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Hi Lyle,

Pipe conveyor is closed but sometimes not totally sealed. It can work because there are a lot of applications in the past. I would like to suggest you to think about SICON conveyor, it is really sealed and more flexible, more info you can find in www.sicon-roulunds.com.

alvali@126.com ■

Of course the cover is obligatory; unless you intend to just recirculate the lime without opening the pipe for loading & discharge. You'll also wet the outside of the belt on the return unless you cover the lot. Then when you lap you'll have ready made wet inside the bore. But if you have an adequately covered gallery why do you need the pipe conveyor? ■

Dear Mr. Banerjee,

The tube cannot be sealed. The seam can/will rotate depending on the belt line forces such that the seam collects water. In such a case, with constant idler agitation the water will seep into the tube in an accelerated manner.

You must cover the conveyor with a rain shroud. ■

John's comment on wetting the bore is appropriate as well unless a belt turnover is utilized. Some pipe belt constructions are not suitable for turnovers, others are. ■

Dear Shri Banerjee,

Pipe conveyor encloses the material mainly to prevent dust emission and retain the bulk material within its body. It will not form water tight seal at the belt edges, because the belt cross section between the idlers will be slightly bulging in configuration. The bulk material will not leak through the minute gap but, liquid can seep through the same, because the penetration / seepage power of liquid is far greater than the bulk material. My suggestion is to put the pipe conveyor in enclosed gallery if you are conveying the material like lime (hygroscopic).

Regards,

Ishwar G Mulani.

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

Author of Book : Belt Feeder Design and Hopper Bin Silo

Advisor / Consultant for Bulk Material Handling System & Issues.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 25871916 ■

It's always a good idea to fix a cover over the top section of a pipe conveyor. Whether you put removable side covers on is a matter of climate conditions and material being carried. In your case having the joint edges wet is sufficient justification for fitting weather proofing. Capillary attraction will cause the water to seep across the whole width of the joint. This dampness will then attract build up of lime on the joint and potential leakage as the build-up increases.

A number of respondents have categorically stated that the joint will leak. This is an interesting point since I do not believe that many people have bothered to undertake any testing.

My studies show that there is certainly no movement of the joint once formed if the correct overlap and belt selection is made. My testing included reducing the tension in the belt and removing idler sets and was undertaken with a loaded belt (Lime stone) through a series of curves. If you skimp on the overlap and choose a very flexible belt it will of course be a different matter but then again it will not only be the water that you have to worry about. ■

Its not just a matter of joint seal integrity. At overlap, a wetted outer face of the inside strip is brought into contact with a possibly dry inner face of the outside strip. There is no drying action as the belt travels to the discharge point where the moisture has partly transferred to the carring side.

Of course after discharge a good Hoesch scraper will clean the belt; to get it ready for another wetting, if it is raining. ■

Perhaps I should have explained that the problem also occurs with the return strand where the joint (overlap) is on the bottom. Water will run down the sides of the pipe to the joint (overlap)and capillary action will take it into the joint (overlap). The damp section will open at the tail and then pass into the loading area attracting lime before the belt closes again.

For those confused by the array of comments....

The outside of the pipe on the carry side remains the outside on the return side so the same surface of belt is being wetted.

A belt turnover would cause both inside and outside surfaces to get wet.

The scraper cleans the inside of the pipe.

The pipe is covered by fixed sheeting and the sides by removable panels. The whole gantry is not enclosed (unless circumstances dictate it necessary)

Carrying lime through a damp windy gantry on a conventional conveyor is not a good idea. ■

Dear John,

I believe your outside on the carry and outside on the return means the belt does not undergoe a turnover action and the seam is pointed downward or earthward. This is so, but, not the only action that can be taken.

Please tell me where the following 5 steps are amiss:

1. Take a piece of paper and print "outside" before forming it into a tube and the print facing earthward on the bottom outside surface oposite the seam.

2. Annotate it over the head pulley with the "outside" faced down contacting the head pulley surface.

3. Annotate it on the return strand leaving the head discharge pulley with the "outside" facing upward away from the earth.

4. Annotate it through a turnover now with the "outside" facing downward/earthward like it is on the carry strand.

5. Now force the paper into a tube, with the seam up, moving on the return with the print "outside" facing, well outside and earthward with the inside dry with or without return product. ■

Dear John:

I do not dispute your capillary observations; however, your statement below causes some disappointment:

“I do not believe that many people have bothered to undertake any testing."

Therefore, they know not.

This surely must refer to the few respondents and not the at-large audience. Since I am one of those few, I take your pointed criticism personally and with prejudice.

As Pocahontas said, "Speak for yourself John". Nobody has questioned your credentials. Such thoughts are a private matter unless it is obvious you know not, but claim the contrary.

It does not even take testing, but simple observation of seam spillage and belt dilation along pipe conveyor path at and between idler sets along carry and return runs.

Further to your sole (pun intended) rewards for controlling the seam position to a stationary point during operation with various curves, without apparent sensing and controlling the seam location, I say is a great analytic skill, luck, or divine intervention. I wonder, but do not question: a) such analytic skills, b) secret knowledge, c) strong potion of luck. It is apparent your are confident in these skills.

I can say CDI did a one year post doc. The PhD/Prof individual had a mastery of FEA, applied and structural mechanics along with the math and validation procedures through FEA to understand this point. The pipe construction was fully decomposed. He could be wrong, but not likely given other PhDs' who reviewed the work and the field observations that followed. I say this to refute your obvious contentions, that other contrary observations to yours are incorrect.

As a side note, when there is a possibility of moisture or other carry surface contamination, special cleaning/drying procedures are used. ■

Dear Mr. John Gateley,

Oh gee dear me!

My apologies John, it was Mr. Dave Morgan I was addressing the last posting to and not yourself.

I got to seeing red, Pocahontas, and could only think of "John" Smith should speak for himself and not for others. I do have an identity crisis on occasion.

I will take what is coming in silence. ■

Larry,

We've all been there & done it ourselves.

Best Regards JG ■

Well I’ve never seen such a deep routed personal attack on anyone. Were you suggesting such a complicated and costly fix to save a few metres of sheeting? These devices are for carrying in both directions which is not what Mr Banerjee was requesting and does not satisfy moisture seeping into the joint (overlap).

Belt turnovers of the conventional form are also used where the product in the top section must not be contaminated by the material being conveyed in the bottom section. Outside then becomes inside. Again hardly relevant for this case however it validates my statement for conventional pipe conveyors “The outside of the pipe on the carry side remains the outside on the return side so the same surface of belt is being wetted.

A belt turnover would cause both inside and outside surfaces to get wet.”

Take umbridge if you may but this is a forum for discussing and clarifying Material Handling problems and topics not slanging matches. There was no personal attack on you so why have you taken such a vicious stance. I think apologies are in order ■

Mr. Morgan:

Deep rooted no. Personal to the point I raised about your accusations which you have not acknowledged.

Your comments were quite emphatic. They suggest contrary comments are not of similar value regarding: a) corkscrewing; b) use of turnovers to keep wetted surface outside on both strands and seams up.

The use of turnovers does not necessarily mean that two products are being conveyed. Since you chose not to accept the alternative of maintaining the dry surface inside the tube and keeping the seam up, no more need be said.

Your comment about the outside surface stays outside for carry and return is only valid if the seam position is reversed without turnovers. The downward seam has lead to spillage.

I do agree about not using personal insinuations. Please reread your comments. You may not have intended to accuse others of incompetence, however, it has that ring. ■

I really struggle to determine the accusations that you are talking about. Have you read my posts with an open mind or are you blinded by some sort of vendetta. Please read them again.

The problem of capillary attraction occurs in gantries regardless of a top or a bottom overlap due to windage hence the need for top and side sheeting in this case. Enough said. ■

I am sorry I raised the issue. Let's move on. No vendetta. I do not know if we have ever met.

I apologize to the forum readers for the untasteful dialog. We can do better. ■

Accepted.

There was no intention to criticise you or any forum member. Perhaps I can choose my words a little more carefully in future. ■