must go through a HAZOP or equivalent.

quote:

Originally posted by Vee:
Alain Prost died in an F1 car crash. One of the findings of the crash enquiry was that the steering shaft had been shortened at Alain's insistance. we never learnt whether a HAZOP was done or not. So much for your Orange County TV show.

While I am in agreement with your comments, Vee, I'd just like to note that the racer you are probably thinking of is Ayrton Senna, who was Alain Prost's rival. Or something like that; I have little knowledge of the sport myself, but a close friend of mine is an enthusiast and he loves to overwhelm me with all of these facts that I sadly have little interest in!

I'm just surprised to have finally found some use for what he's been babbling about for so long.

Laura

Laura,

Oops, I was thinking of Ayrton Senna, sorry Alain! thanks for correcting me before too much damage was done!