Gas condensate
The cheapest line on the certificate is the one that saves the plant.
Stabilised C5+ condensate into splitters, refineries and crackers — specified on vapour pressure, mercury, organic chlorides and salt, because gravity tells you what the yield could be and those four tell you whether you get to run it.
The desk
A condensate cargo is rarely rejected on gravity. It is rejected on four trace numbers.
Condensate is bought for its naphtha yield, and the yield is visible from the density and the distillation. That part is easy, and it is the part every offer contains. The hard part is that the things which stop a cargo being usable are present in parts per billion and do not appear on a standard crude certificate unless somebody specifically asks for them.
Four of them do nearly all the damage. Vapour pressure decides whether the parcel can be loaded, carried and received at all. Mercury attacks aluminium in cryogenic and petrochemical service and poisons catalysts, at concentrations far below anything a routine analysis would flag. Organic chlorides survive the desalter, convert to hydrochloric acid downstream and corrode overheads. Salt loads the desalter and carries through.
None of these is expensive to test for. All of them are expensive to discover after discharge. So our practice on condensate is to specify them at enquiry, whether or not the buyer has asked — because the buyer who needs them needs them absolutely, and the buyer who does not loses nothing by having them.
Orientation
It is not simply very light crude.
The two are handled by the same desks and carried on the same ships, which encourages the assumption that condensate is crude with a better API. Almost every operational surprise comes from that assumption.
| Crude oil | Gas condensate | |
|---|---|---|
| Origin | Produced as a liquid from an oil reservoir. | Drops out of a gas stream as pressure and temperature fall — at the wellhead, in the separator train, or in a gas plant. Its character follows the gas and the processing, not a crude slate. |
| Yield structure | A full distillation curve with meaningful residue. | Naphtha-dominant with very little residue. That is the attraction and it is also why it is worth little to a refinery configured for conversion. |
| The binding parameter | Sulphur and acidity — a metallurgy and hydrotreating question. | Vapour pressure and trace contaminants — a containment and catalyst question. |
| Stabilisation | Not a concept that applies. | Central. Raw condensate carries light ends that must be stripped before it can be stored or shipped at atmospheric pressure. "Stabilised" is a process claim that requires a number to mean anything. |
| Buyer | Refineries. | Condensate splitters, refineries taking it as a naphtha-rich blendstock, and petrochemical plants taking it as cracker feed. Three different buyers with three different specifications. |
Vapour pressure
"Stabilised" is a claim. A number is a specification.
Vapour pressure governs whether a parcel can be loaded, whether the vessel's tanks can hold it, whether the receiving terminal can take it into atmospheric storage, and how much of the cargo is lost to vapour on the way. It is the first line of a condensate specification and the one most often written loosely.
| Point | Detail |
|---|---|
| The method | ASTM D6377 — vapour pressure of crude oil by the expansion method, reported as VPCRx. It is the method written for crude and condensate, and it is the one to name. |
| The V/L ratio is part of the answer | D6377 runs across vapour-to-liquid ratios from about 4:1 down to 0.02:1, and the result changes with the ratio. VPCR4 is the common reporting basis; a low V/L result approaches true vapour pressure, which is what tank and tanker limits are really about. A specification that says "RVP max" without stating the ratio has left the most important variable open. |
| The temperature is part of the answer too | Typically 37.8 °C (100 °F). If your terminal's constraint is a summer ambient well above that, the number you have been given is not the number that binds you. |
| What we state | Method, V/L ratio and temperature, every time. "Stabilised, RVP 10" is not a specification we would send or accept. |
Mercury
Parts per billion, and it breaks the exchanger rather than corroding it.
The contaminant that justifies this page. Mercury occurs naturally in gas and therefore in condensate, varies enormously by region and field, and does damage out of all proportion to its concentration — by two mechanisms that behave quite differently.
| Mechanism | What it does |
|---|---|
| Amalgam corrosion | Mercury forms liquid solutions with aluminium, silver and zinc. It needs moisture to propagate and it removes material — showing as pitting where the mercury deposits are discontinuous. All aluminium alloys are susceptible to some degree. |
| Liquid metal embrittlement | The more dangerous of the two. Mercury diffuses into the metal structure and the material loses ductility and strength, cracking intergranularly rather than thinning. Because it is a brittle failure, the stress needed to cause it can be very low — so equipment that passes a thickness inspection can still fail. Welds are the worst affected, and magnesium-bearing aluminium alloys are especially vulnerable. The Moomba gas plant explosion originated in embrittlement at a cold box inlet nozzle. |
The numbers are small. Industry practice puts a general protective limit around 5 ppb, and complete removal — to the order of 0.1 ppb — where brazed aluminium heat exchangers are in the circuit. Those are concentrations that no routine crude assay would ever surface.
Determination is by dedicated methods — ASTM D6350, D5954 and D7623, and ISO 6978 — not by a general metals scan. Where mercury is present, removal is a plant matter: silver-impregnated molecular sieve, or non-regenerative metal sulphide beds at the inlet.
Why this sits on a supplier's page rather than a buyer's. A cracker or a cryogenic plant knows its mercury exposure precisely and will specify it. A refinery taking condensate as a naphtha blendstock often will not ask — and may still have aluminium in a downstream unit or a customer who does. The cost of putting mercury on the certificate is trivial. The cost of the one cargo where it mattered and nobody looked is a plant outage.
So we report it where the destination is a splitter, a cracker or any cryogenic service, and we offer it everywhere else.
Chlorides & salt
The desalter does not catch the ones that matter.
Two different contaminants that get discussed as one, with the result that a specification often controls the harmless one and misses the damaging one.
| What it is | What happens | |
|---|---|---|
| Inorganic chloride (salt) | Sodium, calcium and magnesium chlorides carried in entrained produced water. | Removed by the desalter, which is what a desalter is for. Loads the unit and carries through when the load is high, but it is a known and managed quantity. |
| Organic chloride | Chlorine bound into hydrocarbon molecules — not naturally occurring in meaningful quantity, and typically the fingerprint of something added upstream, such as a solvent or a cleaning chemical. | Passes straight through the desalter. It converts downstream to hydrochloric acid, which attacks piping and overhead systems and contaminates units far from where it entered. This is the contamination mode that has closed refineries and given rise to pipeline contract clauses limiting it. |
Destinations
Three buyers, three specifications.
The same parcel is worth different money to each, and each cares about a different part of the certificate. Telling us which you are is most of the enquiry.
Condensate splitters
Built for exactly this feed and run on the distillation curve. They care about naphtha cut yield, and they care about mercury and chlorides because they have nowhere to hide them.
Refineries
Taking condensate as a naphtha-rich blendstock into a crude slate. They care about how it behaves blended, about vapour pressure in their tankage, and about not upsetting a unit tuned for heavier feed.
Petrochemical plants
Cracker feed. The strictest on trace contaminants, because cryogenic sections and brazed aluminium exchangers are exactly what mercury destroys, and catalysts are what it poisons.
The specification
What we report on every condensate parcel.
The standard set, with the method named. Where a destination does not need a line, it costs nothing to have it; where it needs one and it is absent, the cargo cannot be assessed.
| Parameter | Method | Why |
|---|---|---|
| Vapour pressure | ASTM D6377, with V/L ratio and temperature stated | Containment, loading, storage and vapour loss. The first line. |
| Density at 15 °C / API | ASTM D4052 or D1298 | The headline, and the input to yield. |
| Distillation | Full curve where available | The actual naphtha yield. What a splitter is buying. |
| Total sulphur | ASTM D4294 | Hydrotreating load and product sulphur. |
| Mercury | ASTM D6350, D5954 or D7623; ISO 6978 | Aluminium embrittlement and catalyst poisoning. See above. |
| Organic chloride | ASTM D4929, part stated | Downstream HCl corrosion. Not covered by a total-chlorides figure. |
| Salt content | Named per cargo | Desalter load. |
| Hydrogen sulphide and mercaptans | UOP 136 | Vapour-space safety at both ends, and odour complaints that become regulatory ones. |
| Water and sediment | ASTM D4006 and D4007 | What you pay freight on, and the outturn basis. |
| Copper strip corrosion | ASTM D130 | General corrosivity as presented. |
Carriage
The cargo you load is warmer than the cargo you specified.
Condensate is the product where the gap between the certificate and the delivered parcel is most often a physics problem rather than a quality problem.
| Item | Position |
|---|---|
| Loading temperature | Vapour pressure rises steeply with temperature. A parcel accepted on a figure measured at 37.8 °C and loaded appreciably warmer is, in the tank, a different cargo. Loading temperature is recorded and it belongs in the documents. |
| Vessel and tank arrangement | Clean product and parcel tankers according to lot size, with tank venting and pressure arrangements suited to the vapour pressure actually presented, not the nominal one. |
| Vapour loss | Light ends leave. Whether that loss sits with buyer or seller, and against which measured figure, is a contract term worth settling before it is discovered. |
| Previous cargo | Three-cargo history requested as standard. Condensate is pale, clean and low-viscosity, and it picks up whatever the tank last held far more readily than a crude would. |
| Quantity | Ship's figures, shore figures and the vessel experience factor, with the governing figure named in the contract rather than assumed. |
| Inspection | Independent at load and discharge, sampling under supervision at a point agreed in advance, temperature recorded with every sample. |
Scope
What we do and what we do not.
- What we supply
- Stabilised gas condensate as seaborne cargo parcels — FOB, CFR, CIF or delivered to a nominated terminal — with independent inspection and the full certificate above.
- We are offtakers, not producers
- The same position as on crude. No equity in production, no operatorship, and no representation otherwise.
- We do not stabilise, split or treat
- We do not operate stabilisation units, splitters or mercury removal beds. Where a parcel needs treatment to meet your specification, that is a plant matter and we will say so rather than implying we can adjust it.
- We do not warrant your yields
- We give you the distillation and the trace analysis. What your splitter or your cracker makes of it is yours to model.
- Origin
- Screened per consignment on the same basis as crude — chain of title, vessel, AIS continuity, ship-to-ship history and counterparty. Where it cannot be cleared we decline. See Compliance.
How to specify
Six lines and we can price it properly.
Condensate enquiries usually arrive as an API and a tonnage. These six make them answerable.
Which plant it feeds
Splitter, refinery blendstock or cracker feed. This sets the whole specification and most of the value.
Vapour pressure limit, properly stated
Maximum, with the V/L ratio and the temperature. And the ambient your terminal actually sees, if it is warmer.
Mercury ceiling
In ppb, and whether you have brazed aluminium or cryogenic service anywhere downstream. If you are unsure, say so and we will report it regardless.
Organic chloride ceiling
Separately from salt, by ASTM D4929. A total-chlorides number will not do.
Yield expectation
The naphtha cut you are buying, and the distillation range you need it across.
Parcel size, basis and terminal
Tonnes, FOB / CFR / CIF / delivered, receiving tankage and its pressure rating, and vessel restrictions at the berth.
Quality
Sampled cold, sealed, and kept.
Inspection by an independent agency appointed for the cargo — SGS, Bureau Veritas or Intertek — instructed jointly, at load and discharge, with the quality and quantity determination points named separately in the contract.
On condensate the sampling discipline is its own subject: a sample that loses light ends between the tap and the laboratory reports a vapour pressure the cargo never had, and reports it low. Pressurised or chilled sampling, minimal transfer, and prompt analysis are not laboratory fussiness — they are the difference between a certificate and a guess.
- Certificate of quality
- The full parameter set in the specification table, each with its method designation and, for vapour pressure, its V/L ratio and temperature.
- Trace analysis
- Mercury and organic chloride by their dedicated methods, not inferred from a general scan.
- Missing determinations
- Chased or independently run before offer. A blank on a condensate certificate is usually a blank in exactly the place that matters.
- Retained samples
- Sealed retains at both ends, held under conditions that preserve the light ends rather than quietly releasing them.
- Documentation per parcel
- Certificate of quality, certificate of quantity, certificate of origin, safety data sheet, bill of lading, loading temperature record, three-cargo tank history and the independent inspection report.
Straight answer
What we will tell you before you ask.
- That "stabilised" on its own means nothing
- It is a description of a process, not a property of the cargo. Without a method, a V/L ratio and a temperature, it is a word. We will not send it as a specification and we would query it in one.
- That we will report mercury whether or not you ask
- Because the cost of the test is negligible and the cost of the cargo where it mattered is an outage. If you have aluminium or cryogenic service downstream, tell us and we will treat it as a binding ceiling rather than a data point.
- That total chlorides is the wrong test
- The organic fraction is the one that passes the desalter and becomes acid downstream, and it needs ASTM D4929 with the part named. A comfortable total-chlorides number has reassured people who then had a problem.
- That the sample can lie about vapour pressure
- Always in the same direction — low. Sampling technique on this product is part of the specification, and we will tell you how a figure we are quoting was obtained.
- That the three buyers are not interchangeable
- A parcel that is excellent cracker feed can be an awkward refinery blendstock, and the price difference is not arbitrage. We will place a cargo where it belongs rather than where it moves fastest.
- Where an origin cannot be cleared
- Screened per consignment, declined where it cannot be documented, and not passed onward — see Compliance.
Enquiries
Every enquiry is answered by the desk that handles it.
Send the product, quantity, delivery basis, destination and timing. We revert with availability, an indication and the documentation that accompanies it. Specifications are released once we know who we are speaking with.