Abstract: Clarified up in the paper are the main revisions of the technical contents as described under the API specifications for tubing and casing,i.e.,API Spec 5CT,API Spec 5B,API RP 5C5,and API TR 5C3,and the new contents are summarized in terms of material performance,consistency,dimensional accuracy,quality assurance system,and requirement for the API monogram.It is suggested that manufacturer concerned positively get familiar to the technical content revisions as made in the specifications as above mentioned,and accordingly update relevant measurement and inspection equipment without any delay so as to meet the requirements as specified under the edition-revised API applicable specifications for such parameters as average OD,average WT,thread middle diameter and ovality,etc,and accordingly properly control the manufacturing processes so as to further improve the performances of the OCTG products,and the accuracy of prediction of their reliabilities,and moreover strictly control the production quality in accordance with the old and new technical requirements under all the said API specifications.