Transfer towers are definitely buildings and must be designed according to the prevailing national standards. Conveyor trestles and such are also buildings. When a conveyor runs over a railway line the bridge design standards apply. Etc. There is nothing special about conveyors, nothing at all. They must meet local scrutiny. If spillage depth is the point of contention consider the floors laden with spillage up to the return strand, and full width. Also read what Martins' Foundations has to say. Structures aside, make sure you comply with the fire and safety business. They should determine the spans. ■

In addition to John's comments. For loading you must allow for any transfer chute work to be fully filled with the product being conveyed in case of a plugged chute. ■

Hello,

The belt conveyor when over-head, is installed on / in super structure (gantry, gallery, trestles, transfer houses).

The belt conveyor is mechanical equipment, and it includes all mechanical, including supporting frame for mechanical items. This supporting frame is called ‘conveyor frame’ (say chassis). Thus, name belt conveyor includes belt, pulleys, idlers, scrapers, drive unit, stringer, stands, head terminal, tail terminal, bend pulley support, take-up, skirt board, discharge end hood, spout, etc.

The belt conveyor as stated above is supported by super structure. The conveyor super structure has following 3 functions:

1) Provide supporting floor to conveyor.

2) Protect conveyor from environment (sunlight, rain, stormy wind, snow, etc. as applicable).

3) Provide access, floor, etc. for regular operation, inspection and maintenance of conveyor.

The belt conveyor designer (mechanical) decides the conveyor arrangement basic drg including space around it, super structure dimensional feature in context of operation, maintenance, etc. He also decides trestle type / location in consultation with structural engineer. The conveyor designer also depict cable place / space, in consultation with electrical engineer. Then this basic drg copy goes to structural engineer, electrical engineer and civil engineer. The conveyor designer inform load / forces acting at all footings of conveyor frame. He also informs the stage - 1 design output and conveyor’s important technical features along with the basic drawing. The loads / forces at each footing comprise of:

- Horizontal force - X along conveyor length, toward head or tail. Mostly this will constitute shear force at footing interface.

- Horizontal force - Y along conveyor width. Mostly this will constitute shear force at footing interface.

- Vertical force - Z, up or down. Mostly this will constitute compressive or tensile load.

The conveyor designer also inform live load on floor / walkway depending upon the conveyor components heaviness, etc.

Thus now structural designer has conveyor basic drg showing conveyor and super structure; and also the load applied by conveyor, on to super structure.

The structural designer designs the structure, as per the well known and established design procedure, taking care of the equipment load, wind load, earth-quake, erection load, applicable statutory codes and standards in the country of installation, etc. After completing the structural design, the designer informs to the mechanical designer, the rectification necessary in the conveyor arrangement drg made earlier (mechanical), which becomes an agreed basic drg by all concerned. Similarly, comment from electrical engineer and civil engineer is also taken care in basic arrangement drg.

The structural dept creates structural arrangement drgs and manufacturing drgs in conformity with agreed specification, and applicable standards and to provide sound supporting structure for the conveyor. The above narration mentions straight line interaction between mechanical, structural, electrical and civil, but in reality it is to and fro, as an ongoing process during initial phase of project implementation.

I think, the above back ground information will possibly be of use for the structural designers and others to put forward their technical or non-technical queries in the forum and make this topic lively.

Ishwar G. Mulani

Author of Book : Engineering Science And Application Design For Belt Conveyors (new print November, 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: conveyor.ishwar.mulani@gmail.com

Website: www.conveyor.ishwarmulani.com ■

Hello,

The belt conveyor when over-head, is installed on / in super structure (gantry, gallery, trestles, transfer houses).

The belt conveyor is mechanical equipment, and it includes all mechanical, including supporting frame for mechanical items. This supporting frame is called ‘conveyor frame’ (say chassis). Thus, name belt conveyor includes belt, pulleys, idlers, scrapers, drive unit, stringer, stands, head terminal, tail terminal, bend pulley support, take-up, skirt board, discharge end hood, spout, etc.

The over-head belt conveyor as stated above is supported by super structure. The conveyor super structure has following 3 functions:

1) Provide supporting floor to conveyor.

2) Protect conveyor from environment (sunlight, rain, stormy wind, snow, etc. as applicable).

3) Provide access, floor, etc. for regular operation, inspection and maintenance of conveyor.

The belt conveyor designer (mechanical) decides the conveyor arrangement basic drg including space around it, super structure dimensional feature in context of operation, maintenance, etc. He also decides trestle type / location in consultation with structural engineer. The conveyor designer also depict cable place / space, in consultation with electrical engineer. Then this basic drg copy goes to structural engineer, electrical engineer and civil engineer. The conveyor designer inform load / forces acting at all footings of conveyor frame. He also informs the stage - 1 design output and conveyor’s important technical features along with the drawing. The loads / forces at each footing comprise of:

- Horizontal force - X along conveyor length, toward head or tail. Mostly this will constitute shear force at footing interface.

- Horizontal force - Y along conveyor width. Mostly this will constitute shear force at footing interface.

- Vertical force - Z, up or down. Mostly this will constitute compressive or tensile load.

The conveyor designer also inform live load on floor / walkway depending upon the conveyor components heaviness, etc.

Thus now structural designer has conveyor basic drg showing conveyor and super structure; and also the load applied by conveyor, on to super structure.

The structural designer designs the structure, as per the well known and established design procedure, taking care of the equipment load, wind load, earth-quake, erection load, applicable codes and standards in the country of installation, etc. If the country has own design code for structural design, then compliance to it is a statutory requirement, as it concerns with the safety of people, and it will also have relevance to plant insurance. After completing the structural design, the designer informs to the mechanical designer, the rectification necessary in the conveyor arrangement drg made earlier (mechanical), which becomes an agreed basic drg by all concerned. Similarly, comment from electrical engineer and civil engineer is also taken care in basic arrangement drg.

The structural dept creates structural arrangement drgs and manufacturing drgs in conformity with agreed specification, and applicable standards and to provide sound supporting structure for the conveyor. The above narration mentions straight line interaction between mechanical, structural, electrical and civil, but in reality it is to and fro, as an ongoing process during initial phase of project implementation.

I think, the above back ground information will possibly be of use for the structural designers and others to put forward their technical or non-technical queries in the forum and make this topic lively.

Ishwar G. Mulani

Author of Book : Engineering Science And Application Design For Belt Conveyors (new print November, 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: conveyor.ishwar.mulani@gmail.com

Website: www.conveyor.ishwarmulani.com ■

There is an old German saying that you should first ask the electrical discipline where the cables should run and then design the conveyor to run alongside. It's not as strange as it might sound. Electrics usually push their nose in at the last minute and try to change everything. If you get them to commit at the beginning it is harder for them to change later on. I have been seriously asked to consider reorienting large motors because they were obstructing a lamppost or other fittings. This, when the reclaimer was already built and commissioned.

A word on structural detail. Leave it till last. If somebody has undersized a water pipe and mentioned it midway through then the structural guys jump on the bandwaggon and do a complete analysis at great expense. ■

As I know usually there is 2 criteria for designing equipment and steel structure: allowable stress and allowable deflection.

Most belt conveyors gallery check for the allowable deflection not for stress. It means that when you apply every load on structure, stresses are low but you can not reduce size of structure beams because of maximum deflection of gallery at mid span.

As criteria for allowable stress is yield stress, for allowable deflection usually is the ratio of support span. I myself search a little for the allowable ratio especially for belt conveyors but I have not found anything.

However in designing some equipments we use l/200 (l=support span) as allowable deflection. ■

First, I think you mean 1/2000. No structure would be designed for 1/200.

Second, all of our structures, whether ground based or elevated are stressed first, analyzed for wind and harmonics second, and last for deflection and mainly if in client design criteria. There are reasons to check deflection, if moving machinery is to be considered.

In the past, deflection has been a check on stress. Usually, the designs are dumbed down to allow simple analytic techniques. Today, with reasonable parametric models, FEA codes can do quick work. This is especially true if you use a stick model such as RISA 3D, Pro-Steel, STAAD or the like.

For all large systems with many repeating structures, we use ANSYS. ANSYS can highlight special stress zones that are not identified in the stick analyses. ANSYS is very helpful in reinforcing junctions, corners, and complicated connections including expansion joints.

One point most engineers miss is to load the belt to its edges at a steady-state condition to stress the structures. ■

Originally Posted by nordell

First, I think you mean 1/2000. No structure would be designed for 1/200.

Second, all of our structures, whether ground based or elevated are stressed first, analyzed for wind and harmonics second, and last for deflection and mainly if in client design criteria. There are reasons to check deflection, if moving machinery is to be considered.

In the past, deflection has been a check on stress. Usually, the designs are dumbed down to allow simple analytic techniques. Today, with reasonable parametric models, FEA codes can do quick work. This is especially true if you use a stick model such as RISA 3D, Pro-Steel, STAAD or the like.

For all large systems with many repeating structures, we use ANSYS. ANSYS can highlight special stress zones that are not identified in the stick analyses. ANSYS is very helpful in reinforcing junctions, corners, and complicated connections including expansion joints.

One point most engineers miss is to load the belt to its edges at a steady-state condition to stress the structures.

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OLD CODES use to apply 1/360. Most use 1/500 today for major structures.

When we used elevated structures, our designs often do not have walkways, but, use self-powered maintenance trolleys. As such, not walkway loads. A dual sided walkway can weigh as much as an elevated truss with a 30 m span. For elevated structures over 700 m, it makes sense to use the powered trolley vs. walkways. ■

Good conveyor system need good conveyor components, Jienasi can supply excellent conveyor idler/roller for different standard such as DIN,CEMA etc.,for more information, please log on our website: http://www.jienasi.com for checking..

Best Regards

Steven ■

With any conveyor structure you need to focus on the critical areas which are known by your experienced and respectable maintenance teams. Before going into any new designs, get as much input from the floor and then do an assessment/analysis before going out for tenders.

These are some key factors on any or all conveyor structure designs:

- Stay away from high transfer towers

- Make sure you know and understand where to install your scrapers(belt cleaners), before designing your chutes - Spillage control is key to production

- Stay away from impact beds - they can only handle low speed conveyor belts

- Use high quality inline retractable impact idler frames - (I have a simple design guaranteed to last at least 5 years and longer, which increases impact idler and belt life)

- Focus on good quality rubber impact idlers - Refer to Lorbrand designs

- Decrease idler spacing, which is critical in idler life

- Install light weight covers over your wing idlers, to cover the exposed areas against all weather conditions. (Think of it as having your idlers stores in a well kept warehouse)

- Have a strong super structure to last as long as possible. (H- and I-beam structures recommended)

- Use multiple tail-end scraper to eliminate all tail pulley spillages and wear

Do your homework before going out to all these expensive engineering companies and tell them exactly what you want and expect from them. Make your task team(team of maintenance experts, Millwright, Electrician, Fitter, Boilermaker, Supervisor, Production Supervisor and an experienced Operator) part of the design process from day 1.

This is never recommended by companies, but if you think about it... the more your people know, the better they will maintain and operate your assets and equipment and therefor you will get the most out of everything, a highly motivated team with endless knowledge of your company and its goals/output. ■

Conveyor Dynamics, Inc. (CDI) practices the following design criteria not mentioned in the above comments:

1. Conveyor cross-section is loaded edge-to-edge with maximum acceptable surcharge angle for each span group whether ground based or elevated. This can increase the load stress by 50%, but, is taken as a momentary condition

2. Cross-section has sufficient crew clearance for carry roll change-out

3. Cross-section is fitted with ability to increase belt size by one increment and still allow proper belt wander clearance (125 mm)

4. Minimize shelves that collect material and moisture

5. All steel components are checked for modal frequency coupling to eliminate sympathetic vibrations - especially true for overland conveyor designs

6. Handling mass of components, during erection

7. Nesting of components for optimized shipping shapes in trucks/cargo containers

8. Warpage during galvanizing and its effect on structural assembly and belt tracking

9. Difference in fabrication of hot rolled vs. sheet metal shapes and their field assemblies

10. Jigging structural members for control of field fitting, conveyor alignment, and belt tracking ■

Originally Posted by nordell

-------------------------------------------------------------------------------------------

OLD CODES use to apply 1/360. Most use 1/500 today for major structures.

When we used elevated structures, our designs often do not have walkways, but, use self-powered maintenance trolleys. As such, not walkway loads. A dual sided walkway can weigh as much as an elevated truss with a 30 m span. For elevated structures over 700 m, it makes sense to use the powered trolley vs. walkways.

You just inspired me to study Structural Engineering. I would love to work for your company one day. You sound like a great boss that is passionate about what you represent.

It feels great just to be part of this Portal. ■

We have engineered and supplied conveyors, especially our sandwich belt high angle conveyors, all over the world. We have designed to the many various standards which define the various loads and load combinations and the corresponding stress allowables. Like other USA companies, pursuant to our in-house standards, we design largely according to the AISC manual and the key to its applicability for conveyors is in defining the controlling loading conditions. Because we also do much engineering support of of power plant maintenance contractors and design of hoisting and rigging systems we have adapted the rigging criteria to our design of conveyors. We call this rigging criteria and for this we use the same design basis that is used by Crosby McKissik and others in rating their lifting equipment and components, that is Fa & Fb (primary) = Fult/5, and Fv (shear) = Fult/10. Fult is the ultimate rupture stress in a standard tensile stress to rupture. This criteria is approximately equivalent to multiplying the loads by 1.8 then using AISC as the basis for design. We apply the rigging criteria locally at framing that supports pulleys, drives, take-up, items that are more subject to impact and adjustments, etc. I believe that we are unique in this approach.

Joe Dos Santos ■

Originally Posted by nordell

First, I think you mean 1/2000. No structure would be designed for 1/200.

Second, all of our structures, whether ground based or elevated are stressed first, analyzed for wind and harmonics second, and last for deflection and mainly if in client design criteria. There are reasons to check deflection, if moving machinery is to be considered.

In the past, deflection has been a check on stress. Usually, the designs are dumbed down to allow simple analytic techniques. Today, with reasonable parametric models, FEA codes can do quick work. This is especially true if you use a stick model such as RISA 3D, Pro-Steel, STAAD or the like.

For all large systems with many repeating structures, we use ANSYS. ANSYS can highlight special stress zones that are not identified in the stick analyses. ANSYS is very helpful in reinforcing junctions, corners, and complicated connections including expansion joints.

One point most engineers miss is to load the belt to its edges at a steady-state condition to stress the structures.

With all my respect nordell, I should say 1/200 deflection is a defensible criteria for designing structures like stringer, truss also for other simple structures like roof sandwich panel. For more please check following BeltCon article,there the 1/300 as a allowable deflection has been selected for design criteria

http://www.beltcon.org.za/docs/b1405.pdf ■

Originally Posted by AiDiN

With all my respect nordell, I should say 1/200 deflection is a defensible criteria for designing structures like stringer, truss also for other simple structures like roof sandwich panel. For more please check following BeltCon article,there the 1/300 as a allowable deflection has been selected for design criteria

http://www.beltcon.org.za/docs/b1405.pdf

I may have been a little hasty in staking 1/2000 deflection, which is often cited for rotating shafts and vibration control at higher equipment speeds. However, the AISI standard and USB code standards did limit structural member deflections to 1/360 and now some modern standards call for 1/500. When we design overland conveyor structures, used to support rotating equipment, resonance must be addressed. Vibration of belt, idlers, idler supports, stringers, and main support structures are all evaluated so they do not couple with the same resonant frequencies.

I admit CDI has never studied 1/200 for its benefits in steel compliance or for minimizing steel mass. To CDI, this means that the 1/200 members do not resist vibration but may add to any vibration energy excitation and lower the vibration modal frequencies, which in turn may lead to trouble.

Our sheet metal and idler support members also double as structural reinforcements.

Would you care to share a beneficial example of this concept - where 1/200 is used and why? Is this a cost saving approach?

I am aware of structures resonating and causing product coalesce on the belt with poor idler frame compliance and stringer compliance. There is ample evidence in Australian, Chile, China, and South Africa of deflection compliance problems with conveyors over 500 m length with higher belt speeds (>5 m/s). We have not looked at the deflection ratio of our designs, but, since this is becoming a hot topic, it should be a criteria. A paper is to be presented at a coming Beltcon session by CDI on "bunching", which I call coalesce of ore on belt. This is akin to volcanoes. pulling material/product from the outer lower region and circulating the product horizontally and then vertically up through a center path of the cone of the volcano to discharge the product at its peak and rill down the formed cone/mound outer surface and start the cycle over. I have also witnessed this phenomenon in a shop where vibration was induced on a belt with ore for the study of vibration actions. ■

Dear Mr.Nordell,

would you please introduce us the number of these standards? these are exclusively for belt conveyors or general steel structures?

Originally Posted by nordell

I may have been a little hasty in staking 1/2000 deflection, which is often cited for rotating shafts and vibration control at higher equipment speeds. However, the AISI standard and USB code standards did limit structural member deflections to 1/360 and now some modern standards call for 1/500. When we design overland conveyor structures, used to support rotating equipment, resonance must be addressed. Vibration of belt, idlers, idler supports, stringers, and main support structures are all evaluated so they do not couple with the same resonant frequencies.

■

All the national standards in force should be applied, ISO usually take overall precedence although these can be overridden locally if there is improvement etc. Application covers fire protection, structural integrity and general safety matters.

There are outstanding flaws in interpreting the precedences e.g. most countries fire regulations require provision for safe exit at about 50m intervals. So that should be a limiting factor in galleries: sometimes it is and sometimes it isn't. How is a travelling maintenance trolley evacuated?

Some major European contractors insist that their floor spillage depth is less than half that which Martins Foundations shows as photographic evidence. Their depth figure is often accepted by the customer because it is more profitable and there is no official standard. That's almost what I was trying to say: there is no useful official standard and that is what makes it so much fun! ■

There is not one answer to this it will depend on application, building codes, spans, loading conditions (live load only or dead and live ect) the allowable deflection can 1/240, 1/360, 1/500 etc for example in buildings where plaster is present 1/360 is generally used to prevent cracking. The specific case must be examined. ■