Testing And Field Performance Of A High Duty NGL Pipeline Seal

Abstract

An improved multiple seal design was developed for a critical high performance pipeline pumping application with a difficult range of conditions. The pumps are four stage construction, with a 700 hp electric motor and variable speed gear box driven with a range from 2000 to 5000 rpm. The mechanical seal has a nominal balance diameter of 6.5 in, and is a dual seal design with a buffer fluid. The sealed product is a mixture of ethane, propane, butane, and some heavier liquids, and typically ranges from 28 to 37 percent ethane concentration with a mixture of other hydrocarbons and a temperature up to 115 degrees F. The combination of conditions makes this a demanding sealing application. Information is presented on the seal design, development, and test data on a 40 percent ethane NGL mix. The improved seal design has completed over one year service life with very low leakage rates. Field data over the first year of operation is included.