Casing OD114.3 508mm (4 1/2 ∼20) Tubing OD48.36 114.3mm (1.9 ∼4 1/2) Product standard: API SPEC 5CT, SY/T6194 The thread parameter requirement is more strict than API standard by 20%, which gives the product perfect property of anti-galling, anti-slipping and effective performance.