This Month's Topics

1. Tips from the work place. (Three tips PLUS info. from a reader on why stainless steel cracks on welding.)
2. April and May UP-TIME topics. (For your information.)
3. New Asset Management Topics for UP-TIME. (More on the world of asset use and care.)
4. How to make your Planner successful. (Let the Planner do his job)
5. Makes you think. (A bit of introspection.)

1. Tips from the work place. (Three tips PLUS advice from a reader on why stainless steel cracks on welding.)

Don't re-weld stainless steel welds

Dear Sir,

With reference to your above tip (In the April 2002 Newsletter) I wish to convey to you the information below. I hope you will pass this to all your readers.

SIGMA PHASE: In addition to ferrite, austenite and carbides, another micro-constituent is found in many stainless steels called 'sigma phase'. This phase is hard (800vpn), brittle and non-magnetic and is formed from ferrite with considerable diminution (reduction) in volume. The volume reduction causes fine cracks as the sigma phases form when steel is heated in the range 500-1000 degree centigrade very slowly in pure iron-chromium alloys,
somewhat quicker in Fe-Cr-Ni alloys and much faster in Fe-Cr-Si alloys. In 18/8 alloys the addition of ferrite forming elements - silicon, niobium, molybdenum, tungsten - make the steel susceptible to sigma formation unless the austenite is stabilized by raising the nickel content. It would appear that as sigma forms, local alloy depletion occur as a result of the sigma phase becoming enriched in ferrite forming alloys, particularly chromium.

The above reference is taken from the book 'Metallurgy for Engineers' by E. C. Rollason (ISBN 0 7131 3282 5).

With regards,

Ebenezer

Bag House Dust Collector Cleaning Discovery

In the March newsletter there was a tip to cutback the pulse cycle times on pulse-jet bag house dust collectors to prevent over-cleaning from destroying the dust bags. We have been experimenting with the cycle time on a 49-bag unit used in a copper sulphate drying circuit. We found that it took three hours with the pulse system turned off before the differential pressure across the bags got to 1 kPa (100 mm or 4" of water) from the initial value of 0.5 kPa. And once the pulses were put back on it took two cycles to clean the
dust off the bags and bring the back-pressure down to 0.5 kPa. In our case this represents a huge reduction in dust bag destruction and plant air use.

The time it takes for the back-pressure to go from low to high limits (1 kPa to 1.5 kPa) depends on the dust content of each individual process and the results noted above will not reflect your situation. However what the discovery tells us is that there maybe a big opportunity to extend bag life
and reduce compressed air consumption if the time between cleaning pulses is extended to the allowable back-pressure limits. We are now installing an automatic pulse cleaning control system based on differential pressure across the bags.

Watch out which way your bearing housings are loaded

The ability of a bearing housing to take a load is not equal in all directions. Bearing housings are designed to take loads acting toward their base. If the load acts to pull the bearing cap away from the base it is only the cap
holding-down bolts that take the load and not the bearing housing base.

We have had a situation where a duplex drive chain acted to rip the bearing cap away from the housing base. I suspect that with continual, fluctuating loads over time, as well as stop-start inertia forces, the cap bolts loosened-off or stretched. Finally an unexpected overload snapped one of the cap bolts.

It appears the broken piece of bolt fell between the sprocket and chain forcing the duplex chain to ride-up over it. The 80 mm (3") pulley shaft on which the sprocket sat bent and the duplex chain snapped. We were down for two day and had to make a completely new shaft. It took 4 people out
of the system for two days to do the repairs.

It may never have happened if the bearing housing had been properly oriented in the first place, so the loading and forces went through the base of the bearing housing and not out through the bearing cap. If you have such a situation at your place make sure the cap bolts are tight. If you are
still concerned, consider installing a torque limiter or electric current overload protection on the drive. If it is a greased bearing, one other option is to turn the bearing housing around and mount it so that the loads go through the housing base.

A simple way of gauging viscosity

Here is a 'rough' way to gauge viscosity of thick liquids. It comes from a supplier of tank agitators.

"Regarding viscosity, 5000 cps would be a bit more than a heavy paint (more like a hair shampoo). On the other hand 10,000 cps would be towards a hair conditioner or tomato sauce (ketchup) which you have to squeeze out of a container."

2. April and May UP-TIME topics. (For your information.)

Volume 3 Edition 8 topics (April 2002)

a. Moving slurries about.

b. Belt conveyor tuning.

c. Effects of process flow & pressure changes on electric motors. (One that every operator ought read!)

d. Pump life extension - the impeller.

Volume 3 Edition 9 topics (May 2002)

a. Heat transfer basics. (Need this to develop thermodynamics further.)

b. Fired package boiler basics.

c. Conductivity probe operation & use.

d. Lubrication and cleanliness. (Some interesting facts about water contamination.)

e. Defining work order priorities.

3. Asset Management training now to be part of UP-TIME.

From May 2002 onward UP-TIME will start educating production and maintenance personnel in asset management.
Topics will include CMMS, condition monitoring and non-destructive testing, predictive maintenance, planning and scheduling, preventative maintenance, RCM, RCA, TPM, risk based maintenance, overall equipment effectiveness,
strategic initiatives and much more.

You probably know this saying "Give them a fish and you feed them for a day. Teach them to fish and you feed them for a life time."

UP-TIME is all about life-time engineering and asset management learning for operators and maintainers. The more they know and apply the more competent and able they become. Knowledge is an investment in a better future for you and everyone else! Happy fishing!

.4. How to make your Planner successful. (Let the Planner do his job.)

This is a shortened version of a recent presentation made to the Western Australian chapter of the Maintenance Engineering Society of Australia in Perth WA.

MAINTENANCE PLANNING

Make your Planner successful!

BACKGROUND.

Why plan? Planning maintenance work maximizes the benefits from the time, money and effort that go into a job. There is plenty of evidence around that proves the great value gained from maintenance planning. The "MAINTENANCE PLANNING AND SCHEDULING HANDBOOK" by Doc Palmer, published by McGraw Hill, presents clear evidence of the benefits that accrue by planning the work for your maintenance crew.

The difficulty people have with the planning process is to decide where planning starts and stops.

THE KEY CONCEPT BEHIND PLANNING.

The Chinese philosopher Confusus said - "In all things success depends on previous preparation and without such preparation there is sure to be failure."

Confusus was right. If you want things to be done successfully they must be prepared, and made ready, before doing them. The job of a maintenance planner is to prepare for the work of doing maintenance. The job of a maintenance scheduler is to prepare for the people to do the maintenance. The planner first organises everything in readiness for a job to be scheduled. But he cannot schedule the job! The persons responsible for providing the people, and the access to the equipment, must do the scheduling.

When the planner hands over a complete work pack his job is done. He is successful at the point of hand-over. He has compiled and assembled the parts, tools, resources and information needed to successfully do the work. He has done his job! He then goes back and starts preparing for the next
lot of maintenance work.

A planner's job perspective and requirements are to:

1. Plan first.
2. Plan in detail.
3. Plan then purchase.
4. Hand over the completed work pack to Maintenance.
5. Go back and plan the next job.
6. Maintenance supervision schedules the planned work with Production supervision last.
   

The Planner's time scale is 5 days away and longer. Planners cannot help with breakdowns and rush jobs. It is already too late to plan! In a breakdown you can only react to what you find during the repair. The maintenance crew
leading hand looks after breakdowns, and those 'must-be-done-today' jobs.

Don't bother your planner if it's a breakdown or if the job must be done within the next 5 days. The planner's job is to get ahead of today's problems and prepare for next week's successes. If you stop him from doing that you will
stop having future successes. The planner's success today is everyone's success tomorrow!

THREE QUESTIONS.

What exactly is maintenance planning?

To satisfy Confusus' advice, maintenance planning is about preparing to achieve success. Do what ever is necessary to guarantee successful outcomes.

What exactly should a maintenance planner do?

To maximize the benefit from time, money and effort the planner must do all the thinking, reading, procedures, investigation and procuring so that the maintainers spend more tool-time on the plant and equipment. Good planning means high tool-time, it means machines are fixed quickly, they are fixed well and with less people and supervision.

Where exactly is the maintenance planner located so that his job can be done properly?

The planner's time focus is 5 days and longer. He cannot sit where the maintenance time focus is today and tomorrow. He must sit in an area where he is not disturbed by day-to-day issues. He also needs to be in contact with Production so he can get a feel for their priorities and
production schedule. The planner sits in the Production office.

The planner must report to people whose time focus is longer than 5 days. He cannot report to workshop supervision whose time focus is today and tomorrow as the planner will then become the 'goffer' for rushed work and never find the time to be ahead of the work load. The planner reports to
the Maintenance Manager and not to 'shop floor' supervision.

CONCLUSION.

Let me say it one more time, because it is so important to your success -

"The Planner's job is to get ahead of today's problems and prepare for next week's successes. If you stop him from doing that you will stop having future successes. The planner's success today is everyone's success tomorrow!"

Mike Sondalini

Equipment Longevity Engineer

5. Makes you think. (A bit of introspection.)

This is from Noel Whittaker's 22 April 2002 financial advice newsletter.

Buddhist poem - Autobiography in Five Chapters

1) I walk down the street.
There is a deep hole in the sidewalk
I fall in.
I am lost.... I am hopeless.
It isn't my fault.
It takes forever to find a way out.

2) I walk down the same street.
There is a deep hole in the sidewalk.
I pretend I don't see it.
I fall in again.
I can't believe I'm in the same place.
But it isn't my fault.
It still takes a long time to get out.

3) I walk down the same street.
There is a deep hole in the sidewalk
I see it is there.
I still fall in....it's a habit
My eyes are open
I know where I am
It is MY fault.
I get out immediately.

4) I walk down the same street.
There is a deep hole in the sidewalk
I walk around it.

5) I walk down another street

That's it for this month's newsletter,

Best regards to all,

Mike Sondalini
Managing Editor
Feed Forward UP-TIME Publications

Mike Sondalini is the Maintenance Manager and a practising maintenance engineer with one of Australia's most progressive mid-sized chemical manufacturers. He is in charge of a maintenance crew comprising mechanical fitters, boilermakers, civil trades and electricians who together maintain a wide variety of equipment in very trying production environments. He writes to provide practical engineering knowledge for engineers, trades people and plant operators.

He is also the founder of www.feedforward.com.au  which is a specialist web site devoted to teaching engineering to plant operators and maintainers to help them "solve problems, make better decisions, dispel old myths and become multi-skilled."