Dear Shri Nilesh Panchal,

In pipe conveyor (tubular belt conveyor), the overlapping edges continuously rub against each other by minute displacement as the belt travels. This is due to the reason that belt cylinder bulges between the rollers and forced to slightly smaller diameter (average) as it passes through belt. So, belt overlapping edges wear is expected. However, degree of wear will depend upon the idler spacing, belt tension and sag.

For edge reconditioning, I can only suggest you to refer to steel cord belt manufacturers and seek their opinion and feasibility for such work. Possibly, they may ask you to send belt to their works for reconditioning. You can send part length (spare length) and see the result and decide subsequent course of action.

Trust the information will be of use to you.

Regards,

Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyors.

Advisor / Consultant for Bulk Material Handling System & Issues.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 25882916 ■

Dear Nilesh,

Conveyor Dynamics, Inc. (CDI) was the consultant involved with the belt under contract with Naveen and Babcock. I am reasonably familiar with the initial installation.

Unfortunately, we gave the commissioning to Mr. Phil Staples due to our difficult schedule on other projects at the time. I would like to re-establish a working arrangement to aid in your request.

CDI can do all you require:

1. We are technically competent to carry out an investigation on you problems with regard to belt physics, quality, flaws generated from operation; life expectancy.

2. Naveen and Mr.Phil Staples selected Taeryuk for cost reasons. CDI formed a test plan and test rig concept, to evaluate Taeryuk construction and potential for pipe conveyor service. They had never built a pipe conveyor prior to Birla Copper's installation. The test rig was contracted and carried out by Wits Univ. in RSA.

3. CDI has access to the best condition monitoring and other data acquisition equipment and lab tests for steel cord belt construction. We have already completed test work on other projects in India.

4. Future life prediction requires many points of consideration and evaluation. This cannot be accomplished from an office chair.

5. Normal steel cord belt life is selected with respect to operator's design criteria. If you want 15 years, and state so, then you get 15 years. If you don't state so, then suppliers feel compelled to compete to get the job at lowest cost and you may get an inferior product. You need to have an expert, competent is such matters, survey the installation and report on all aspects that affect its life, performance related to your expectancy. If you wish a higher level of performance, this may be achieved. The benefits and costs must be presented.

We would appreciate the opportunity to serve your interests.

Lawrence Nordell

President

Conveyor Dynamics, Inc.

email: nordell@conveyor-dynamics.com

website: www.conveyor-dynamics.com

phone: USA 360-671-2200

fax: 360-671-8450 ■

Dear Nilesh Panchal:

This sounds as if you should get the interested parties involved (Taeryuk and Mr. Staples) with the possibility of CDI as a paid consultant/troubleshooter.

Two questions that immediatel come to mind are:

1) Why are the belt edges rubbing against structure - or am I misunderstanding you? The edges of a pipe belt (or any other type of belt) should never touch the structure of the conveyor, as you will experience damage to both the belt edge and (more importantly?) the belt will saw through the supports.

2) Why are the belt edges rubbing against guide rollers? Guide rollers, if used on a pipe belt, should only come into contact with the bottom cover of the belt - unless you are using side guide rollers at the loading and discharge zones where the belt is open. If this is the case, prevent belt wear by correcting the training - guide rollers, if used as a mistraining stop-gap measure, on make the mistraining worse as they provide a further braking action on the side of the belt that is already too far over.

Although Mr. Nordell was a little indelicate in his comments, he is correct in stating that properly engineered systems and belts are more cost effective than their low capital cost alternatives. Generally, the higher capital cost syetems and belts are the least costly on a tonnage conveyed basis - not even counting lost production and down-time costs.

Likewise, an effective PM programme pays for itself very quickly, if downtime and lost material costs are factored in.

Regards, ■

Dear Nilesh Panchal:

Sorry - forgot to answer your question on steel cord belt life.

As you might expect, this is very dependent on both the quality of the belt , the system, and the PM regimen. I've known systems where the steel cord belt needs to be replaced every two years (and the user is happy with that longevity) and I also know of systems with a thirty year and counting life span.

For operations such as you describe, I would expect a belt life of 10-14 years, assuming a good quality belt, a propertly designed & installed conveyor system, and an adequate PM program. If any of these three parameters is questionable, expect a belt life between three and ten years. If two out of three is questionable, expect a belt life of one to six years. If all three are questionable, be happy with whatever you get.

Regards, ■

Dear Mr. Nilesh Panchal,

From your points:

1. I would expect the belt to run differently in no-load conditions than with loaded conditions. The load places more force against the idlers and will, therefore be more sensitive to idler positioning, wear, material build-up, and bearing failures. In non-load conditions, the belt may float because it does not have enough contact with the idlers. This can give other problems and highlights the necessity of both good design and good components.

2. The different rotation range will be bulk density and speed related. This is an extension of the first point (i.e. the belt is doing what the system is telling it to).

3. Presumably, the belt edge getting entangled on the idlers during positive rotation means that the exposed edge is folding back on itself as the belt tries to rotate. This suggests that you may have a tension problem (insufficient or excessive take-up pressure). You may also have an idler alignment problem.

4. The increase in horsepower and speed, without a full system analysis and correction, would tend to exacerbate the conditions.

5. The belt running off the discharge pulley while unloaded and staying centered while loaded also suggests a tensioning problem.

6. Using guide idlers to try to muscle the belt back into the center is counterproductive (although it will help prevent immediate damage to the structure ? I?ve seen more than one belt edge saw through support steel ? the guides place a braking action on the belt edge, which only forces the belt further over on that side, albeit downstream). Depending on the length of your transition zone, one or more self-aligning roller sets may be more effective for a short-term remedy.

7. If the belt edges are contacting each other during the pipe formation stage, your forming idlers are not properly setup.

8. Poor PM and belt mis-tracking can take time to manifest themselves into recognizable problems. Unfortunately even with a good PM programme, it is easy for conditions to slowly change until a problem develops. Also, changes in the system can create unexpected negative results.

RECOMMENDATION: Have the system analyzed by a company you have confidence in. After the analysis, weigh the recommendations and react accordingly. The belt manufacturers and system designers are normally a good starting place. An independent company may be more productive, but will be more expensive. (I?m not trying to get work ? I have no time available for the foreseeable future. You should consider companies such as CDI )

Regards, ■