Was the replacement belt supplied by the original conveyor manufacturer? ■

the more we find out the more we know...sorry but its been that sort of day.

Why was the original belt replaced?

As Designer asks: is the replacement belt identical to the original?

Is there any tortuous curvature along the conveyor route?

Is there an extraneous resistance to motion eg seized idlers or a railway sleeper inside? (I learned the importance of welding a grill over the inspection opening in an NCB headchute. It stopped me getting facially impaled by a scaffolding pipe coming at me at 4.5m/s. Mind you it could have been an improvement )

How much material had the beast digested before it became choked & constipated?

Silly one: But; are your instruments calibrated. (I'm taking a break from Spec writing but sometimes ..it sticks.)

Does the design allow you to play with the take up?

How's that for starters?■

Dear Sirs

5-6 years for replacement os belt of this length and type is fairly normal depending on duty and materials etc.

I have had this problem before when client / end user installs a diferrent (often cheaper) belt when replacing to save cost. Often it is not the same, if it is too stiff then the power consumption will increase by large amout.

Also for diameter 250mm the standard panel spacing should be 1.7m and less on curves.

It is not neccessary for the belt to touch all idlers but it shows rigidity and good form.

If the belt is extremely stiff and totally wrong then maybe it will be impossible to procede. If you can get the belt going then in a few days or 1 week it will become more supple and the power will drop.

Do you know the belt msanufacturer ?

Regards ■

Hi

New belt may be having more regidity than required . I have seen after use of conveyor belt for some days regidity is reduced and power consumption reduces.

In case your client is not able to run the conveyor at all and motor trips you may check following

Run the conveyor by removing rollers from the Alternate panels of return side .

Please check from the belt supplier whether they have manufactured the belt as per required regidity . However generally Original conveyor supplier is not passing regidity requirement of pipe conveyor belt to client

please also check transision distance and belt shape at open area of conveyor as incase of new belting is having more regidity transition distance as considered earlier may not be suitable . In such cases i have seen belts not opening at head end due to non availablity of required distance .

A R SINGH ■

Mr singh is correct these points are also true.

Maybe with extra tension and overload power for short periods it can be started and softened but care should be taken and in a little time it could be OK, unless as stated before the belt is totally wrong. ■

The cause of the problem stated has been marvellously diagnosed by Mr Holt. The tendency of many Indian users to perceive the pipe conveyor belt as just another commodity product has generated such heartburn in other instances known to me.

In at least one of these instances, the user was unable to use the pipe belt as a pipe belt since it refused to move and finally had to use it as a regular belt in some other conveyor.

We would be happy to try and address your problem if given the opportunity to do so. ■

Some manufacturers think they can make (or copy) anything. Most bulk handling equipment requires knowledge of the design and application to a greater or lesser extent, not all of which is available on line, in books or programmed into bits of software. ■

Dear Mr. Lai,

Have you solved your problem? Would you like an evaluation on present vs. old construction to tell how to do it?

Of course, one route is to return the bad belt and purchase from the original mfgr. Likeley old mfgr. will not refund because client not clear on construction required.

If you wish to know best construction and present alternative of motor size or additional power required to satisfy system conditions, we are capable to offer design insite for future design specifications. ■

Dear sir

I have contacted the end user . system was running perfectly since last 5 years .old belt rating was 400/3 .Maximum Amp consumed by old belt was 200 Amp

End user have procured new belt of rating 630/4 EP instead of 500/3 Nylon -Nylon from Pheoniex yule . After instalation of new belt they could not run the pipe conveyor with existing 110 kw motor

After 1 week they have changed the motor and gearbox to 160 kw motor . With new drive they were able to run the conveyor and conveyor was initially consuming 330 A . After running the conveyor for 7 days amp reduced to 300 Amp.

on day 8th while conveyor was running during rain . During this peiod conveyor was drawing 270 Amps

Now they have removed 5 nos of return rollers from every alternate panel , now return side alternate panel is having only 1 bottom roller and conveyor was consuming 260 Amp

I have not taken any feedback for last 3/4 days

A R SINGH ■

Originally Posted by sutikshan lai

Dear sir

one of my client is having 1 km long pipe conveyor for last 5/6 years . Conveyor was running smoothly . Last week they have changed new belt .After changing new belt they were not able to run the conveyor

conveyor is having 110 KW 425 v motor with VVFD drive . Now Amp taken by the motor is more than 330 Amp and they are not able to move the belt

New Belt seems to be very rigid and exerting lot of pressure on rolls . Pipe diameter is 250 mm and idlers are spaced at 1.2 m spacing .

After changing the belt pipe formation seems to be perfect as all rollers are touching belt .

SUTIKSHAN LAI

======================================================

If everything else is fine-meaning;

the circuit breakers are not tripped

The drive coupling is not sheared or if fliud coupling is empty from blowing out of the plug.

The lagging on the drive pulleys is any is in good condition

The hydraulic takeup is not over pressured and tripped out/circuit breaker being tripped.

Perhaps the motor or motor settings for the tripping range of the circuit breakers is too low with the new belt. ■

What is the mystery? Thicker, higher strength per ply and more plies means more forming force and therefore more power. Also, poyester vs. nylon increases stiffness.

Seems like it is now under control with a little fiddle. ■

It still begs the question as to why someone thought they could change the belt specification with impunity ■

I wonder which application this is .... is it the Vikram Ispat belt ? ■

Dear Mr. Lai,

Your problem report is already 2 months old.

Is the problem already cleared?

I would expect more than 7 years for a pipe conveyor belt. (depending on the material and another conditions)

What is the reason for change the old belt?Was it damaged? If yes, how?

Why did the belt specification was changed?

Are the idlers ok?

Are you sure about the given capacity?

Did not the conveyor run empty?

Do have more informations about the case, as drawing and components specifications?

I would like to know, for help you, if possible, and to avoid future similar situations.

But I wish you´ve already solved the problem.

Regards.

Alexandre ■

Mr. Lai,

Would you have some photo of the belt at the stations?

Thanks.

Alexandre ■

Dear Sir,

We are fairly familiar with the installation where the belt is operating. We understand that the earlier belt was with three plies and the present belt which is running is with four plies. The belt carries Rock Phosphate and is located in a Phosphoric Acid Plant.

We also understand that the problem of rigidity which was troubling the belt as so often happens with pipe conveyor belts newly installed , has been overcome and the belt is operating to the total satisfaction of the customer.

regards

thundrstorm3 ■

thundrstorm3,

What is the lesson learned? If the original belt worked in satisfactory manner, why was the belt construction changed? Ignorance?

Seems that increasing the drive power about 45% is pretty drastic. What about the belt, pulleys, and structural safety with such an increase? Take-up must be pretty robust. Can you imagine a large OLC having similar problems and similar corrective action? Lucky is was a little fellar.

Now the client sees a larger power draw for life of conveyor? What does the increased power penalty cost the client?

The fabric weave and denier construction as well as materials play a role in belt's behavior. Just the increased ply separation would tend to indicate a danger of 200% increase in beam stiffness and power ((4ply/3ply)^3 = 2.3)

What will client do in the future? ■

So....the belt suppliers should at least advise at their customers about some important features of their products...

It is sad when you buy something expensive like a conveyor belt without some basic comparative informations about it.

Nobody knows exactly (without other efforts), what they are putting in their compounds...commercial secrets.

Just following the standards is not a guarantee for a properly safe and economical operation.

.or am I thinking wrong?

Alexandre Calijorne ■

Originally Posted by calijorn

So....the belt suppliers should at least advise at their customers about some important features of their products...

It is sad when you buy something expensive like a conveyor belt without some basic comparative informations about it.

Nobody knows exactly (without other efforts), what they are putting in their compounds...commercial secrets.

Just following the standards is not a guarantee for a properly safe and economical operation.

.or am I thinking wrong?

Alexandre Calijorne

Caveat emptor

Let the buyer beware.

I cannot understand why a user doesn't go back to the OEM and purchase the spare parts from them . If they go elsewhere and the equipment fails they have only themselves to blame .

Has anyone lost their job over this fiasco?

If not, they should have, blaming the supplier is a cop out. You need to know what to buy. ■

The excersize goes to show that many in our industry do not have sufficient understanding of pipe conveyor physics. The analytic tools are very complex and, at present, are beyond the capabilities of many.

However complex the problem, there are individuals who will risk the clients' resources on whims of knowledge. We need a few more testimonials to drive the point home. Many believe unacceptable pipe behavior to be a random act.

As long as the random act theory persists, mistakes will be made by the uniformed. So in retrospect, what went wrong or could have gone wrong to result in a very large penalty to the operating behavior:

1. Excess plies = increase forming stiffness resulting in greater pressure of belt on idler roll interface = greater power

3. Construction of each ply adds to stiffer forming - polyester or nylon = more power

4. Poor selection of cover rubber rheology - cheap fillers = higher power

The question remains what is the optimum design. Can the same installation be fitted with a belt design where the power draw, tensile forces and belt seam behavior are better than the original installation. We see that some suppliers-engineers have no clue.

Hopefully, this forum response will lead to a better selection next time. ■

Dear Sirs,

The conveyor belt specifications not always have all information necessary to a correct belt acquisition.

Normally the belt specifications have the main conveyor data, not always with the arrangement drawings of the equipment, the desired tension capacity of the belt , width, tube diameter, and nothing more.

And the final users are not always properly advised about the real importance of the belt construction and its chemical constitution.

Specially for pipe conveyors, this aspects are crucial, but are not always put clearly for the buyers, who are not always properly informed to make some choices.

They just want to replace their belt as soon as possible, under the lower costs.

They want to show they care about the good use of their employer´s money.

Thats all.

And here begins the responsability of the vendors, they must have more care about the final use of their products.

The have to grab the facts deeply, because they know that a pipe conveyor belt application is more complex and this equipment is much more dependent of the belt construction than by the "normal" conveyors.

Thanks Mr. Nordell to show how complex the belt evaluation can be.

I wish a Happy New Year for you al.

Alexandre ■

Originally Posted by calijorn

Specially for pipe conveyors, this aspects are crucial, but are not always put clearly for the buyers, who are not always properly informed to make some choices.

They just want to replace their belt as soon as possible, under the lower costs.

They want to show they care about the good use of their employer´s money.

Competent designers know what is important because their job may be on the line if a machine fails to function correctly. But the extent of this knowledge is commercially confidential intellectual property and not likely to be given away freely.

Buyers just want to buy stuff cheaply and tend to have no grasp of what they are buying. They also seem to be immune from the fallout when it all goes pear shaped and blame the supplier. They bought cheap and should accept the consequences. Expecting OEM's to supply full details of parts so that all spares can be bought from companies who can manufacture but not design (and hence be cheap), is to eventually bring down the OEM as somewhere design has to be paid for. Long term the user will suffer because the knowledge held by the OEM will disappear and at best will have to be re learnt by new manufacturers with mistakes being made along the way, followed by more and more requests for help on forums like this. ■

Originally Posted by sutikshan lai

Dear sir

one of my client is having 1 km long pipe conveyor for last 5/6 years . Conveyor was running smoothly . Last week they have changed new belt .After changing new belt they were not able to run the conveyor

conveyor is having 110 KW 425 v motor with VVFD drive . Now Amp taken by the motor is more than 330 Amp and they are not able to move the belt

New Belt seems to be very rigid and exerting lot of pressure on rolls . Pipe diameter is 250 mm and idlers are spaced at 1.2 m spacing .

After changing the belt pipe formation seems to be perfect as all rollers are touching belt .

SUTIKSHAN LAI

Use same belt manufacturer. ■

Although it is true what you say, I must say that I have not installed a pipe conveyor system which did not pull away.

If the theoretical absorbed power is close to the installed then it may depend on motor overload to pull away initially when empty.

But the requirement depends on idler rolling restance, belt rigity and specification, belt profile and if touching all idlers or not and ambient temperature.

In any case it can take up to 1 month of running to get to the minimum stable power depending on the above factors. ■

Paul & All,

Pipe conveyor power demand varies with:

1. Designer,

2. Supplier,

3. Belt manufacturer and

4. Ultimately the end user/operator.

Obviously, the proof is in the measured operation. We see specifications on belt power based on DIN f = 0.020 to 0.055, ignoring details on where these numbers come from. They spell big differences of opinion, knowledge, and experience. I find the 0.020 number to be obsurd. I frequently ask what are reasonable numbers?

Paul: are you willing to discuss your criteria? I will do the same per quid-pro-quo. The industry can then see some details of working systems. New improved systems are being installed that will give new insight to the design criteria. ■

Dear Larry and All

Yes the variations you mention in 1, 2, 3, 4 are all true to reduce this variation and 'unpredictability' the best design parctice in each case should be utilised of course.

Regarding idlers low rolling resistance idlers should be used and to know what it is not to just put any idler on the job <180grms is good. I would generally use din f=0.03 and 0.035/0.042 in cold weather conditions.

The idler panel spacing is important the greater for reduced idlers but not too large so belt start to open with greater resistance.

Regarding the belt in the early days nylon fabric was common it was very durable but stretch more and after running would reduce in diameter so not touching all idlers, this reduced power considerably.

I have installed pipe conveyors of say diameter 300mm with different strengths and ply No and in one case after 1 week it was not touching all idlers and in the other case touching all idlers for 5 years, in both cases the system worked without problem.

Now new belt developements are High profile and high rigidity these give the customer a better looking profile but generally use higher power.

So it is not so easy to be as precise as with conventional conveyors but it is possible to close with an allowance in the worst case or in some few cases the installer can be caught out. ■