ivan,
My Spanish is not real strong so I hope I'm resopnding correctly. If your asking about welder certifiation the reference from D1.1:2002   
4.1.3.1 Welders and Welding operators. The welder's or welding operator's qualifications as specified in this code shall be considered as remaining in effect indefinately unless (1) the welderi s not engaged in a given process of welding for which the Welder and Welding operator is qualified for a period exceeding six months or unless (2) there is some specific reason to question a welder's or welding operator's ability (see 4.32.1)

Remember this is a minimum requirement, many engineers or specification tend add more restriction to these requirements to satisfy there obligations to safety or whatever.

Martin

Hola Ivan

No se a que te refieres con esa  pregunta, dejame ver si entendi.

Que cuando tu te certificas como CWI o certificas a un soldador con AWS D1.1, cuanto es el periodo de vigencia de dicha certificacion?