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When an option is available to repair or replace an item, traditionally it was merely an economic decision. There are some consequences to the 'replace' decision e.g.,
1.'Replace' is a PM action; the item still has some useful life left at the time of PM
2. Useful metal or other materials may be recovered from the scrapped part, but there are energy and other processing costs
3. 'Repair' generally needs more skill than 'replace'. In time the skills may be lost due to lack of use when 'replace' becomes the preferred option
The 'economic' model does not take these into account. Only the measurable and opportunity costs are considered
On the flip side though, 'replace' decisions keep the economy active, jobs secure and everybody happy. Will it keep the economy competitive?

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Nice one V. I have noticed a decline in force capability.
It is more apparent as baby boomers retire here in USA.
Sorta snuck in here last 10+ years simple cylinder and valve repacks seemed to stop happening.
Then pumps, gearboxes, valves, regulators etc.
Vendors think im nuts when I ask 4 rebuild kits and repair componants etc now.
It has developed into bigger buisness to factory rebuild everything.
I think factories will not even have what I view as a skilled multi craft tech in 10 more years.
Just a bunch of parts changers who barely know how to troubleshoot.
I recently had to explain to penny pinchers why I needed a 40 ton. hydraulic shop press here at a metal roll forming mill.
So you see the mentallity of getting things done is even wrong now.

Here is to you baby boomers getting more done with less !
I thought what can be repaired, should be repaired. It heard one guy said, regarding replacing or retubing a shell and tube heat exchanger, it should last forever if repaired properly. In fact, this guy went on to say that all static equipment should last forever provided repaired properly (I guess to AGAN).

I guess the above view assumes that there is no temperature fluactions which may cause fatigue cycles. In this heat exchanger which is in fact a reboiler, there is somewhat temperatures fluactions occurring especially during trips or shutdowns.

Another case is regarding a PSA (Preesure Swing Adsorption) adsorbers (4 pressure vessels really), the design specifies a life cycle. So it was decided very quickly to replace these vessels upon reaching the specified lifecycle. Even when the OEM said the pressure inviolved is considered low, it will just shoo... according to him when it leaks through the walls whose weld joints were MPI every recent shutdowns.
I thought repair is the first option and replace is done if cannot be repaired.

However, small equipment like those stated may be replaced on site straight away to reduce downtime and repair the kaput item on worshop's own time. So the repaired item be put back to inventory as reconditioned item.

Replacing field insutruments is probably common compared to repairing them.

What massive environmental impact does this repair or replace decision has? I guess all are dumped as scrapiron.

Is this a consultancy work or academic/student question?

Recycling scrap materials could be a lucrative business. There is a Chinese billionaire making his fortune from recycling construction materials and actively doing philantropic works now. I forgot his name.
It comes down to its core state "Whats it worth?"
And is there time and k/s.
Some times rebuilding a electric motor that costs 140 usd is rite and others wrong.
No single answer is correct all the time.
I look to rebuild / repair nearly everything even electronics items.
Before or after machine /system is returned to production depends upon situation.
This means, I might buy a new replacment item, then place the reworked one on shelf.
I have spares of different RFI status; red card = temporary use thoubleshooting item.
yellow= temporary use not good as new condition. green= Rfi spare part.
I leave card on item if possible unless green, and record info.
Then with machinery up and producing, I start with removed item If I cant repair and get a RFI new quality part I buy replacment.
We do this all day every day. what messes up the soup is when bean counters try to mandate this with a formula based upon mfgr. perfect testing conditions.
How many recalls did Toyota have last year?
Ill bet all those parts were tested good for 100000miles/ ten years service life by factory.
This is where reallity and murpheys law hit bean counters formulas at Toyota last year.
I would like to believe thier tests were as scientific and comprehensive as they could be.
Yet look at all the recalls!
Last edited by Registered Member
Please recall that I posted my question on the 'Green Reliability' thread, for a specific reason.
A lot of us talk about 'green', so my question is what do you actually do?.
The responses so far indicate that economics and circumstances determine our decisions, as they have always done in the past. I have not seen evidence to support the view that not many of us take the trouble to look for green solutions, unlike for example, Terry'O was doing when he was designing 'green' toilets.
My question was merely aimed at understanding whether 'green' influences our decisions. There is no right or wrong position, at least from my perspective.
Most things esp'ly metals will go to scraps so recyling is green.

Soemtimes, when it goes to replace motors, one of specs should be higher efficient motors of course with same or cheaper maint cost. The same seems to go for other equipment replacement or repair cum upgrade or plant changes.

Also I heard plant optimization is done for a higher energy efficiency (ie greener) and higher production.

But, I heard one project steam decoupling is done for easier operations even though energy efficiency is lower.

I thought most OEM will go for better and greener products when economically viable.

Electricity production seems to continue from fossil fuels until renewable energy is cheaper and environmentally friendly. So energy machines will continue to be repaired or upgraded rather than replace with different machines.

Hydroelectrics seem to be leading eg Bakun in Sarawak Malaysia. The cheaper energy is planned for aluminium smelting plant and other energy intensive industries (to attract foreign investments)under SCORE project.
I have not explained myself clearly, I guess.
First, I am only talking about where there is an option to repair or replace, e.g.,

a) Do you rewind a small (fractional HP to say 10 HP) motor?
- Replace if it's too difficult to rewind and/or cheap. Repair if replacement not available and if can be rewound.

b) Do you replace a starter motor assembly of your diesel fire pump or repair it?
- Same as above.

c) Do you replace a mechanical seal assembly or repair it? etc.

Normally repair if spare parts available from OEM. Otherwise replace with a new set esp'ly if difficult to reassemble.

To repair or replace, that is the question... Many factors do play into that discusson and it is really on a case by case basis. How about replace then repair. Now I'm confusing people. About being "Green", well what are we talking about here, small throw away gearboxes or multi-million dollar tooling. Well I think I just answered my own question. If the cost to repair is more than the replacement cost, then you are just wasting (the company's) time and money. Maybe you can't replace it or OEM parts are not avialable, then the decision has been made for you by someone else. I think if you want to make "your job secure" make the right decision...

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