Bulk means the bitumen never enters a package. It is loaded hot into a heated tank, moves as a liquid, and is discharged as a liquid into the buyer's tank.
Every other way of buying bitumen puts a container between the filling point and the paving plant: a 150 kg or 180 kg steel drum, a one-tonne jumbo bag, a meltable poly bag. Bulk removes it. The binder is loaded at a typical 150 to 170 °C, travels in an insulated and heated tank, and arrives above the temperature at which it can still be pumped. Nothing is packed at origin and nothing is unpacked, decanted or thrown away at destination.
That single difference reshapes the whole transaction. Quantity stops being a drum count and becomes a survey figure derived from a gauge, a temperature and a density. Quality control moves from sampling drums at the container door to sampling a shore tank before the transfer starts. The buyer stops needing labour, a drum decanter and a waste route, and starts needing tankage, heating coils and pumps. The cost structure loses two whole line items — the package itself, and the energy and time spent melting what is inside it.
Heated tank vessel. The format for large parcels. Cargo travels in dedicated compartments fitted with heating coils, and the vessel maintains temperature on passage. Indicative parcel sizes run from around 1,000 MT for a small coastal lot up to 10,000 MT and beyond on a larger ship, often split across compartments so that more than one grade or more than one receiver can be served on the same voyage. This is terminal-to-terminal trade: it needs a berth that will accept a hot oil cargo, a shore line, and tank capacity standing empty and hot on the day the ship arrives.
Bitutainer or heated tank container. The mid-size format, and the one that has done most to open bulk supply to buyers who could never handle a vessel parcel. A bitutainer is a bitumen tank built into or onto a 20-foot ISO frame, insulated, and fitted with a heating system — commonly a diesel-fired burner, electric elements, or a connection for an external thermal oil or steam source. Indicative capacity is 20 to 25 MT. Because it sits in a standard container slot it moves on ordinary container equipment: normal liner bookings, normal cranes, normal chassis, normal inland trucking. Discharge is through a bottom valve, by gravity or by an on-board pump.
Road tanker. The regional format. An insulated tanker collects from a terminal or filling plant and delivers direct to an asphalt plant, indicatively 20 to 30 MT per load depending on the vehicle and the axle-weight rules of the country. It discharges through the tanker's own pump into the plant's storage tank. The economics work within about a day's driving of the loading point; beyond that the heat loss and the vehicle time start to defeat the saving.
Bulk is not a grade. Bitumen 60/70, VG-30, PG 64-22 and an oxidized grade can each be supplied in bulk or in drums; the grade is decided by the specification, the format by what the receiving end can handle. Bulk is also not simply a large order — 400 tonnes in drums is a large order in packed form, not a bulk supply, and it carries every packing cost that bulk avoids.
One thing bulk is definitely not is a flexitank job. Flexitanks are single-use bladders for ambient, non-hazardous liquids. Nothing at 150 °C goes into one. Any offer that proposes moving hot bitumen in a flexible bladder or an unheated tank is describing something that will arrive as a solid block.
Parcel size, temperature and discharge arrangement differ across the three, and so does the list of things the buyer must already own before the cargo can be accepted.
| Format | Indicative parcel size | Typical loading temperature | Discharge arrangement | What the buyer must already have |
|---|---|---|---|---|
| Heated tank vessel | About 1,000–10,000+ MT per parcel, often split across compartments | 150–170 °C | Ship's cargo pumps to a shore line; coils maintain temperature on passage | Berth or terminal access for a hot oil cargo, shore tankage in thousands of tonnes, calibrated tank capacity tables |
| Bitutainer / heated tank container | 20–25 MT per unit; multiples for larger lots | 150–170 °C | Bottom valve by gravity or on-board pump; reheating before discharge if the unit has cooled in transit | Level hard standing, a discharge connection and hose, receiving tank of at least one unit plus ullage |
| Road tanker | 20–30 MT per load, set by vehicle and axle-weight limits | 140–170 °C | Tanker-mounted pump through a traced hose into the plant tank | All-weather access for a heavy vehicle, a coupling that matches, free ullage in the receiving tank |
Bulk supply is only cheaper if the receiving end works on the day. Four capabilities decide it: heated tankage, working heat transfer, pumps rated for the viscosity, and honest temperature measurement.
The receiving tank must hold the full parcel plus free ullage for thermal expansion, and it must be able to keep product in a working range of roughly 140 to 165 °C. Insulation matters as much as the heat source: an uninsulated tank is a radiator, and the fuel burnt holding it hot is a real operating cost that belongs in any honest bulk-versus-drums comparison. A part-filled tank cools faster than a full one because the surface-to-volume ratio is worse, which is why receiving a small parcel into a large tank is less efficient than it looks.
Heat reaches the bitumen through coils carrying saturated steam or thermal oil, or through an external heat exchanger. Two rules govern them and both are absolute. First, coils must stay covered by product at all times. A coil exposed above the liquid level heats a thin film against hot metal, which cokes, carbonises and contaminates the tank — and the carbon it leaves behind will keep appearing in your product long after the incident. Second, the heating medium temperature has to be limited. Saturated steam at about 10 barg sits near 184 °C, which is a sensible working ceiling; thermal oil systems can go much higher and must be limited deliberately, because it is the film temperature at the tube wall, not the bulk tank temperature, that degrades the binder. Never fire a heater on a dry or partially covered coil.
Bitumen at 150 °C is a genuinely viscous liquid and it stiffens quickly as it cools. Transfer is normally done with positive displacement pumps — gear or screw types — that are jacketed or traced so they do not set solid between transfers, and every line, valve and hose in the path must be steam-traced or electrically traced and insulated. A single untraced metre of pipe is where a transfer stops. The pumpability question has a published number attached to it: AASHTO M320 and ASTM D6373 cap the rotational viscosity of the original binder at 3.0 Pa·s at 135 °C, measured to ASTM D4402, precisely so that the binder can be pumped and handled at a plant. M320 allows that requirement to be set aside where the supplier can demonstrate the binder is adequately pumped and mixed at higher temperatures, so read it as a handling assurance rather than an absolute bar. A binder that meets it and arrives inside its working temperature range will move through correctly specified pumps.
One warning about units, because binder data sheets mix three systems on the same page. Rotational viscosity is a dynamic viscosity and is quoted in Pa·s or in poise: 3.0 Pa·s is 30 poise, since 1 Pa·s = 10 poise. The figures quoted at 135 °C in cSt are a different quantity, kinematic viscosity, where 1 cSt = 1 mm²/s exactly; the two are linked only through density, so a poise figure and a cSt figure cannot be compared side by side. Nor can any two viscosity figures quoted at different temperatures. Read the unit and the test temperature before you read the number.
Temperature is not a comfort reading on a bulk cargo — it is an input to the quantity calculation and to the acceptance decision. A fixed thermowell and gauge on the tank is the minimum; a calibrated portable probe used at more than one depth is what a surveyor will expect, following the principles of API MPMS Chapter 7. Quantity corrected on a temperature nobody verified is quantity nobody can defend.
The last capability is organisational rather than mechanical: the tank must be empty, hot, gauged and ready at the moment the cargo presents. Bulk does not wait politely. A vessel on demurrage, a tank container accruing detention or a tanker driver on hours is a cost that lands on somebody, and the contract decides who. Nominate the receiving window realistically and set a minimum discharge temperature in writing rather than discovering it on the quay.
A bulk enquiry is answerable in one exchange if the buyer can confirm these lines. Each one carries either a value or the published method that produces it.
| Requirement | Typical value or setting | Standard or method | What it prevents |
|---|---|---|---|
| Storage temperature, working | 140–165 °C | Plant practice; confirm against supplier SDS | Product too stiff to transfer at one end, needless ageing at the other |
| Storage temperature, held over days | below 150 °C | Plant practice | Oxidative hardening and penetration loss while the tank waits |
| Maximum heating temperature | do not exceed 180–190 °C | Flash point by ASTM D92: min 250 °C on a typical export specification, min 232 °C under ASTM D946 | Fuming, rapid oxidation and an approach to the flash point |
| Heating medium temperature | Saturated steam at about 10 barg is near 184 °C | Steam tables; thermal oil system limits | Film temperatures at the tube wall that carbonise binder |
| Coil coverage | Coils covered by product at all times | Operating rule | Coking on an exposed coil and permanent tank contamination |
| Transfer pump type | Positive displacement, jacketed or traced | Pump maker's viscosity rating | Cavitation and loss of prime as the binder stiffens |
| Pumpable viscosity ceiling (dynamic) | 3.0 Pa·s maximum at 135 °C, equal to 30 poise | ASTM D4402 / AASHTO M320 / ASTM D6373 | Accepting a binder the receiving pumps cannot actually move |
| Kinematic viscosity at 135 °C | min 250 cSt (VG-10) rising to min 400 cSt (VG-40); 1 cSt = 1 mm²/s | ASTM D2170 / IS 73:2013 | Comparing binders quoted on different temperature bases |
| Absolute viscosity at 60 °C (dynamic) | IS 73:2013 sets a minimum only — 2,400 poise for VG-30, equal to 240 Pa·s; ASTM D3381 instead brackets AC-30 at 3,000 ± 600 poise | ASTM D2171 / IS 73:2013 / ASTM D3381 | Assuming a grade name tells you the handling behaviour, or that two grading systems mean the same thing |
| Lines, valves and hoses | Steam or electrically traced and insulated end to end | Operating rule | A set line that has to be cut out and replaced |
| Temperature measurement | Fixed thermowell plus a calibrated portable probe, read at depth | API MPMS Chapter 7 | Quantity corrected on a temperature nobody verified |
| Tank gauging | Current calibrated capacity table for that specific tank | API MPMS Chapter 3 | Volume figures that cannot be defended in a claim |
| Water content of received product | 0.2 vol % maximum on a typical export specification | ASTM D95 | Foaming on heating and a steam release inside the tank |
| Free ullage before discharge | Room for the full parcel plus thermal expansion | Tank capacity table | Overfill during a hot transfer |
| Vapour space gas testing | Test before any tank-top work; H₂S TLV 1 ppm TWA, 5 ppm STEL; IDLH 100 ppm | ACGIH TLV / NIOSH IDLH | Hydrogen sulphide exposure at an open hatch |
| Sampling arrangement | Valve or dip samples spread across the transfer, sealed | ASTM D140 | A certificate that cannot be tied back to the cargo |
Where a buyer can genuinely receive it, bulk is both cheaper and technically better than packed material. Both halves of that sentence deserve the arithmetic behind them.
A drum is bought new for every tonne shipped and is never bought back. At 150 kg net per drum that is 6.67 new steel drums for every tonne of binder; at 180 kg it is 5.56. The steel is a manufactured item with its own commodity price, it is filled and capped by hand, it adds roughly 18 to 22 kg of tare per drum to the weight that gets freighted, and it occupies volume in the container that product could have occupied. Bulk removes that line entirely. It is the single largest and most predictable saving in the comparison.
The 6.67 drums per tonne do not evaporate at destination. They arrive at the plant, they hold residue, and somebody has to cut, drain, stack, store and dispose of or sell them, often under a waste permit. Jumbo and meltable bags reduce the problem but do not remove it. Bulk removes it, and it removes the labour of decanting with it. For buyers in markets where scrap handling is regulated, this is not a marginal item.
By the time drummed binder reaches a buyer it has already been heated once and allowed to go solid — hot into the drum at the filling point, cold by the time the container doors open. Putting it to use means driving the whole mass through a second heat to melt it back out. A bulk parcel skips that step for the simple reason that it never solidified: it goes from ship or tanker straight into a hot tank. One cycle, not two.
That matters because every heating cycle ages the binder. The specifications concede the point by measuring it. The thin film oven test, ASTM D1754, heats a 3.2 mm film at 163 °C for 5 hours; a typical Middle East export specification for a 60/70 paving grade then allows a maximum mass loss of 0.2 % and a maximum drop in penetration of 20 % of the original value, while ASTM D946 writes the same idea the other way round, as a minimum retained penetration. The rolling thin film oven test, ASTM D2872, is used the same way, and IS 73:2013 caps the viscosity ratio at 60 °C after RTFOT at 4.0. Those limits exist because controlled heating measurably hardens bitumen — penetration falls, softening point rises, ductility drops. A drum melted with a burner played against the drum wall is a far harsher thermal event than either standard test, applied unevenly, without instrumentation, by whoever is on shift. The binder that comes out of that process is not the binder on the Certificate of Analysis.
The payload comparison is stark in the same container slot. A 20-foot container of 150 kg drums carries about 12 MT of product; at 180 kg drums about 14.4 MT; a bitutainer in the same slot carries 20 to 25 MT. You are paying broadly the same slot cost to move nearly twice the binder. On a vessel parcel the comparison stops being close at all.
Bulk is not free, and any supplier who presents it as pure saving is not describing the trade. It moves cost from the package to your tank farm: fuel to hold a tank hot, maintenance on coils and traced lines, a bigger single working-capital commitment per parcel, and exposure to demurrage or detention if the receiving end is not ready on the nominated day. It also concentrates risk — one tank of off-specification product is one problem affecting the whole parcel, where a drummed lot can be quarantined drum by drum. The right comparison is never price per tonne. It is landed cost per tonne into your storage tank, with packing, freight, discharge, decanting labour, waste disposal and reheating fuel all in the same column.
Bulk is the default recommendation for buyers who can receive it, and the wrong recommendation for everyone else. These are the situations where packed material is the better technical answer, not merely the fallback.
If the receiving point cannot hold product above roughly 140 °C, bulk stops at the gate. Drums or meltable bags with a proper decanter are the correct answer, not a bulk parcel with a plan to sort the tank out later.
Below a single tanker or tank-container load, bulk becomes awkward. Part-filled heated tanks cool faster and age product, and a slow-moving hot tank quietly hardens the binder you paid for.
Every hour after the tanker leaves the terminal costs temperature. Where the site is days inland with a transhipment in the middle, packed material travels far better than heat does.
Holding a tank hot for months burns fuel and ages the binder continuously. Sealed drums stored under cover age very slowly at ambient. Long storage favours packing, and that is a technical judgement rather than a cost one.
One parcel serving many sites means decanting somewhere anyway. The packing you avoided at origin reappears as handling, and usually at a worse price than the original drum.
A vessel parcel needs a berth that will accept a hot oil cargo, a shore line in condition, and tankage free on the day. If any of the three is uncertain, the cargo waits and somebody pays for the waiting.
This is where bulk bites. Bitumen is bought and invoiced by weight, but in a tank it is measured as a volume, and the two only agree at one temperature.
Bitumen expands on heating like any liquid hydrocarbon, at a volumetric expansion coefficient of approximately 0.00061 per °C. Work it through on a paving binder of 1.03 t/m³, measured to ASTM D70. Check the temperature basis of your own density figure before you use it: a typical 60/70 export specification quotes a specific gravity band of 1.01 to 1.06 at 25 °C, so a 15 °C figure and a 25 °C figure are not interchangeable inputs. Heating that binder to a 150 °C loading temperature multiplies its volume by about 1.082 and drops its density to roughly 0.952 t/m³. In the form a contract needs it: a tonne fills about 0.971 m³ cold at 15 °C and about 1.051 m³ hot at 150 °C, an 8.2 % spread on identical mass. Substitute the density from your own Certificate of Analysis wherever you have one — the correction is never better than the density fed into it.
On a drummed cargo that arithmetic is a footnote, because drums are counted and a count does not change with temperature. On a bulk parcel it is the entire quantity argument. Put 3,000 tonnes through the same numbers and the cargo measures about 2,913 m³ cold against about 3,153 m³ at loading temperature: a 240 m³ difference that is heat, not bitumen. The effect runs backwards on arrival. Load at 165 °C, gauge at 135 °C after the voyage, and the tank reads roughly 1.7 % less volume with not one kilogram gone. Nearly every bulk quantity dispute has the same shape underneath it — the seller worked in mass, the buyer worked in volume, the two readings were taken at temperatures thirty degrees apart, and the contract said nothing about which one settled the invoice.
Mass does not change with temperature; volume does. So the contract must fix quantity on a weight basis, and it must spell out metric tonnes rather than leaving the word “ton” to carry three different masses. The metric tonne is 1,000 kg. The long ton is 1.01605 MT. The short ton is 0.90718 MT, which makes it 9.3 % lighter than a metric tonne — or, read the way an invoice reads it, a metric tonne is 10.2 % heavier than a short ton. That gap is wider than most trading margins on the cargo. If operational reality forces a volume figure into the contract, the clause must also name the reference temperature and the correction practice. Do not leave the reference temperature implied either: international bitumen trade normally bases on 15 °C, while US practice bases on 60 °F (15.56 °C), and the two are not the same number.
Weight basis without a point of determination is only half a clause. The realistic options, each measuring something different:
ASTM D4311 is the recognised practice for correcting asphalt volume to a base temperature and tabulates coefficients by density group; API MPMS calculation chapters cover the arithmetic on a marine parcel. A survey run strictly to a named practice may differ marginally from a generic coefficient, which is exactly why the practice should be named in the contract instead of assumed.
Bitumen is viscous and it clings. On a vessel parcel, on-board quantity before loading (OBQ) and remaining on board after discharge (ROB) are measured and recorded, and for a cargo of this viscosity the ROB figure is never zero. Agree in advance how ROB is treated, and whether a heating and stripping regime is specified before the ROB gauge is taken. The same principle applies at the small end: a bitutainer that has cooled will not fully drain, and the residue belongs to somebody.
Bulk parcels normally carry a quantity tolerance expressed as a percentage more or less at the seller's or owner's option. Without one, a routine measurement variance is a contractual breach rather than a rounding difference. And the unit and basis must be word-for-word identical across the sales contract, the letter of credit, the survey certificate, the commercial invoice and the bill of lading. A discrepancy between MT on the invoice and cubic metres on the survey report is a standard reason for a bank to refuse documents — and by the time anyone notices, the cargo is on the water.
Knowing the sequence tells you where to be present, which document each stage produces, and which stage to insist on when a supplier proposes to skip one.
The surveyor confirms the identity of the nominated shore tank, checks the capacity table is current, and inspects the receiving compartments or unit for cleanliness and, above all, dryness. Water in a receiving tank is the worst single contaminant in a hot transfer.
Ullage or dip readings are taken on the shore tank and temperature is measured at more than one depth following API MPMS Chapter 7 principles, so that observed volume can be read from the calibrated table against a temperature that was actually verified.
Samples are drawn to ASTM D140, spread across the transfer rather than taken from one convenient point, then composited, sealed with numbered seals and split so each party holds a set for the claim period.
Typically penetration (ASTM D5), softening point (ASTM D36), flash point (ASTM D92), solubility (ASTM D2042), density (ASTM D70), water (ASTM D95) and viscosity (ASTM D2170 or ASTM D4402), with ageing residue tests where the contract requires them. The Certificate of Analysis is issued against the tank or batch, not against the product range.
After the transfer, closing gauge and temperature are taken, observed volume is corrected to the reference temperature using the named practice such as ASTM D4311, density is applied, and mass in air is calculated. This is the figure that reaches the invoice.
Temperature at completion of loading is recorded, the heating regime for the passage is instructed and logged, and the document set is issued. Ask for the sealed retained samples to be receipted, and for the heating log to be continuous rather than two readings taken at each end.
A bulk parcel is accepted on documents, not on a conversation, and its set differs from a containerised drummed shipment in three places: quantity is surveyed rather than counted, temperature has a history, and the tank itself has to be certified fit.
| Document | What it evidences | Normally issued by | What to check before you accept it |
|---|---|---|---|
| Certificate of Analysis | Measured properties of the loaded batch or tank against the contract specification | Loading laboratory or independent laboratory | That it names the tank or batch and the sampling date, and that results scatter rather than sitting exactly on every limit |
| Certificate of quantity | Mass in air, corrected to the reference temperature | Independent surveyor | That it names the reference temperature, the density used and the correction practice applied |
| Opening and closing ullage reports | Observed volume and temperature before and after transfer | Surveyor | Tank identity, the date of the capacity table, and temperatures read at more than one depth |
| Bill of lading or consignment note | Title and the contract of carriage | Carrier, master or road operator | That the quantity, unit and description match the invoice and the letter of credit exactly |
| Sampling and sealed sample certificate | Chain of custody from cargo to laboratory | Surveyor | Numbered seals, the sampling points used, and confirmation that each party holds a set |
| Safety Data Sheet | Hazard data, handling limits and emergency response | Supplier | That it covers the grade actually shipped and addresses carriage above 100 °C |
| Certificate of origin | Origin of the goods for customs and duty treatment | Chamber of commerce | That the goods description matches the invoice and the HS code used, 2713.20 for petroleum bitumen |
| Commercial invoice | The amount payable and the quantity basis it rests on | Seller | Unit and basis identical to the contract and to the quantity certificate |
| Statement of facts / time sheet | Timings at berth or at the plant for laytime and demurrage | Agent or surveyor | That pumping start and stop times and the reason for every stoppage are recorded |
| Heating and temperature log | The temperature history of the cargo in transit | Vessel or transport operator | Continuity through the voyage or journey, not one reading at each end |
| Tank or compartment cleanliness certificate | That the space was fit and dry before loading | Surveyor | The previous cargo carried and an explicit confirmation that the space was dry |
| Receipt for retained samples | That sealed samples travelled with the cargo | Master or driver | That the seal numbers on the receipt match the sampling certificate |
It means the bitumen is supplied with no package at all. It is loaded hot, typically at 150 to 170 °C, into a heated tank, moves as a liquid and is discharged as a liquid into the buyer's storage. It takes three forms: a heated tank vessel for large parcels, a bitutainer or heated tank container of about 20 to 25 MT for mid-size lots, and a road tanker of about 20 to 30 MT for regional delivery.
Typically 20 to 25 MT, in a unit built to 20-foot ISO container dimensions. For comparison, the same container slot filled with 150 kg steel drums carries about 12 MT and with 180 kg drums about 14.4 MT, so a bitutainer moves close to twice the binder for broadly the same slot cost — provided the receiving end can discharge it hot.
High enough to pump. The working transfer range for a paving grade is broadly 140 to 165 °C and loading is typically 150 to 170 °C. The published handling reference point is AASHTO M320 and ASTM D6373, which cap original binder rotational viscosity at 3.0 Pa·s (30 poise) at 135 °C, measured to ASTM D4402, so that the binder remains pumpable. Set a minimum discharge temperature in the contract instead of assuming one; a tank container that has cooled has to be reheated on the quay, which costs days and adds a heating cycle.
Where the buyer can receive it, yes. Bulk removes the cost of 6.67 new steel drums per tonne at 150 kg net, removes the disposal of those drums at destination, moves more tonnes per container slot or per voyage, and removes the labour and fuel of decanting. What it costs back is tank farm operation, a larger single commitment per parcel and exposure to demurrage if the receiving end is not ready. Compare landed cost per tonne into your tank, not price per tonne.
There are two answers, and that is exactly the problem. Cold at 15 °C a tonne of paving binder takes up about 0.971 m³. Hot at a 150 °C loading temperature the same tonne takes up about 1.051 m³. Both figures assume a density of 1.03 t/m³ and an expansion coefficient near 0.00061 per °C, and both describe identical mass. An 8.2 % spread of that kind is why a bulk contract has to be written on a weight basis in metric tonnes with the point of determination named, rather than settled in cubic metres.
Yes, measurably. Heating ages bitumen: penetration falls, softening point rises and ductility drops. The standards assume it and measure it — the thin film oven test (ASTM D1754) heats a 3.2 mm film for 5 hours at 163 °C, and a typical Middle East export specification for a 60/70 grade then allows no more than 0.2 % mass loss and no more than a 20 % drop in penetration, while IS 73:2013 caps the viscosity ratio at 60 °C after RTFOT (ASTM D2872) at 4.0. A drum melted with a flame against the wall is a harsher and far less controlled version of that same test. Bulk avoids the cycle entirely.
An independent surveyor's quantity certificate, built from an opening and closing gauge on a calibrated tank, temperature verified at depth following API MPMS Chapter 7 principles, a density from the batch sample by ASTM D70, and a volume correction to the reference temperature by a named practice such as ASTM D4311. For a road tanker, a certified weighbridge ticket is cleaner still because it removes temperature from the calculation.
Carried above 100 °C it is normally consigned as UN 3257, elevated temperature liquid n.o.s., Class 9, packing group III, which in ADR carries hazard identification number 99 on the orange plate, and under US 49 CFR requires the HOT marking. As a product it is not readily flammable — a paving grade is typically specified at a flash point of at least 250 °C by ASTM D92, and ASTM D946 requires at least 232 °C, either of which puts it in Class IIIB under NFPA 30. The regulated hazard is the temperature, not the flammability. Confirm the exact classification and marking for your route with the carrier before booking.
Send the grade, the tonnage, the bulk format you can receive — vessel parcel, bitutainer or road tanker — the destination and the Incoterm. If you can also confirm your storage temperature, tank capacity and discharge arrangement, the offer can be built around what your facility can actually accept rather than around an assumption.