Hauv ntiaj teb kev thauj mus los roj thiab roj av, kev ncaj ncees thiab kev ntseeg tau ntawm cov kav dej yog qhov tseem ceeb tshaj plaws. Ntawm ntau qib uas tau teev tseg los ntawm American Petroleum Institute (API), API 5L Qib X52 (tseem hu ua L360 raws li ISO 3183) sawv tawm ua ib qho ...