Unfortunately your procedures were all wrong. The process should be;

1) Position the belt for splicing/repair in an area where belt clamps can be securely applied

2) Isolate counterweight

3) clamp belt either side of where the splicing is to be done, maybe 5-10 metres either side of the splice area

There are 2 substantive forces at play in a belt system that already has the power isolated, counterweight mass and belt mass. No one should go on or near a belt until the system has been fully isolated and that must include the counterweight. I have seen the results of belt clamps slipping when the counterweight has still been in place and in one instance the belt splicer was almost killed (he lost an arm). Once isolated then you clamp the belt but as near the splice area as possible so that the weight of the belt is not a factor once the belt is cut. Look at you procedures first

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com ■

Review your procedures as Colin says.

Also renovate the clamps. They have taken more than their fair share of wear and tear and possibly the splicing crew had to apply much more pressure to feel secure. That might have dramatically thinned out the covers locally and the slope tension did the rest. Perhaps a case of 'clamp through butter'. ■

Originally Posted by deepakvermaa

Respected Seniors & dear friends,

Few days back we have faced this problem.

"Hot Vulcanising work of on of our damaged ST-1600, 1200mm BW, joint was under progress. To take the joint, following arrangements were made:

1. Belt Clamped near counter weight, on carry and return side.

2. Counter weight lifted till required height to loosen the belt and take Joint.

3. Splicing process was going on at Carry Side around 10-15 Meters from Head Pulley.

Everything was running smooth when we noticed that:

1. THE BELT'S TOP AND BOTTOM RUBBER NEAR BELT CLAMP OF RETURN SIDE was snapped/sliced off like butter. (photo enclosed)

2. The belt moved towards tail pulley as slope was on that side.

3. The portion which has got damaged is neither a Joint nor any repair has been carried out in this area.

4. Prior to this incidence, we have carried out various Joints/Repair in this senario/location, but never faced such damage.

I feel its due to aeging of Conveyor Belt?

I request Senior's please enlight the possible reasons behind such Spurious problem.

Dear Mr.Verma,

Thanks to valuable advice from our senior experts, please take additional precautions as per the procedure as follow :

1. Ensure belt is positioned correctly, where you need to carry out the joint.

2. Ensure LOTO ( Lock-out & Tag-Out ).

3. Please lift the counter weight first, by pre-checked chain blocks or other lifting arrangement, till take-up pulley is free from the belt. This can be checked by rotating the take-up pulley freely by hand.

4. Now only fix the clamps at the desired locations ( typically they are 1) prior to head end bend pulley above take up, 2) head end side of work area and 3) tail end side of joint area). THIS WILL ENSURE THAT WORK SPACE IS ISOLATED FROM THE COUNTER WEIGHT.

5. Remove the damaged joint / portion from mother belt.

6. Overlap the belt where new joint need to be carried out, by further lifting the counter weight.

7. Again tight the tail end side clamp.

8. Draw lines near the clamps by white-chalks and check periodically. This will help to know if at all the clamp slips, since your belt has slope towards tail end. Mostly it won't happen.

Thanks & regards to all,

S.Ganesh ■

Dear Mr.Verma,

Please note 2a& 6a are added below.

1. Ensure belt is positioned correctly, where you need to carry out the joint.

2. Ensure LOTO ( Lock-out & Tag-Out ).

2a. Ask operator to start the belt by giving command, to ensure conveyor is not started and LOTO is carried out on the required machine only.

3. Please lift the counter weight first, by pre-checked chain blocks or other lifting arrangement, till take-up pulley is free from the belt. This can be checked by rotating the take-up pulley freely by hand.

4. Now only fix the clamps at the desired locations ( typically they are 1) prior to head end bend pulley above take up, 2) head end side of work area and 3) tail end side of joint area). THIS WILL ENSURE THAT WORK SPACE IS ISOLATED FROM THE COUNTER WEIGHT.

5. Remove the damaged joint / portion from mother belt.

6. Overlap the belt where new joint need to be carried out, by further lifting the counter weight.

6a. Take-up pulley should be always free from the belt. i.e., that counter weight is not acting on the belt and chain blocks are safely holding the total counterweight.



7. Again tight the tail end side clamp.

8. Draw lines near the clamps by white-chalks and check periodically. This will help to know if at all the clamp slips, since your belt has slope towards tail end. Mostly it won't happen.

Thanks & regards, ■

Originally Posted by sganesh

Dear Mr.Verma,

Please note 2a& 6a are added below.

1. Ensure belt is positioned correctly, where you need to carry out the joint.

2. Ensure LOTO ( Lock-out & Tag-Out ).

2a. Ask operator to start the belt by giving command, to ensure conveyor is not started and LOTO is carried out on the required machine only.

3. Please lift the counter weight first, by pre-checked chain blocks or other lifting arrangement, till take-up pulley is free from the belt. This can be checked by rotating the take-up pulley freely by hand.

4. Now only fix the clamps at the desired locations ( typically they are 1) prior to head end bend pulley above take up, 2) head end side of work area and 3) tail end side of joint area). THIS WILL ENSURE THAT WORK SPACE IS ISOLATED FROM THE COUNTER WEIGHT.

5. Remove the damaged joint / portion from mother belt.

6. Overlap the belt where new joint need to be carried out, by further lifting the counter weight.

6a. Take-up pulley should be always free from the belt. i.e., that counter weight is not acting on the belt and chain blocks are safely holding the total counterweight.



7. Again tight the tail end side clamp.

8. Draw lines near the clamps by white-chalks and check periodically. This will help to know if at all the clamp slips, since your belt has slope towards tail end. Mostly it won't happen.

Thanks & regards,

Dear Ganesh,

The procedure you have worked out and that Mr.Collin suggested is not the same.

Isolation of counterweight does not mean holding the counter weight on the Chain Pulley.

We either give support under counterweight and disconnect the counter weight or transfer the the weight to wire slings.

NEVER ALLOW THE WEIGHT TO BE ON THE CHAIN PULLEY WHICH CAN SLIP. THIS IS A MANDATORY SAFETY REQUIREMENT.

Load on the belt should the weight of belt only.

Rgds,

Narayanan Nalinakshan. ■

in addition to the comments on counterweight isolation and support during this procedure, and the location of the belt clamps in relation to the splice, two other factors should be addressed. first, the splice location should be on the carry side of the conveyor where the belt sees the lowest tension due to belt weight; near the tail pulley for an incline conveyor, near the head pulley for a decline conveyor. second, your belt clamp as shown in the photo does not apply equal pressure across the width of the belt. the clamp should be precambered so that when the full clamping force is applied, the clamp applies an equal pressure to the belt across its width. the clamp should not be made from angle iron which is asymmetric in the clamping direction. an asymmetric section causes the clamp to rotate and results in line contact across the belt width. line contact can cause cable distortion or damage due to high compressive force on the belt. in your case the damage will be at the outer edges of the belt as can be seen in the supplied photo. the clamp should be fabricated from a symmetric section in the clamping direction such as an s-section, w-section or hss-section. again, the section must be precambered.

arthur stack,

solid advantage consultants ■

As Arthur says, the clamps are suspect. Rotation around the shear centre might well exacerbate the line pressure phenomenon. To improve the pressure profile across the belt some crews use Tee sections with a tapering web. It isn't perfect, but it's cheaper and better than the angle cheese cutter illustrated. ■

Originally Posted by johngateley

As Arthur says, the clamps are suspect. Rotation around the shear centre might well exacerbate the line pressure phenomenon. To improve the pressure profile across the belt some crews use Tee sections with a tapering web. It isn't perfect, but it's cheaper and better than the angle cheese cutter illustrated.

The thickness of belt across is not same for used belt.I have seen a few case of belt end damage due to this during clamping and dragging.

But if there is no tension due to any reason on the belt, this will not create problem.

It is advisable to measure the thickness across and take adequate precaution like introducing a suitable thickness ply/rubber sheet at the worn out portion so that clamping pressure across the belt remains same. We have tried this successfully.

Narayanan Nalinakshan. ■

Originally Posted by NarayananNalinakshan

.....

It is advisable to measure the thickness across and take adequate precaution like introducing a suitable thickness ply/rubber sheet at the worn out portion so that clamping pressure across the belt remains same. We have tried this successfully.

Narayanan Nalinakshan.

That's a better idea. It could be universally applied. Thank you. ■

narayanan/john,

i agree that adding belt material at the wear for used belt is a good idea. i would still use a symetric section for the clamping to prevent damage at the belt edges where there may not be protective belt under the clamp. also a line contact on the belt at the clamp could potentially compromise the bond of rubber to steel cords within the conveyor belt. the more area at the clamp the lower the pressure required for clamping and less chance of belt damage. also the clamp should be precambered and the section sized to allow for equal pressure across the belt width, or as close as can reasonably be achieved. ■