Sales gas is natural gas that has been processed to meet the strict specifications a pipeline requires before it will accept it for transport and sale. It is the finished product of a gas plant - clean, dry, and within heating-value limits. This guide explains what sales gas is, the specifications it must satisfy, and how raw wellhead gas is conditioned to reach pipeline quality.
Sales Gas in one line: Sales gas (pipeline-quality gas) is processed natural gas - mostly methane - that meets the contractual pipeline specification for water content, hydrogen sulfide, carbon dioxide, hydrocarbon dew point, and heating value. It is the marketable end product delivered from a gas plant into a transmission pipeline through custody-transfer measurement.
Raw gas from the wellhead is not fit for a pipeline. It carries water vapor that can form hydrates and corrode steel, acid gases (hydrogen sulfide and carbon dioxide) that are toxic and corrosive, and heavy hydrocarbons that would condense into liquids in the line. Sales gas is what remains after all of these are brought within a pipeline's contractual limits. Meeting the spec is a contractual obligation: a pipeline will reject or penalize gas that falls outside it.
The point where sales gas enters the pipeline is a custody-transfer measurement point, where the volume and energy content are metered for payment. From there the gas travels the transmission system and is ultimately delivered to utilities and end users. Everything a gas plant does - dehydration, sweetening, dew-point control, NGL recovery - exists to turn raw gas into gas that clears these specifications.
Pipeline specs vary by contract, but the categories are consistent. Water content is limited to a low value (commonly around 7 pounds of water per million cubic feet in North America) to prevent hydrates and corrosion, achieved by dehydration. Hydrogen sulfide is capped very low (often about 0.25 grain per 100 scf, roughly 4 ppm) because it is deadly and corrosive; carbon dioxide is limited (frequently around 2-3%) because it is corrosive and dilutes heating value. Removing H2S and CO2 is called sweetening.
Hydrocarbon dew point is controlled so heavy hydrocarbons will not condense out as liquids at pipeline conditions - this is where NGL and condensate recovery and dew-point control come in. Finally, heating value (energy per unit volume, often expressed as gross heating value or Wobbe index) must sit within a band so the gas burns predictably in end-user equipment; too rich or too lean and it falls out of spec. Sales gas is gas that satisfies all of these at once.
Sales gas is the outlet of the whole processing chain: raw gas enters a plant, passes through inlet separation, sweetening, dehydration, dew-point control, and NGL recovery, and the conditioned residue gas leaves as sales gas at the plant tailgate. The valuable NGLs and condensate stripped out along the way become separate products. Sales gas is metered into the transmission pipeline under a custody-transfer agreement.
The measured variables that prove sales-gas quality include flow and energy at the sales meter, and continuous or spot analysis of water content, H2S, CO2, and heating value. A cloud SCADA such as Merobix reads the sales meter's flow, pressure, temperature, and gas-quality analyzer tags from the site flow computer, gas chromatograph, or analyzer over Modbus, DNP3, or OPC UA. That lets an operator watch sales volume and confirm the gas is staying within spec remotely, and alarm immediately if an analyzer trends toward an off-spec condition.
Raw gas comes straight from the well and contains water vapor, acid gases (H2S and CO2), and heavy hydrocarbons that make it unfit for a pipeline. Sales gas is raw gas that has been processed - dehydrated, sweetened, dew-point controlled, and had NGLs removed - so it meets the pipeline's contractual specification and can be transported and sold.
Typically: low water content (often around 7 lb per MMscf) to prevent hydrates and corrosion; very low hydrogen sulfide (often about 4 ppm); limited carbon dioxide (often 2-3%); a controlled hydrocarbon dew point so no liquids condense in the line; and a heating value or Wobbe index within a set band. Exact limits are set by each pipeline contract.
So the gas burns predictably in end-user equipment like furnaces, boilers, and turbines. If the gas is too rich (too many heavy hydrocarbons) or too lean, its energy content and combustion behavior drift, which can damage equipment or violate the delivery contract. Controlling NGL and inert content keeps the heating value or Wobbe index inside the agreed band.
At the custody-transfer point where it enters the transmission pipeline, using a flow meter and flow computer plus gas-quality analysis. Both volume and energy content are metered because gas is bought and sold on energy. This meter, together with continuous analysis of water, H2S, CO2, and heating value, is what documents that the gas delivered is in spec.
This page references the protocol specifications published by the organizations below. Editions, product capabilities, and documentation change over time - confirm current requirements and specifications directly with the source.
Last reviewed: July 27, 2026. Merobix is not affiliated with, endorsed by, or sponsored by these organizations; their names are used only to identify the standards and products discussed.
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