A gate valve comprises a valve body, a stem bore which extends through the valve body, a stem which is disposed in the stem bore and which includes a first stem portion that is sealed to the stem bore, a second, smaller diameter stem portion that is sealed to the stem bore, and a gate pocket that is...http://www.google.com/patents/US6923423?utm_source=gb-gplus-sharePatent US6923423 - Small bore gate valve
