Steel Cord Conveyor Belts Buyer's Checklist: 12 Things to Verify Before You Order

Steel cord conveyor belts are only as safe as the two numbers you can still prove after the belt reaches site: the ST grade that matches your calculated duty tension, and the cord adhesion value that shows the rubber is genuinely holding the cords. Everything else in this checklist supports those two.

We are Ningbo Sinoconve Belt Co., Ltd. (SINOCONVE). We have built belting in Ningbo since 1988, on ten production lines, eight for fabric carcass and two for steel cord. The failures we get called in to look at are rarely manufacturing failures. They are specification failures: a grade copied from an old purchase order, a cover class chosen to shave a few dollars per metre, a splice kit that nobody ordered, a length that was 6 m short of the flight. All of those are decisions made at the desk, not at the press, and all of them are still reversible while the quotation is open.

Send Your Steel Cord Belt Specification for a Factory Quote

So this page is not a product tour. It is the twelve-point verification list we would run ourselves before signing off a purchase order for a long overland or high-tonnage flight: what to ask, what to put in writing, which document proves it, and where the money actually hides. As a conveyor belt manufacturer we see both sides of this table, and honestly the buyer who asks awkward questions in week one is the buyer we still have as a customer in year ten.

One house rule before we start. Every number below is a range we see in normal practice on mining, port, cement and EPC work. Confirm the final construction against the actual duty, the applicable standard and the approved drawing for your project. Nothing here replaces your own tension calculation or your engineer's sign-off.

01Verify the ST Grade Against the Actual Duty, Not the Catalogue

ST grades are quoted as nominal breaking strength across the belt width, from ST630 up through ST1000, ST1250, ST1600, ST2000, ST2500, ST3150 and beyond. The order of magnitude is easy; the choice is not. A belt is selected from the steady-state running tension plus the starting and stopping loads, the slope load, the idler friction and the acceleration of the material, then multiplied by a safety factor. On steel cord, that factor is normally taken as 6.7 or higher in DIN 22101 style calculations, and then divided again by the dynamic splice strength factor, because the splice is the weakest link in the loop.

The trap is a downgrade that looks harmless. If your calculated tension sits at 78% of an ST1600 rating and the project budget is tight, somebody will suggest ST1250 with a thicker cover instead. Thicker covers protect the belt from impact; they do not add a single kilonewton of tensile capacity. The reverse also happens: an oversized grade that is unnecessarily stiff, harder to train, and more punishing on pulleys and on the splice.

A second-order point that separates serious quotations from the rest: the grade on the drawing has to be the grade on the cord purchase. Ask whether the cord was bought to the nominal strength with the standard manufacturing tolerance, and what tolerance the mill certificate allows. Then ask the question suppliers dislike: what tension did you calculate, and which safety factor did you use? A supplier who cannot answer that is passing your risk back to you. Our own production capability note exists for exactly this reason.

What to Ask Before Accepting a Grade

• What is the calculated steady-state belt tension in kN, and the peak starting tension?
• Which safety factor and which splice strength factor were applied, and to which standard?
• Is the take-up travel already checked against the belt elongation at rated tension, not at zero load?
• If the flight may be extended later, is the grade chosen for the future duty or only for today's?
• Can the supplier show the same grade built recently, with the mill certificate and the test records?

02Confirm Width and Length Tolerance in Writing, Not by Assumption

Width sounds trivial and is not. On any industrial conveyor belt, the width at the point of manufacture is measured cold and free of tension. Once the belt is on the structure under load it narrows slightly, and if the top cover is thick and the belt stiff, the difference between a 1,200 mm and a 1,180 mm delivery is visible where the belt meets the skirt rubber and the chute lining. Standard practice for steel cord belts is normally a tolerance in the region of plus or minus one percent on width, with a minimum absolute allowance; write the figure into the purchase order rather than assuming it is understood.

Length tolerance is where real money moves. A tolerance band of a fraction of a percent sounds generous until you are ordering 3,000 m: 0.5% is 15 m, which is either a free spare or a shortfall that forces an extra splice and a second shipment. Agree the tolerance as an absolute figure plus a percentage, agree the temperature and tension at which the belt is measured, and agree whether the length is the ordered length or the delivered length after trimming.

We ask for the take-up travel before quoting, and we ask for it in metres, not "long enough". A steel cord belt elongates very little at working tension, typically a fraction of one percent, so the splice allowances, the take-up and the pulley positions all depend on a length figure that is genuinely agreed. The running direction and the edge type belong on the same approved drawing.

03Check Cord Diameter, Pitch and Construction Against Your Pulley Data

The ST grade tells you how much the belt can pull. The cord design tells you whether it will survive the pulleys it has to bend around. These are separate decisions and they are too often treated as one. A typical construction is a 7x7 or 7x19 or 7x7x7 or 7x37 strand in a brass-plated high-carbon wire, with the number of cords across the width and the spacing between them set by the required strength and by the maximum pitch the splice can handle.

The relationship that matters most in daily operation is between cord diameter and the smallest pulley the belt has to wrap. As a working rule, the minimum recommended pulley diameter is a large multiple of cord diameter, commonly quoted around one hundred to one hundred fifty times; if a drive or snub pulley is smaller, the cords bend tighter than designed and the failure appears as fatigue breaks rather than wear. Typical, confirm against the actual duty, and bring the pulley schedule to the table before you agree the cord size.

Pitch is the second half of the same conversation. Cords spaced too closely make splicing difficult and leave too little rubber between neighbours; cords spaced too widely concentrate load on fewer strands. Where a belt is inspected by a third party, cord position and edge margin are among the first things measured in cross section.

Steel cord wire prepared for stranding.

The Data We Ask For Before Fixing a Cord Design

• Cord construction and nominal diameter, plus the mill certificate for the wire.
• Number of cords across the width and the nominal pitch, with tolerances.
• Distance from the outer cord to the belt edge, and the minimum rubber cover over the top cord.
• Smallest pulley diameter in the system, including snubs and bend pulleys, and the take-up pulley.
• Belt thickness build-up: top cover, cord layer, pulley cover, and the resulting total gauge.

This is also the point at which a sensible buyer checks the belt against the rest of the system. A belt is only half a conveyor: the idlers, pulleys and rollers underneath it decide whether the cords ever see a load they were not designed for. We publish the matching hardware separately, from conveyor pulleys to conveyor rollers, because a cord design agreed without the pulley schedule is a guess. When a drawing reaches our conveyor belt factory, it is checked against that schedule before the cord is released to the line, not after.

One practical aside for EPC packages. Conveyor projects almost always arrive with a stack of auxiliary drives attached, and if the same purchase order covers the crusher drive, the screen or the stacker, it is worth asking one supplier to carry all of it. We are a transmission belt manufacturer as well as a belt builder, so a single shipment and a single inspection file is possible instead of three.

04Ask for the Cord Adhesion Test, Not Just the Tensile Figure

If we could keep only one test from the whole file, it would be cord adhesion. Tensile strength proves the wire; adhesion proves that the belt is a belt and not a bundle of wires sliding through a rubber sleeve. Every steel cord belt is sold on the promise that the rubber grips each cord along its whole length, and every field failure we have been shown in which the belt "suddenly" lost strength had an adhesion problem somewhere in its history.

The usual method is a pull-out test on a cured sample: a single cord is extracted from the rubber and the force required is recorded per millimetre of embedded cord length. What matters is not one number but a set of them, unaged and after accelerated ageing, taken from the actual production run rather than from a separately pressed laboratory plaque. Ageing matters because heat, oxygen and humidity attack the bond between the brass coating and the compound; a healthy fresh value that collapses after ageing tells you the compound is not stabilised.

Tensile and adhesion testing on a cured belt sample.

There is a supply-chain detail behind every test report. Adhesion depends on the cord surface treatment, the rubber compound, and the factory's control of pressure, temperature and time; change the cord supplier mid-project and all three can shift. So look for the cord batch and the compound batch, not only the test value. This same test regime applies in principle to every rubber conveyor belt we make, fabric carcass included, where the equivalent measurement is ply adhesion.

Our own test menu and how samples are drawn are described in the factory testing guide, and if you want to compare what different suppliers will actually run for you, the list of laboratory tests is a useful side-by-side. Send the list to three suppliers and see who answers in full.

05Match the Cover Grade and Thickness to the Material You Actually Carry

Covers are where the cheapest decisions are made and where the biggest bills are created. Two belts can carry identical cord, identical width and identical grade and still differ by a factor of two in service life, because the top cover was a class lower than the rock required. Abrasion classes in DIN 22102 and related standards are separated by measured volume loss, and the gap between a standard class and the best abrasion class is real money in the belt price and much larger money in the replacement cost.

Thickness is the second variable. A steel cord belt usually has a thick top cover to absorb impact and a thinner pulley cover to protect the cords from the pulley side; typical combinations sit around six millimetres over two, eight over three, eight over four, up to ten over four for coarse primary crushed ore. None of those is a recommendation until somebody has looked at the lump size, the drop height and the transfer point design. A one-metre drop of lump ore onto five millimetres of rubber will bruise the cords; the same drop onto a properly designed chute and impact bed is unremarkable.

Cover thickness checked against the approved drawing.

Conditions change the compound, not only the class. Hot clinker or sinter feed needs a heat-resistant compound with a defined temperature ceiling; coal and some ports demand flame-retardant behaviour tested to a recognised method such as ISO 340 in the applicable variant; oil-bearing material, fertiliser and some ores need an oil-resistant cover. Ask any conveyor belt supplier to state the compound family in the offer, and to confirm whether the abrasion class is claimed on an aged or unaged sample. Put the temperature of the material on the enquiry, not the ambient temperature.

Cement and port terminals have their own well-documented patterns, and it helps to compare your duty against plants that already run it. Our notes on cement plant conveying and on mining and quarrying describe where covers fail first when the class is chosen on price.

06Fix the Splice Method, the Splice Kit and the Vulcanising Plan Before You Sign

A steel cord belt is not delivered as a belt; it is delivered as a length of belt with two open ends and an intention. The joint is a stepped vulcanised splice in which the cords are laid parallel, overlapped to a defined pattern and bonded in uncured rubber under heat and pressure. The engineering already happened in step 01, when the dynamic splice strength factor was applied to the grade; now the execution has to match it. A flawless belt with a badly made splice is a belt that will fail at a predictable place.

So decide three things at the quotation stage, not on site. Who makes the joint: the belt maker's own crew, your contractor, or a third-party splicing company. Where the kit comes from: the uncured splice rubber, cover stock and cord ties should come from the belt manufacturer, because the compounds are matched to the belt's own compound. And what the press looks like: platen length long enough to cover the whole splice in one or at most two squeezes, with the working pressure and temperature controlled and recorded. Mechanical fasteners stay in the emergency drawer, because on a cord carcass they cut into the very strands you paid for.

Splice Questions to Close Before the PO

• What is the designed splice length and step pattern, and is it drawn on the approved drawing?
• How many splice kits are included per belt, and how many spare kits are supplied for the same flight?
• Who supplies the press, who supervises the cure, and what is the press platen length?
• Will the press chart (temperature, pressure, time) be handed over as a record?
• Is a destructive or non-destructive check of the first splice specified, and who pays for a re-make?
• Is the splice price inside the belt price or quoted separately, and does it include travel and standby?

07Agree the Roll-Up, Core, Packing and Lifting Specification

Steel cord belting is heavy, and the weight decides how the belt is packed, lifted and unrolled on site. A 1,200 mm wide belt at roughly 20 mm total gauge is in the region of 30 kg per metre, so a 300 m roll runs near nine tonnes before packing. That is a crane lift, not a forklift job. Check the coil mass against the equipment at the port of discharge and at the plant, and against the container limits if the belt ships in a 40 ft high cube.

Small details cause large arguments here. The belt should be wound with the carrying cover facing out, so the cover that matters is not compressed against the core for months in a container. The core must be large enough not to kink a stiff cord carcass, and the outer wrap should keep water and salt air away from the cut ends, where a cord carcass is most vulnerable.

Buyers who order wholesale conveyor belts for stock rather than for one project should specify roll lengths around their own cutting plan, and should say so on the enquiry; a stock roll cut in the wrong place is scrap. If the same container also carries the drive belts for the plant, we ship them together, and as a V-belt manufacturer we can match the shipping marks and the packing list to one file. The full shipping and packaging guide lists the packing options we work to.

08Lock Down Marking, Identification and Traceability

Three years from now someone in your plant will need to know which belt is on that conveyor. The paper will be in an archive, the crate will be gone, and the only witness will be the marking on the belt itself. So the marking is a specification item, not a formality. Ask for the grade, the cord construction, the cover class, the width, the production date or batch and the running direction as an agreed set of characters, printed at an agreed interval along the edge, and ask for it to be legible after a year outdoors.

The roll label is the other half. It should carry the purchase order number, the item line, the length, gross and net mass, the grade and cover class, the splice allowance if any, the batch number and the reference of the certificate that goes with that roll. Photographs of the marking and labels before despatch settle most arguments later. Traceability back to the cord spool and the compound batch is how a real claim is proved or disproved; our approach is described in the note on supplier traceability and inspection records.

Minimum Label and Marking Content

• Edge marking: grade, width, cord construction, cover class, direction of travel, batch or date code.
• Roll label: PO number and line, ordered and delivered length, width, total gauge.
• Roll label: gross and net mass, roll number out of the total, coil core diameter.
• Documents: certificate reference, splice kit reference, packing list entry.
• Handling marks: lift here, do not use cord ends as lifting points, keep dry, this side up.

Marking also has a control function. If the label states the grade and the delivered cross section does not match it, you have found a substitution before the belt is installed instead of after. That is exactly what the quality assurance process is supposed to prevent, and the marking is the evidence that it worked.

09Define the Inspection Plan and the Release Documents Before the Press Starts

By this point you have agreed the grade, the dimensions, the cord, the cover and the splice. Now decide who proves it, with what, and when you pay. The cleanest mechanism is an inspection and test plan attached to the purchase order, listing each check, the reference method, the acceptance value, and whether the buyer or its representative will witness it. Agree that plan before production starts; after the belt is on the roll, everything becomes a negotiation.

The document set that should travel with a steel cord belt is short but specific: cord mill certificate, cord adhesion and full-thickness tensile results for the delivered run, cover compound test values, dimensional record for width, gauge and length, a visual inspection record, and the packing list keyed to the roll labels. If you are buying through a conveyor belt distributor, make the records a condition of the order rather than a courtesy, because in a claim the file is the case.

Third-party inspection is normal on EPC and mining packages, and you should ask for it explicitly if your lender or your owner's engineer requires it. A pre-shipment visit, witnessed sampling, or a full inspection by a recognised agency can all be arranged through the factory; what matters is that the scope, the standard and the fee are agreed before booking, so that the inspector is looking at the belt you specified rather than at a generic checklist. If your project runs on global tender standards, our note on belt standards in global tenders sets out how DIN, ISO, RMA and AS references are usually reconciled in one specification.

Hold Points We Recommend to Buyers

• Before cord release: drawing and construction sheet approved by both sides.
• After curing: dimension check, visual check and sampling for laboratory tests.
• Before packing: sample retention, marking verification, photographs of the belt and the labels.
• Before shipment: document pack complete, splice kits counted, packing list matched to roll labels.
• Before final payment: file accepted, or an agreed deduction held against open items.

One habit is worth copying from experienced buyers: photograph the cross section at the belt edge with a rule in frame. That single image shows the cord pitch, the edge margin and the cover thickness, and it is the fastest way to spot a construction that does not match the drawing.

10Break the Price Down Instead of Comparing One Number

A steel cord conveyor belt price per metre is the least informative number in procurement, because two quotations for the same nominal belt can differ by a third while both are "honest". The gap is normally in the cord, the cover compound, the cover gauge, the number of splices the supplier has assumed, the packing, and the basis of measurement. Compare the line items, not the total, and compare mining belt manufacturers on the same duty sheet.

Steel cord itself is the largest element, and it follows the wire rod market, which is why price validity on a steel cord belt is measured in days rather than months. Cover compound follows polymer and carbon black markets. Beyond materials, the number moves with cover class and gauge, width and total length, edge type, and whether splicing, packing and freight sit inside or outside the quoted figure. Ask for the quote to be split, and ask what is excluded.

Then apply the quality adjustment. A quotation eight percent cheaper because the top cover is two millimetres thinner is not cheaper; it is a shorter interval to the next replacement, plus the labour and downtime of the change. Build one simple figure: expected tonnes carried per dollar of belt cost. Our notes on factory-direct pricing and on comparing supplier quotations go through the same arithmetic from the other side of the table.

11Pin Down MOQ, Lead Time and Payment Terms in the PO Text

Three commercial terms decide whether the technical work above ever reaches site. On quantity, our conveyor belting runs from about 50 m per type, which covers most trial orders and single-flight replacements; where several widths or grades are combined, the minimums are usually assessed per type, so tell the supplier your full basket on the first enquiry rather than in three separate messages. On schedule, our regular lead time is around 30 days and urgent orders can be compressed to roughly 15 to 20 days, with samples in 2 to 5 days, and our current on-time delivery rate is above 95% across more than 1,500 industrial customers. We run ten lines, eight for fabric and two for steel cord, and the steel cord capacity is the constraint that decides a date on a big project.

Ask when the clock starts. Thirty days from deposit and an approved drawing is a different promise from thirty days from today, and drawings often change after the order. Ask what happens if the buyer's approval is late, and if the supplier is late; a modest liquidated damages clause does more for schedule discipline than a verbal promise. On a long flight, ask whether the belt can ship in partial loads, so splicing can start at one end while the rest is in transit.

Our standard payment terms are 30% by T/T with the balance before shipment, or a letter of credit where the buyer prefers one, and we support OEM and ODM work including logo printing and custom widths, thicknesses and colours. Those terms are normal for factories of our size; if a new supplier asks for the full amount before the cord is even ordered, treat that as a signal about their working capital, not as a discount. A factory audit checklist is a cheap way to test the rest.

Milestones to Write Into the Order

• Drawing approval date, and who signs it on each side.
• Production start date and inspection notification period, in working days.
• Ready-for-shipment date with photographs, and the notice period before booking freight.
• Partial shipment and split-delivery rights, and who bears the extra cost.
• Documents required for release of the balance, and the payment trigger wording.
• Delay remedies, and the event that extends the date without penalty.

12Fix the Arrival Inspection and the Claim Window Before the Container Lands

The last of the twelve checks happens on your side of the water, and it belongs in the contract as clearly as the grade. Agree who inspects on arrival, how many days you have to notify a problem, what evidence is required, and what remedy is available: a credit note, a replacement length, or a splicing crew sent to site. A defined claim window from arrival, with photographs and the retained sample as evidence, protects both sides from arguments that surface a year later.

At unloading, count the rolls against the packing list and check the mass, labels and strapping before the crane touches the belt. Look for crushed edges, water staining on the outer wrap, and cut ends left exposed; a cord carcass takes water into the cord layer through an unprotected end, and that damage is not always reversible. Measure the width at two places, and verify the delivered length rather than trusting the label.

Storage rules on site are simple and frequently broken. Keep the rolls flat on timber off the ground, out of standing water and direct sun, with the wrapping intact, and lift the coil with a sling through the core rather than by the belt ends. Give a cold belt time to reach ambient temperature before splicing, because rubber bonds differently when it is cold.

Arrival Sign-Off List

• Roll count, roll numbers and mass against the packing list, photographed.
• Labels legible and matching the PO line by line, including grade and cover class.
• Edge condition, end protection and wrapping integrity recorded before unloading.
• Width checked at two points, and delivered length verified if any doubt exists.
• Document pack filed with the belt, not with the accounts department.
• Claim window and notification contact confirmed in the order acknowledgement.

Run those twelve checks and you will have covered the specification, the hardware, the paperwork, the money and the arrival. Most of them take one email each, and all of them are cheaper than a second shipment. If any point is still open on your enquiry, send us the duty data and the drawing and we will go through it with you line by line before anyone commits to a cord.

Request a Quotation

13Frequently Asked Questions

What ST grade do I need for a long overland flight?

Give us the tonnes per hour, the centre distance, the lift, the belt width, the idler spacing and the pulley diameters, and the grade falls out of the calculation rather than out of a catalogue. As a rough marker, long single flights in mining and port work commonly land between ST1000 and ST2500, and extreme duty goes higher. The calculation, not the range, decides. Our notes on steel cord belts for long-distance mining projects show how the inputs are used.

Which documents should I have before releasing the balance?

A complete set is short: cord mill certificate, cord adhesion and full-thickness tensile results, cover compound values, dimensional record, visual inspection record, packing list keyed to the roll labels, and the declared standards. If your project requires a specific certificate format, agree it at the enquiry stage; the general list is described in the certificate guide, and the common formats are summarised on our frequently asked questions page.

How much extra length should I order for the splices?

Work it out from the splice design, not from habit. Each vulcanised steel cord splice needs enough belt to lay out the full stepped joint plus handling slack at both ends, and on a large joint that is metres, not centimetres. Add the allowance for every joint in the flight, plus a margin for trimming and measurement error, and state the figure in the purchase order. If you want a repair length in store, order it with the belt; a length cut later will not match the same batch.

Why do quotations from different steel cord conveyor belt manufacturers vary so much?

Because they are usually not quoting the same belt. The steel cord conveyor belt price moves with cord grade and source, compound family, abrasion class, cover gauge, edge type, splice kits, packing, and whether freight and insurance are inside the figure. Price validity differs too, since cord follows the wire rod market. Normalise every quotation to one duty sheet and one document list before comparing totals; expect a few percent between good factories, and a much larger gap when something has been quietly removed.

Is a mechanical splice ever acceptable on a steel cord belt conveyor?

As an emergency measure, yes; as a permanent joint on a main flight, no. Fasteners cut into the cords and reduce the strength of the very carcass you paid for, and they give water a path into the cord layer. On a steel cord belt conveyor the designed joint is vulcanised, with a splice length and step pattern matched to the cord pitch. Keep a set of fasteners on site for breakdowns and plan to replace the joint properly at the next opportunity.

How should a steel cord belt be stored before installation?

Flat, dry, shaded and on timber, with the wrapping left on until the belt is needed. Keep the coil on a level surface so the edges do not take the weight, keep it clear of standing water and of anything that can drip oil or solvent onto the cover, and never rest anything on the roll. Avoid prolonged direct sun, because ultraviolet light and ozone harden a rubber cover. Bring the belt to ambient temperature before splicing, and do not lift the coil by the exposed cords.

Can a third party inspect the belt before shipment?

Yes, and on projects with an owner's engineer or a lender it is worth doing. The usual arrangement is a pre-shipment visit with witnessed sampling and a document review, or a full inspection to a recognised agency's scope. Agree who pays the fee, which standard applies and when the visit happens, so that nobody is asked to inspect a belt that has already been packed. See third-party inspection arrangements for how that is normally set up.