1
A melting unit
Bags cannot be decanted, chipped or poured like drums. The unit is charged whole or as a stripped block and melted down. Without a melter the cargo cannot be put to use.
Both are quoted simply as "bags", and they are handled completely differently at destination. Which of the two is wanted is a line in the enquiry, not a detail to be settled after the container arrives.
A woven polypropylene bulk bag with an inner liner, filled with hot bitumen and allowed to solidify — in a cooling tunnel, in a water bath, or simply standing until the block has set. At destination the outer bag and the liner are cut away and the block of bitumen is charged into the melter. The packaging is waste — less waste than a steel drum, but waste all the same, and someone has to strip it. Where the block was cooled in a water bath, ask how the unit was dried before it was closed, because water trapped against the block goes into the melter with the binder.
A bag made from a film that is designed to melt into the binder along with its contents. The whole unit is charged into the melting unit and nothing is stripped, nothing is disposed of and nobody handles hot material to open a package. Name this version explicitly if it is the one you want, because an order that says only "bags" can be filled with either.
A meltable film becomes part of the binder. Ask the producer what the film is, at what proportion of the charge it enters, and whether it affects any specification line your project actually tests. Solubility in trichloroethylene to ASTM D2042 is the one to check — polyolefin films are not necessarily soluble in that solvent, and a minimum of 99.0 % solubility is a hard limit in ASTM D946 for penetration grades and in ASTM D312 for oxidized roofing asphalt, both measured by ASTM D2042, while EN 12591 sets the same 99.0 % minimum by its own method, EN 12592. Whichever family the binder belongs to, the line is on the certificate. This is a question to answer before shipment rather than a reason to avoid meltable bags, and it is answered in writing by the producer or it is not answered at all.
A bag is not a container in the sense a drum is. It is a fabric skin around a block of bitumen that was cast inside it, and almost every practical question about bags — melting, deformation, lifting, waste, storage life — traces back to how the two layers were chosen.
The outer is a flexible intermediate bulk container: woven polypropylene tape fabric, either circular-woven as a tube or sewn from panels, with four lifting loops at the corners. That fabric is the only load path the unit has. A cast block of bitumen has no lifting points of its own, so everything about whether a one-tonne unit can be moved at any stage of its life is a property of the bag rather than of the cargo.
Solid bitumen at ambient temperature is not classified as a dangerous good for transport, so a UN performance-certified bag is not normally required. The reference to name in an enquiry is ISO 21898, which covers flexible intermediate bulk containers for non-dangerous goods. Two figures follow from the design type and neither can be assumed: the safe working load, and the safety factor between that load and the load the design type was tested to. Ratios of 5:1 for single-trip designs and 6:1 for multi-trip designs are the common commercial designations rather than requirements a buyer can take for granted. A bitumen bag is single-trip by nature, because the outer never comes back, and that is worth saying out loud in the order so nobody prices a multi-trip bag into a one-way shipment or the reverse.
The other fabric question is ultraviolet. Polypropylene degrades under sunlight, and UV-stabilised fabric is an option rather than a default. If the bags are going into a melter within days of discharge the point is academic. If they are going to stand in an open yard, the UV answer decides whether the unit is still liftable when it is finally needed, and it is the single most useful thing to ask about the fabric. Fabric weight in grams per square metre and loop construction — cross-corner or corner-sewn — are legitimate lines in the enquiry for the same reason.
Binder is cast into the bag at roughly 140 to 160 °C, the same temperature range at which drums are filled. Polypropylene melts at about 160 to 165 °C and softens well below that. Pour bitumen at 150 °C directly onto woven polypropylene and the fabric is at or near its own softening range at the moment of contact. The outer therefore cannot be the surface the hot binder touches, and that is the liner's first job: it is a thermal barrier during filling, not a convenience.
It has two more. It is a release surface — a block of bitumen bonds to whatever it cooled against, and the liner is what allows the set block to be separated from the bag rather than dug out of it. And it is a contamination barrier, keeping dust and moisture off the block in storage and keeping fabric fibres out of the melter charge.
Those are opposite requirements and one polymer cannot satisfy both. It follows that a meltable-film unit cannot simply be a lined bag with a cheaper liner. Something in the filling process has to give — a lower casting temperature, a heavier film, or a two-layer construction in which a meltable inner is shielded by the outer while the binder is poured. Ask how the meltable bag is filled. The answer tells you where the film actually is, what temperature it has already seen, and therefore how confident you can be that it will behave in your melter.
Film melting range also sets the demand you place on the melting unit. Polyethylene-based films melt in the region of 105 to 115 °C for low-density grades and 125 to 135 °C for high-density grades — general published values for those polymers, well below the temperature a bitumen melter operates at. But melting and dispersing are not the same operation. A film that liquefies at 110 °C still has to be sheared and distributed through a tonne of binder, and on a static, unagitated unit it can survive as a visible residue floating on the charge. Whether the melting unit circulates or agitates is a fair question to put alongside the film question, and it is worth asking the producer which melter types the film has already been run in.
Nor is melting the same as dissolving, which is the point behind the solubility question above. A polyolefin can be entirely liquid at melter temperature and still not be soluble in trichloroethylene at the conditions of ASTM D2042, so the specification line and the plant behaviour are two separate matters and both have to be settled.
There is no need to accept a general reassurance about how little film enters the binder. Ask for the film mass per bag in kilograms and divide it by the 1,000 kg net. That gives the dosage as a mass fraction of the charge directly: 1 kg of film per bag is 0.1 % of the binder, 3 kg is 0.3 %. Those are illustrations of the arithmetic and not figures for any particular bag — get the mass from the producer and do the division. Then put the resulting fraction, with the polymer identified, to whoever approved the binder for the project, and get the acceptance in writing rather than assuming it.
Using the density reference used across this site — about 0.952 t/m³ at 150 °C and about 1.03 t/m³ cold, set out on the tonnage and volume conversions page — one tonne of binder occupies roughly 1.05 m³ hot and about 0.97 m³ cold. The block therefore contracts by something like 7 to 8 % in volume as it sets.
Two consequences follow, and both surprise buyers. The bag is never tight: the fabric ends up slack around a block smaller than the bag was when it was filled, usually with a dished or hollow top. A bag that looks under-filled is normal, which is exactly why net weight has to be established by weighing and never by appearance. And cooling is slow. A one-tonne block presents on the order of 6 m² of surface per cubic metre of material against roughly 10 m² for a 210 litre drum, so it sheds heat far less readily per tonne. A bag stuffed into a container before its core has set will deform under the tier above it whatever the restraint, so how long bags stand between filling and stuffing is a real question, not a procedural one.
Bags are normally palletised for export, which is what allows a forklift to take the unit from below when the loops are not usable and what keeps the block off a container floor that will sweat in transit. Pallet timber is wood packaging material under ISPM 15 and must be heat treated or fumigated and carry the IPPC mark; untreated dunnage triggers fumigation, detention, re-export or destruction at destination at the shipper's cost. The pallet also consumes container height, and that is part of why a third tier of bags is not available in a 20-foot box.
A jumbo bag has five or six components and each one decides something at the far end. This table is written as an enquiry checklist: the right-hand column is what belongs in the order so that the bag that arrives is the bag that was priced.
| Part of the bag | Typical material | What it does | Why it matters at destination | What to state in the enquiry |
|---|---|---|---|---|
| Outer bag | Woven polypropylene tape fabric, circular-woven or sewn from panels | Contains and carries the cast block; it is the only structure the unit has | Governs whether the unit can be lifted at all after storage or a rough inland leg | Safe working load, the safety-factor ratio the design type carries, and whether the fabric is UV-stabilised |
| Lifting loops | Woven polypropylene webbing, four corner loops | The sole load path into the block | A degraded or torn loop makes a one-tonne unit immovable without a crane and slings | Loop configuration, loop length, and the load they are rated to carry |
| Release liner (lined jumbo bag) | Film or coated liner whose melting range sits above the 140 to 160 °C fill temperature | Takes the heat of the pour, gives the set block a release surface, keeps dust and moisture out | It survived the fill, so it survives the melter — it has to be stripped and disposed of | That the bag is the lined type, and who strips and disposes of liner and outer |
| Meltable film (poly bag) | Film whose melting range sits below melter temperature so it enters the binder | Replaces both the liner and the strip-off step | Nothing is stripped and nothing is disposed of; a small mass of polymer joins the charge | Film identity, film mass per bag in kilograms, and the effect on solubility to ASTM D2042 |
| Top closure or filling spout | Woven polypropylene, tied or heat-sealed after filling | Closes the unit once the binder is in and has set | An open or failed top lets water and dust sit in the dished block top and go into the melter with the binder | Closure type, and whether the top is sealed or tied |
| Pallet | Timber, occasionally plastic | Allows the unit to be taken from below as well as by the loops, and keeps the block off the container floor | Timber is wood packaging under ISPM 15 and must carry the IPPC mark or the container is held | Whether bags are palletised, the pallet footprint, and ISPM 15 treatment evidence |
| Markings | Printed or labelled on the outer fabric | Identifies grade, batch number, net weight and production date | A bag whose marking has weathered off cannot be matched to a Certificate of Analysis, and fabric marking weathers faster than drum stencilling | That grade, batch number, net weight and production date appear on every unit |
Freight is charged by the container rather than by the tonne, so cargo per container drives landed cost more than the packing price itself does. That single fact, not the price of the bag or the drum, is what the table below turns on.
| Packing | Net per unit | Units per 20' FCL | Net cargo | Containers per 1,000 MT | Waste to dispose of |
|---|---|---|---|---|---|
| Jumbo / poly bag | 1 MT | 20 | 20 MT | 50 | Bag and liner, or none if meltable |
| Steel drum | 185 kg | 80 | 14.8 MT | 68 | 80 steel drums per container |
| Steel drum | 180 kg | 80 | 14.4 MT | 70 | 80 steel drums per container |
| Steel drum | 150 kg | 80 | 12 MT | 84 | 80 steel drums per container |
| 25 kg carton or multi-wall kraft bag | 25 kg | Set by the pallet pattern and stack height, not by a fixed count | Confirm on the loading plan | Confirm on the loading plan | Cartons or kraft sacks, liners and pallets |
| Bitutainer / heated tank container | 20–25 MT | 1 unit | 20–25 MT | 40–50 | None; the binder moves and arrives as a liquid |
| Bulk vessel parcel | Not packed | Not applicable | Set by the parcel | Not containerised | None |
Every packing figure quoted on this site comes from two facts: what fits geometrically inside a 20-foot container, and what that box is legally allowed to weigh. Here is the whole calculation, so any quotation you receive can be checked against it rather than believed.
A general purpose 20-foot container built to ISO 668 has internal dimensions of roughly 5.90 m long, 2.35 m wide and 2.39 m high — about 33 m³ — a tare of 2,200 to 2,300 kg and a maximum gross mass of 30,480 kg stamped on its CSC safety approval plate. That leaves a payload in the region of 28,200 kg. Bitumen is roughly as dense as water, so the container runs out of permitted weight long before it runs out of space, and every packing format is really an answer to the question of how much of those 28.2 tonnes you can actually use. The full container discussion is on the containerised bitumen shipment page.
A one-tonne block at a cold density of about 1.03 t/m³ is roughly 0.97 m³. Slumped into its bag and set on a pallet, the footprint comes out at something like 1.15 to 1.20 m square. Lay that on the container floor: 5.90 ÷ 1.18 gives five along the length, and 2.35 ÷ 1.18 gives two across the width — ten bags per tier. The internal height of 2.39 m against a bag-plus-pallet height a little over a metre gives two tiers and not three. Ten by two is 20 bags, 20 MT net, and that is where the site standard figure comes from.
Notice what the limit is. Twenty tonnes net plus bags, liners and pallets is roughly 20,100 to 20,600 kg of cargo gross, or about 71 to 73 % of the 28,200 kg payload. There is weight left in the box and nothing to put in it, because the constraint is stack height and stack stability rather than mass. A third tier is unavailable twice over: the height is not there once pallets are counted, and the block in the bottom tier softens in transit and will not carry two tiers above it.
A steel drum of 200 to 210 litres nominal, dimensioned to the ISO 15750 series, is about 570 to 585 mm in diameter and 860 to 890 mm tall. Ten fit along the container length and four across the width — forty per tier — and drums are stacked two tiers and no more, for the same softening reason. Ten by four by two is 80 drums, and because the count is geometric it holds at every fill weight:
Add a drum tare of 20 kg, the middle of the usual 18 to 22 kg range, and 20 pallets at around 25 kg each, and the cargo gross becomes about 14,100 kg, 16,500 kg and 16,900 kg respectively — the same basis used on the drums page, and the same basis as the bag figures below, so the two are read like for like. Against a 28,200 kg payload that is 50 %, 59 % and 60 %. A drummed container ships around half empty by weight and pays a full slot to do it. The drum itself is covered on the new steel drums page.
Against 180 kg drums, bags remove 20 containers from a 1,000 MT programme, which is 29 % fewer boxes. Against 150 kg drums the saving is 34 containers, or 40 % fewer. Read the other way, one container of bags carries what 1.39 containers of 180 kg drums carry, or 1.67 containers of 150 kg drums. Each container removed takes with it its ocean freight, its terminal handling at both ends, its documentation, its inland haulage and its unpacking labour — and, at many destinations, its share of demurrage and detention risk.
A thousand tonnes is 1,000 bags. The same thousand tonnes is 5,556 drums at 180 kg, 5,406 at 185 kg, or 6,667 at 150 kg. Every one of those drums is a lift, an opening operation, a decanting cycle and a piece of scrap to move off the site. That line appears on no quotation, and for a buyer paying labour at the discharge point it can outweigh the freight difference — but it is a number only the receiving site can work out, from its own labour rate and its own handling time per unit. It is also the line that reverses when the buyer has no lifting equipment, because then the drum count is an advantage rather than a cost.
A 20 kg drum tare against 180 kg of net product is about 111 kg of steel per tonne of binder; against 185 kg it is about 108 kg; against 150 kg it is about 133 kg. A 1,000 MT programme in 180 kg drums therefore lands roughly 111 tonnes of residue-bearing steel at the destination. Bags are a different order of magnitude: cargo gross of 20,100 to 20,600 kg against 20,000 kg net is 100 to 600 kg of packing per container including pallets, or 5 to 30 kg per tonne of binder, and almost none of it is metal. On a meltable bag the film goes into the charge and the pallet is the only thing left standing on the yard.
The two numbers point in opposite commercial directions, which is worth knowing before the decision is made. Where a local market for empty drums exists, resale of the empties offsets part of the packing premium, and whether one exists is a question for the destination rather than something a seller can state on the buyer's behalf. Stripped bag fabric and liner have no equivalent outlet: bag waste is smaller and cheaper to move, but it is a disposal cost rather than a recovery.
Bulk is not a packing at all; it is a transport method, and the comparison changes shape. A bitutainer or heated tank container carries 20 to 25 MT in one container slot, so a 1,000 MT programme is 40 to 50 containers — equal to bags at the bottom of the range and better than bags at the top. A bitutainer loaded to the top of its range plus its own insulated tare approaches the plated 30,480 kg, which is why capacity is quoted as 20 to 25 MT rather than higher: on that format the CSC plate, not the product, sets the fill.
The saving is not only in container count. Bags save freight. Bulk saves freight and the entire packing cost and a heating cycle, because the binder never solidifies and never has to be brought back. Every re-melt ages the binder slightly and moves penetration toward the hard end of its band, so packed material carries a small technical cost as well as a commercial one. If the destination can receive and hold hot binder, the right comparison is not on this page at all — see bulk bitumen supply.
Bulk does carry one obligation that packed cargo does not, and it belongs in the comparison. Solid bitumen at ambient temperature is unregulated for transport, which is why bags and drums move as ordinary cargo. Binder carried at or above 100 °C is UN 3257, elevated temperature liquid, n.o.s., a Class 9 dangerous good under the IMDG Code, with the declaration, marking, placarding and carrier acceptance that follow from that classification. It is a documentation burden rather than an obstacle — heated tank containers move on it routinely — but it is the reason a bitutainer comparison has to be priced rather than assumed from the container count alone.
Select the jumbo bag option to convert an order quantity into bags and 20-foot containers, or switch packing to compare directly against drums.
Bags are not a drop-in replacement for drums. Six things have to be settled before the container arrives.
Bags cannot be decanted, chipped or poured like drums. The unit is charged whole or as a stripped block and melted down. Without a melter the cargo cannot be put to use.
A one-tonne unit needs a forklift with adequate capacity, or a crane with a suitable hook and slings. Bags have lifting loops for this; a drum handler will not move them.
Bags are less robust than steel. Store under cover, off the ground, clear of standing water, out of direct sun in hot climates, and stacked no more than two units high — the same limit that applies inside the container, and for the same reason.
Softer grades deform more readily in transit heat. If bags are fixed, the grade choice has to account for that; if the grade is fixed, the packing choice does.
Twenty one-tonne units come off faster than eighty drums, but each lift is heavier. Confirm your unloading bay and equipment can take the unit weight.
For lined bags, someone strips and disposes of the bag and liner. For meltable bags there is nothing to dispose of, which is often the whole reason for choosing them.
A price advantage that arrives as cargo the buyer cannot lift, cannot charge into a melter and has nowhere to put is not an advantage. These are the capabilities that must exist before the container is booked, each with the specific figure that decides it. Every row is a hard stop rather than a preference: where one of them is missing the cargo stops moving, and no adjustment to the purchase price restarts it.
| Capability | The figure that decides it | What goes wrong without it | What to confirm before ordering |
|---|---|---|---|
| Lifting equipment rated for the unit | A counterbalance forklift's plated capacity is stated at a nominal load centre, commonly 500 mm. A block roughly 1.15 m square has its centre of mass further out than that, so usable capacity is below the headline figure | The container is emptied onto the ground and the cargo then cannot be moved again | The truck's capacity plate, the load centre it is rated at, and whether a crane with slings is available as an alternative |
| A lifting attachment that suits loops | Loops are designed to be lifted vertically. Spreading them outward raises the tension in each loop above the quarter of the load it would otherwise carry | Loops tear and a one-tonne block ends up on the ground with nothing to pick it up by | Whether a lifting bar, hook frame or fork-mounted jib is on site, not just a pair of forks |
| A melter that physically accepts the unit | The charging aperture in millimetres, not the rated tonnes per hour. A block roughly 1.15 m square will not enter a unit built to take a 0.585 m drum | The block has to be broken up before it can be charged, which is manual hot work on a one-tonne unit | The internal charging dimensions from the melter's own data plate or manual, checked against the bag footprint in the offer |
| A melter whose heat source suits the film | A meltable film has to reach its melting range and then be dispersed through the charge | On a static unit with no circulation or agitation, film can survive as unmelted residue on the surface of the binder | Whether the melter agitates or circulates, and whether the producer has run that film in that type of unit |
| Melting rate against consumption rate | Melter throughput in tonnes per hour against the plant's peak binder draw in tonnes per hour | The plant waits on the melter, which is the same delay the packing decision was meant to avoid | The manufacturer's rated throughput for the melter and the plant's own peak demand |
| Somewhere to put the material | Covered hard standing, off the ground, out of direct sun, stacked no more than two units high | Blocks slump and weld together, loops degrade under ultraviolet light, and mineral dust from a soil yard goes into the melter with the binder | The covered area available in square metres, divided by the footprint per bag, against the tonnage on order |
| A route for the packaging waste | One woven outer and one liner per tonne on a lined bag; nothing on a meltable bag except the pallet | Stripped fabric accumulates on the yard, and unlike steel it has no scrap outlet to offset the cost | Who strips the bags, where the material goes, and whether that is priced into the discharge operation |
| A way of establishing weight | Net weight per bag is established by weighing. A cast block contracts by 7 to 8 % in volume as it cools, so a correctly filled bag looks slack | Short-weight arguments cannot be run after discharge because nobody has a number to argue from | Whether a weighbridge or platform scale is reachable, and that per-bag weight tolerance is agreed in the contract |
| Hot-work safety at melt-out | A one-tonne charge releases a far larger mass of hot binder at once than a 180 kg drum does | Burns happen at melt-out and transfer rather than in the container, and the volume released in a single charging operation is not what drum handling prepares a crew for | That the crew is briefed: cool any contact with clean cold running water for at least 20 minutes, never peel or solvent-strip adhered bitumen, and get the casualty to medical care with the bitumen still in place |
This is the failure mode that catches buyers out, and it is entirely predictable from the grade and the route.
A steel container standing on a terminal apron or on deck in tropical latitudes gets substantially hotter inside than the outside air. Ambient air at 35 °C and direct sun on a dark steel box produce internal temperatures well above that. Now put that against the softening point of the cargo:
The distinction matters here more than it does on a specification page. If the packing decision rests on the softening point and the standard does not set one, the number the cargo will actually arrive with is whatever the batch certificate reports, and it has to be seen before the packing is fixed rather than assumed from the grade name. Softening point is not a melting point — bitumen softens progressively rather than melting at a threshold — but a soft grade held near that range for days will slump, and bags will deform, press against one another and can fuse into a single mass that has to be broken apart at destination. Steel drums have the same problem but their walls hold the shape.
Oxidized grades are the opposite case. Across the blown range this site publishes softening points of 70 to 155 °C by ASTM D36 — grades such as 85/25 and 115/15 are named for the softening point itself — so blown grades in bags are largely untroubled by container heat — which is why bagged and carton packing is standard for roofing and industrial material and why the same buyer may sensibly take blown grades in bags and paving grades in drums.
Bags are not universally better. These are the situations where drums or bulk are the correct answer, and it is very much cheaper to know now than at discharge.
The fourth point deserves emphasis because it is often missed. Every time a paving binder is melted down it ages a little: penetration drops and the binder moves toward the hard end of its band. A buyer who takes packed material and re-melts it is paying for that twice — once in the packing cost and once in binder quality. Where the receiving infrastructure allows bulk, bulk is technically as well as commercially better.
Transit heat is a matter of days or weeks. Yard storage is a matter of months, and it attacks the packaging rather than the binder. Polypropylene degrades under ultraviolet light, so a bag that has stood uncovered through a hot summer can hold its contents perfectly well and still have lifting loops that will not take a one-tonne lift. There is no inspection that establishes this from a distance, and once the loops are suspect the only safe route is to cut the bag away and handle the block — which is precisely the operation the buyer chose bags to avoid.
Then there is the block itself. At ambient temperatures approaching the softening point, a stacked unit slumps under the one above it, adjacent units press together and weld, and a two-high stack becomes a single mass that has to be broken up before any of it can be charged. Nothing is chemically wrong with the binder when this happens and the Certificate of Analysis still holds; the cargo has simply stopped being twenty separately liftable units.
The general shelf-life position is set out on the shelf life and storage page, and for bagged material it reduces to one sentence: bag integrity governs throughout. Sealed drums under cover are limited by rust, which is slow and visible. Bags are limited by fabric condition, which is faster in sunlight and much harder to judge. If material is going to be held for months in a hot yard before it is used, drums are the packing that survives the wait.
This is worth separating from the melter point because buyers assume it is solvable on the day. It is not. A 180 kg drum can be rolled on its chime by two people, tipped off a tailgate onto a tyre and moved across a yard with no machine at all. A one-tonne block cannot be moved by any number of people. There is no partial answer and no improvisation: either a forklift or crane rated for the unit is present at every point the cargo has to move — out of the container, across the yard, into the melter — or the cargo is stationary.
Hiring a machine for the discharge day solves the discharge and leaves the identical problem standing three weeks later when the material is wanted. Count the lifting points rather than the lifts, and count them before the packing decision rather than after the booking. Where the answer is anything less than complete, the drum count that looked like a labour penalty in the arithmetic above becomes the reason the cargo is usable at all.
Packing has to survive the worst-handled part of the journey, and for a good many destinations that is not the ocean leg. A woven bag abrades. Dragged across a truck bed, caught on a tailgate, set down on broken concrete, or handled with unpadded forks, the fabric tears — and a torn bag around a one-tonne block cannot be repaired in the field. Solid bitumen does not spill, so the consequence is not a mess; it is a unit that can no longer be lifted, on a truck, a long way from the machine that could deal with it.
Steel drums tolerate being handled badly by people who have never handled bitumen before, and where the inland leg runs on flatbeds, over unmade roads, or through transfers at small depots, that tolerance is worth more than the freight saving. The same reasoning applies wherever cargo changes hands more than once before it reaches the melter: each transfer is an opportunity for a bag to be handled by someone who has no reason to know that the fabric is the only thing holding the load.
The softening points above are the reason, and the softer end of the range makes the point sharply. For the soft European grades these are specification limits and not typical values: EN 12591 requires a ring and ball softening point of 39 to 47 °C for grade 100/150 and 35 to 43 °C for grade 160/220, measured to EN 1427. A binder sitting at the bottom of either window is fully in grade. Those are temperatures a closed container reaches in ordinary summer weather, never mind in the tropics, and they are temperatures an open yard reaches in a good many import markets.
A bag has no structure of its own. The block is the structure, and once its core passes the softening range the block takes the shape of whatever it is resting against, the fabric follows it, and the lifting loops finish up buried or bearing on material that no longer supports them. Drums fail differently and less expensively: the steel holds the shape whatever the contents do, and the failure shows up at the closures and in the stack rather than in the ability to move the unit at all. Below roughly a 60/70 the case for bags weakens with every step down the penetration scale, and on the softest paving grades it is not a close decision.
The corollary is the useful part. Where the destination specification permits it, choosing the harder of two acceptable grades is a genuine risk control on a bagged shipment, and it costs nothing. Where the grade is fixed by the project and it is a soft one, the packing decision has already been made for you.
Read down the left column to the row that describes the site the cargo is actually going to, rather than the one that describes the buyer's ambition for it. The third column gives the verdict on bags specifically, and the fourth gives the single fact that decides the row.
| Destination type | Packing that fits | Bags: yes or no | The deciding factor |
|---|---|---|---|
| Asphalt plant with a block melter and lifting rated for one tonne, short haul from the port | Jumbo or meltable bags | Yes — this is the case bags exist for | 20 MT per container against 14.4 MT in 180 kg drums, and no steel to strip, store or scrap |
| Asphalt plant with heated binder storage and no jetty access | Bitutainer or heated tank container | No — bags are a step backwards here | 20 to 25 MT in the same container slot, no packing cost at all, and no second heating cycle |
| Terminal with heated shore tanks and a berth | Bulk vessel parcel | No | Lowest cost per tonne by a wide margin, with quantity established by independent survey rather than by unit count |
| Contractor buying for one project, hired equipment, no melting plant | New steel drums, 180 or 185 kg | No | A drum can be moved and heated with equipment that can be hired for a single job; a one-tonne block cannot be moved at all without a rated machine |
| Trader breaking bulk and reselling to small contractors | New steel drums, 150 kg where road weight limits bite | No | Drums sell in ones and twos. A one-tonne unit cannot be divided at any point before the melter |
| Roofing, waterproofing or pipe-coating plant working on oxidized grades | 25 kg cartons or kraft bags, or one-tonne bags where lifting exists | Yes for the one-tonne format | Oxidized softening points run from about 70 °C to 155 °C by ASTM D36, far above any container or yard temperature the block will meet |
| Remote inland site reached by a long unmade road with transfers on the way | New steel drums | No | The packing has to survive the worst-handled leg. Woven fabric abrades, and a torn bag around a one-tonne block cannot be lifted or repaired in the field |
| Yard in a hot climate holding stock for months before it is drawn down | New steel drums under cover | No | Ultraviolet light degrades the fabric and the loops, and stacked blocks slump and weld together as ambient approaches the softening point |
| Project specification that prohibits additives of any kind | Drums, or lined jumbo bags with the liner stripped | Lined only, never meltable | The meltable film enters the binder. Where it is not permitted, the cost advantage is irrelevant |
| Destination enforcing strict axle loads or a low gross weight limit | Any packing, loaded to the road limit rather than to the container plate | Yes, with the load plan set to the road limit | A bagged 20-foot container declares a verified gross mass of roughly 22,350 to 22,850 kg; the tractor and chassis under it have to be legal at that weight |
Seven lines in the enquiry that prevent the common disputes on bagged cargo. The first four settle the commercial terms; the last three settle whether the bag that arrives is the bag that was priced.
State which. If meltable, ask what the film is, at what proportion it enters the charge, and whether it affects the solubility line on your specification.
Confirm the invoiced weight is net of packing, and agree a per-bag weight tolerance so a routine filling variance is not treated as short delivery.
State whether bags are palletised, how they are restrained inside the container, and whether a release film or interleaving is included.
Agree that bag condition is recorded at loading and on discharge. Deformation claims that were not documented at load port are very hard to run.
Name ISO 21898 for flexible intermediate bulk containers for non-dangerous goods, ask for the safe working load and the safety-factor ratio of the design type, and ask whether the fabric is UV-stabilised. If the cargo will stand in a yard rather than going straight into a melter, the ultraviolet answer is the one that decides whether the unit is still liftable when it is finally wanted.
Ask at what temperature the binder is cast and how long bags stand before they are stuffed. A one-tonne block sheds heat slowly, and a bag stuffed before its core has set will deform under the tier above it however well the container is restrained.
Grade, batch number, net weight and production date on each bag, so a unit can still be matched to its Certificate of Analysis after a season in a yard. Fabric marking weathers faster than drum stencilling, which is why this belongs in the order rather than being assumed.
Around 20 MT, as twenty one-tonne bags. That compares with about 12 MT as 80 drums of 150 kg and 14.4 MT as 80 drums of 180 kg. Final counts depend on pallet configuration and any destination gross-weight restriction.
A lined jumbo bag is cut open at destination and the bag and liner are stripped away and disposed of. A meltable bag is charged into the melter whole and its film becomes part of the binder. Name which one you want in the enquiry, because both are commonly quoted simply as bags.
Because the outer bag cannot take the heat of the fill. Binder is cast at roughly 140 to 160 °C and woven polypropylene melts at about 160 to 165 °C, softening well below that, so the fabric cannot be the surface the hot bitumen touches. The liner takes that heat, then gives the set block a surface it can be separated from, and keeps dust and moisture off the block in storage. It also explains why the liner cannot simply be melted along with the contents: a material chosen to survive a 150 °C pour will survive a melter too. A film that disappears into the charge has to melt below melter temperature, which is the opposite requirement, and that is why the meltable bag is a different product rather than a cheaper version of the same one.
It enters the binder, so it is a fair question to put to the producer: what the film is, at what proportion, and whether it affects any line your project tests. Solubility in trichloroethylene to ASTM D2042 is the one to check specifically, since polyolefin films are not necessarily soluble in that solvent and a 99.0 % minimum is a hard limit in ASTM D946 and ASTM D312, with EN 12591 setting the same minimum by EN 12592. Ask for the film mass per bag in kilograms and divide it by the 1,000 kg net to get the dosage as a mass fraction of the charge, then put that figure to whoever approved the binder.
Usually on landed cost, and not primarily because the packing is cheaper. Twenty MT per container against 14.4 MT means 20 fewer containers on a 1,000 MT order, and freight, terminal handling and destination charges all scale with container count. There is also no steel to dispose of.
A forklift with adequate capacity or a crane with suitable slings for the lifting loops, and a melting unit. Bags cannot be decanted the way drums can, so without a melter the cargo cannot be put into use.
Four checks, in this order. Read the capacity plate on your forklift and note the load centre it is rated at, commonly 500 mm, against a block roughly 1.15 m square whose centre of mass sits further out than that. Confirm you have a lifting bar or hook frame so the loops can be lifted vertically rather than spread outward, which raises the tension in each loop. Measure the charging aperture of your melter in millimetres, because the aperture rather than the rated throughput is what disqualifies most units built to take 585 mm drums. Then identify the covered hard standing where the bags will sit, at the bag footprint, stacked no more than two high. If any of the four fails, drums are the correct packing whatever the landed cost comparison says.
They can, on soft grades through hot routes. Container interiors exceed ambient air temperature substantially in the tropics, and a grade with a softening point in the mid-forties held near that range for days will slump. Match packing to grade and route, ask for a release film or interleaving, and record bag condition at both ends.
Yes, and it is the normal packing for it. Blown grades run from about 70 °C to 155 °C on softening point by ASTM D36, so container heat is not the concern it is for paving grades. Roofing and industrial material is routinely shipped in 25 kg kraft bags and cartons as well as one-tonne bags.
No. If you can receive and hold hot bitumen, bulk or bitutainer supply beats both bags and drums — no packing cost, no waste, and no second heating cycle. Every re-melt ages the binder slightly and drops penetration, so packed material carries a small quality cost as well as a commercial one. A bitutainer also carries 20 to 25 MT in the same container slot that takes 20 MT of bags.
Send the grade, tonnage, destination port and Incoterm, and say whether you need lined or meltable bags. If you are undecided between bags and drums, say so and both will be priced so you can compare landed cost rather than product price. Telling us what melting unit and what lifting equipment are on site lets the packing recommendation come back with the quotation instead of after it.