A single wiper is releasably and sealably positioned adjacent the lower end an operating string and locked therewith to prevent premature release from the operating string upon manipulation of the operating string. The sealing relationship between the wiper and the operating string prevents communication...http://www.google.es/patents/US5036922?utm_source=gb-gplus-sharePatente US5036922 - Single plug arrangement, lock therefor and method of use
Single plug arrangement, lock therefor and method of use
