In the last 25 years, the natural gas pipeline industry has transitioned from the supplier of clean, dry gas to the mover of billable gas energy; clean and dry or dirty and wet.  The amount of hydrocarbon product that is transported between producer, processor, distributor and user is significant.  To be able to verify the exact composition of the product is important from an economic and product treatment standpoint.  In addition, if the best sampling procedures are followed, the potential for disputes between supplier and customer will be greatly reduced.  The importance of properly determining hydrocarbon gas composition benefits all parties involved.

The United States Department of Transportation (D.O.T.) is a department of the U.S. Federal Government which oversees all issues regarding transportation within the United States of America and U.S. Territories.  Its influence around the world is great and widely respected, but its jurisdiction and power of enforcement is limited to the USA and its territories.  As regards this paper, we will discuss the D.O.T. and its involvement surrounding sample cylinders for the hydrocarbon industry and the rules regarding the movement of these cylinders from point to point in the United States.

The need to be able to take a representative sample of a hydrocarbon product is necessary to ensure proper accounting for transactions and efficient product processing.  The various sampling methods that are available and the options and limitations of these methods are investigated; the most appropriate equipment to use; the reasons for its use and correct installation of the equipment are also addressed.

The sampling techniques employed in extracting a representative sample for crude oil BS&W analysis has received a high level of scrutiny in the last twenty years from concerned oil companies around the world.  The revenue implications are considerable, if the sample is not accurate.  Whether it is pipeline custody transfer, tanker loading/unloading, or refinery input, a representative composite sample of the oil for laboratory analysis is critical.  Plainly put, a 1% error is worth hundreds of thousands of dollars and frequently over a million dollars on one single ship load.  That makes sampling a serious matter in the measurement world for crude oil sales.