The present invention is directed to a method for removing a higher purity sidestream of a product gas from a main product pipeline gas flow stream of lower purity using a membrane selective for the product gas in contrast to impurities contained in the main product pipeline gas. The process avoids capital intensive apparatus or energy intensive processing and returns the reject gas from the membrane to the pipeline for inclusion with the main product pipeline gas. Recovery of a higher purity component of a main pipeline product gas containing that component is also contemplated.
