Type A : cylindrical

Be made of alloy steel and cross sections of the inside and outside pipe are both round.

Type B : spiral

Be made of alloy steel and the outside pipe has spiral grooves.

OD: 79.4-171.4 mm    3-1/8~6-3/4 inch 

yield strength:≥758 Mpa  tensile strength:≥965 Mpa   HB:285-341

177.8-279.4 mm   7-11 inch       

yield strength:≥689 Mpa  tensile strength:≥930 Mpa   HB:285-341

Type C: non-magnetic

Be made of stainless alloy steel with rather low magnetic permeability and the cross sections of the inside and outside pipe are both round

OD: 79.4-171.4 mm    3-1/8~6-3/4 inch 

yield strength:≥758 Mpa  tensile strength:≥827 Mpa 

177.8-279.4 mm   7-11 inch       

yield strength:≥689 Mpa  tensile strength:≥758 Mpa