I. Heavy Duty Crane Lifting Duplex Crane Shank Hook classification:
1.Strength grade: M, P, S, T, V grade
2.Materials:
M grade with DG20, or DG20Mn
P grade with DG20Mn
S grade with DG34CrMo
T grade below 40t with DG34CrMo, more than 40t with DG34CrNiMo or DG30Cr2Ni2Mo
V grade below 40t with DG34CrNiMo or DG30Cr2Ni2Mo, more than 40t with DG30Cr2Ni2Mo.
link:http://www.chinacranemanufacturer.com/crane-parts/hook/heavy-duty-crane-lifting-duplex-crane-shank.html