Kindly define 'reputed' and also examine your 'experts' design. It appears that this design process did not properly address belt life since it is not mentioned with their other talents. Belt must surely be the largest expenditure and it seems quite an oversight to leave it to the end. If the supplier is as reputable as you say then he has good reason to put his neck on the block and you must ask him first. There is no mention of predicted belt life for other potential suppliers and my own conclusion about this is that you have chosen the cheapest and only now looked at the lifecycle costing. It happens all the time.

Pipe conveyors have the dilemma that they themselves cover the material and hence make other covering wasteful.

For an installation lasting 20 years the belt life should be 10 years. Ozone and radiation play their part and many manufacturers predict a life expectancy of about 12 years. Anything longer is waste of CAPEX. ■

Originally Posted by Roland Heilmann

Sir,

above figures cover also my approach.

However:

Do you have perhaps a heat or abrasion issue, which did arise only at a later stage?

Regards

R.

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Usually, the main wear mechanism with pipe conveyors is the outer cover which contacts the idlers. It is common for conveyor suppliers to fail with appropriate idler alignment. Inappropriate idler alignment will scuff the belt cover off much faster than normal abrasive wear. A one year life warranty, although extremely short, is not unthinkable, unless the designer makes the extra effort a better idler alignment.

By example, pipe conveyors with horizontal and vertical curves must be designed with the idlers and their frame alignments pointing to the radius loci. Usually, the only the end assemblies, either along stringers or in truss assemblies are aligned to the radius loci. All in-between idlers will then scuff the belt outer cover, at various degrees, as can be read by the idler roll surface brightening = more power used and less belt life.

A pipe conveyor can achieve 5-10 years of belt life with proper design, including proper chute flow onto the belt, proper idler diameter and spacing, proper idler alignment, and proper belt specifications.

Another conveyor advancement is use of plastic coating on idler surfaces. This lowers power, noise emission, and increase belt and idler life. ■

Birla copper pipe conveyor was installed in The year 1999 . This conveyor is 3.2 km long and has steel chord belt . The Client has changed the complete belt only once in the year 2009 . Normally steel chord belt life for long pipe conveyors is 7-10 years . Pipe conveyor needs proper alignment and proper belt selection ■

WE see these short life warranties for pipe conveyors. Why? Ignorance. Conveyor designer orders belt, writes installation procedure, but, does not understand the necessary installation tolerances that combat wear of belt outer cover.

I witnessed a 7 km pipe conveyor installation that abraded the outer belt cover down to fabric in less than 5 years. I checked the idler installation - very poor and principle cause of belt life loss. Filed a report with client, showed maintenance personnel the problems. Client orders another longer belt from same supplier bound to install with same errors. $$$$ trumps common sense again. ■

Originally Posted by nordell

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Usually, the main wear mechanism with pipe conveyors is the outer cover which contacts the idlers. It is common for conveyor suppliers to fail with appropriate idler alignment. Inappropriate idler alignment will scuff the belt cover off much faster than normal abrasive wear. A one year life warranty, although extremely short, is not unthinkable, unless the designer makes the extra effort a better idler alignment.

By example, pipe conveyors with horizontal and vertical curves must be designed with the idlers and their frame alignments pointing to the radius loci. Usually, the only the end assemblies, either along stringers or in truss assemblies are aligned to the radius loci. All in-between idlers will then scuff the belt outer cover, at various degrees, as can be read by the idler roll surface brightening = more power used and less belt life.

A pipe conveyor can achieve 5-10 years of belt life with proper design, including proper chute flow onto the belt, proper idler diameter and spacing, proper idler alignment, and proper belt specifications.

Another conveyor advancement is use of plastic coating on idler surfaces. This lowers power, noise emission, and increase belt and idler life.

Dear Sir,

i am a novice in this field. my question is how to check the alignment of all the idler panels to radius loci especially in a compound curve.

would like to hear from you,

Regards,

asok

India ■

Originally Posted by asok ghosh

Dear Sir,

i am a novice in this field. my question is how to check the alignment of all the idler panels to radius loci especially in a compound curve.

would like to hear from you,

Regards,

asok

India

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

There are two ways to improve typical idler installation positions that meet modern operating criterion.

1. During installation apply special positioning jigs that set the individual positions of idler support bulkheads along the conveyor route so they are faced to the radii loci in all planes. Unfortunately, most pipe conveyor designers do not provide this style of adjustment. They orient all idlers within the truss supports to have identical orientation - wrong plan for long life. Once the bulkheads are positioned, idler rollers are loosely fastened to each bulkhead and then finally aligned with a second jig that has the settings to orient each roller in the set to its optimized location. Idler brackets have adjustment to allow this positioning.

2. Survey the position against a theoretical computer generated location and orientation. Adjust accordingly, if your bulkhead and bracket arrangement allows this condition. IF not, then you have selected the wrong designer. There may be options on how to make the corrections, but depend on the design and cost. ■

From experience, though not on a pipe conveyor, a high heat, fire resistant and oil resistant cover tends to be very soft. It consumes excessive energy and abrades away prematurely. The belting manufacturers don't apologize for this. Typically they question if you really need all three resistance features and try to talk you into a compound that can offer better abrasion resistance.

Joe Dos Santos ■

Originally Posted by Author

Sir, we are in a dilemma, a reputed belt manufacturer offering belting for pipe conveyor has given belting life for a conveyor as 2-years. Shocking !!

Belt conveyor length is about 700 m and it receive material from another pipe conveyor about 2.5 km long, for which life has been informed little more than two years.

Material to be transported is bit abrasive like coke, speed is close to 4 m/sec and conveyor has been designed by experts considering all design aspects like number of curves, minimum radii, both vertical and horizontal, starting stopping considerations, using VFD drives, good rollers and supporting frames etc.,

We can understand, the life of belting should be given in term of tonnage transported but the supplier insists life in years along with tonnage, but insists belt may last for for the lower of the two .

Is it possible to know on average for an installation to work for more than 20 years expected life. What should be life of such belting?

If direct answer is not possible, should we get an idea for pipe conveyor installations in the past, what life in general has been achieved.

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

If a supplier could offer a warranty for 4 or 6 years vs. 2 years, what incentive would you apply, where the supplier re-aligns the idlers, or in addition replaces them and controls belt purchase?

Based on my experience in India, its all $$$$, with no incentive for performance. There are no credits for technology. So, how will India advance? ■

Hello,

Once I was specifically deputed to visit MPEB by my first employer (in bulk material handling) to know about MPEB observed real life of important items / equipment. MPEB has been owner and user of more than 25 coal handling plants in power stations. The equipment and system design had been at par with European practice and belts were of high quality India - UK make. This was formally arranged meeting, as a free exchange of views for genuine feedback, for benefit of material handling industry.

As I remember, they said belt life of about 7 to 8 years (for easy material like coal, design, maintenance / upkeep quality as per rules, temperature conditions, etc. as applicable there and plant operation round the clock i.e. 2 shifts in a day for coal handling plant). It is clarified that plant has 2-stream conveying system wherein one is working and one is standby. That means operational hours will be equally divided among two. In those days cotton fabric belts were more prevalent and cotton nylon belts were used selectively.

As against above information, it is obvious that belt manufacturer will have more exhaustive data and their information will be more reliable.

Regarding pipe conveyor, the belt life will be comparatively less because belt is repeatedly bend and un-bend into shape pipe to flat to pipe, which weakens its internal structure. Also, overlapping edges continue to rub each other during course of travel, which reduces its cover life. Well your buyer can also obtain this type of feedback independently. Belt life is not a matter of negotiation in a manner that human life is not negotiable.

The rubber degrades / oxidizes with respect to time. So, can it have life in decades ? The brand new belt / tyre if kept exposed to environment condition (weather, air, rain, temperature and particularly sunlight without use) for 10 years, and then will it be safe to use for car ? Well, what is said by reputed designer / maker of belt / tyre prevails, because it is their product and they know better than others. Your question and resulting information in this forum will certainly enhance the public information about belt life.

A belt life cannot be correlated with tonnes being conveyed. It will give erroneous picture. The belt of 800 mm width will convey certain quantity in 1 year whereas a belt of same construction but 1600 mm width will convey nearly 5 times the material (larger cross section and higher permissible speed as the belt width increases).

The belt conveyor is more robust, reliable and economical because 1) Belt is always in ‘relax’ mode 2) It is easy to install, operate, inspect and maintain 3) For the same capacity the belt width is less by some 35% which contribute to economy 4) It is simple in design and construction which also contribute in economy 5) It consumes less power as it has 3 rollers against 6 rollers, overall conveying friction coefficient 0.02 against 0.035. This information is mentioned here because some believe that pipe conveyor has some superior characteristics and many things can be expected there.

There is general misconception among people that pipe conveyor is superior version of belt conveyor like zoological evolution. Well actual designers concerned with these equipment already know that it is not so. In spite of earlier mentioned drawbacks of pipe conveyor; it has its own unchallengeable place as a distinct equipment, only option when A) One wants to convey material in enclosed form B) The conveying route has sharp curves horizontally and vertically. So, both equipment will continue to exist concurrently.

Ishwar G. Mulani

Author of Book: ‘Engineering Science And Application Design For Belt Conveyors’. Conveyor design basis ISO (thereby book is helpful to design conveyors as per national standards of most of the countries across world). New print Nov., 2012.

Author of Book: ‘Belt Feeder Design And Hopper Bin Silo’

Advisor / Consultant for Bulk Material Handling System & Issues.

Pune, India. Tel.: 0091 (0)20 25871916

Email: www.conveyor.ishwarmulani.comwww.conveyor.ishwarmulani.com ■

Originally Posted by I G Mulaniwww.conveyor.ishwarmulani.comwww.conveyor.ishwarmulani.com

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I rarely disagree with your postings. In the above case I must comment:

1. Belt life can exceed 20 years even with harsh environment ( lump size, sharp edges, loading on steep inclines, high tonnages, .....) example: Palabora transported up to 6000 t/h, 4 m/s, 16 degree incline, 300 mm sharp primary crushed copper ore, was projected to last >20 years with proper curved chute design. Retired after 8 years with nearly full cover intact.

2. Your 800 mm wide belt only capable of 1/5th capacity of 1600 mm wide belt is not correct. Analogy is closer to ~ 1/4 or square of width difference. However, there is a caveat. If large lump is considered (>=150 mm), then your number may be closer. I am picking and straws.

3. Belt life is most dependent on chute design including pipe conveyors. However, with pipe conveyors, belt mfgrs. differ with belt construction. Some subscribe to stiff construction and some to flexible construction. We prefer the later to reduce preforming pressure and skidding or sliding action on idler-belt contact, and the consequential added power higher pressure requires.

4. Belt mfgrs. do not do chute design and therefore are handicapped at predicting true belt life, except by past statistics of older chute designs. ■

Hello,

I appreciate Mr. Nordell for his posting and information about the belt life.

As a general statement, it would be beneficial to many, if this topic generates good amount of information / data (say 10 to 15 cases). The plant users are the right people to contribute in this matter and suggest them to put their genuine experience about life for belt and other important items like idlers. The belt life information is of practical concern because:

- This helps the plant owners to make more realistic financial layout (expense – income budget) for coming years, for operating the conveying system.

- This enables more correct assessment of operating cost of the system prior to opting for the project.

- The data will be equally useful to conveying system designers and consultants to provide more reliable information to their customers about the system operational cost, minimising the disagreement / discussion-dispute (which is the reason for this thread).

Such life data will have more practical utility (with least confusion) if these are grouped under some headings such as suggested below. Obviously the life data will have a wide variation due to subjectivity to certain points. In spite of this, as an average, the data will still be useful:

1.0 In-plant conveyor

1.1 Coal handling plant in power stations

1.2 Cement plants

1.3 Steel plants

1.4 Ore handling system

1.5 Ports

1.6 Etc.

2.0 Long distance conveyors (cross country conveyors)

The indicated life will be more meaningful if it also mentions few words about quality of plant (below average, average, above average) and yearly operating hours, as an overall picture.

This thread is likely to be of interest to many readers, as it concerns technical / non-technical people, and happens to be live issue in a day to day purchase-sale activity across the world.

Regarding my earlier reply ‘conveying rate 5 times for double the belt width’, is made up of approximately 4 times due to increase in cross section and additional tentatively one time is for higher speed for wider belt, as mentioned therein.

Ishwar Mulani

Author of Book: ‘Engineering Science And Application Design For Belt Conveyors’. Conveyor design basis ISO (thereby book is helpful to design conveyors as per national standards of most of the countries across world). New print Nov., 2012.

Author of Book: ‘Belt Feeder Design And Hopper Bin Silo’

Advisor / Consultant for Bulk Material Handling System & Issues.

Pune, India. Tel.: 0091 (0)20 25871916

Email: www.conveyor.ishwarmulani.comwww.conveyor.ishwarmulani.com ■

I have seen published comments on belt speed vs. belt width. I have even fallen prey to the standards comments. I see no scientific evidence to restrict small belt widths vs. acceptable speeds.

In part this may be due to idler roller diameters. Small width belts are usually fitted with small diameter rollers. Rollers have limited RPM range. If typical idler RPM limit is 700, then belt speed is:

139 mm roll dia. = 5.1 m/s

152 mm " " = 5.6 m/s

178 mm " " = 6.5 m/s

194 mm " " = 7.1 m/s

These are typical rolls. Roll diameter tolerance should be <0.6 mm TIR for sound (pun) operation. There are conveyors operating at 8.5 m/s with 178 mm rolls with special construction. You need to control the TIR value to < 0.4 mm for 95% of rolls. These will still be noisy at higher speeds. If higher speed is required, then added noise and tolerance controls are required.

Again, do not see relevance of belt width and speed limit, other than loading limits and idler RPM. ■