ASTM A694 F70 Flanges Manufactured to MSS SP 44

Among all grades of the specification, ASTM A694 F70 has the highest yield strength(70 ksi). ASTM A694 F70 flanges refer to forged low alloy steel Gr.F70 flanges manufactured to MSS SP 44 covering both welding neck and blind flanges sized from NPS 12 to NPS 60 in pressure ratings of Class 150, Class 300, Class 400, Class 600 and Class 900. They are mainly used to connect with butt welding pipe fittings of ASTM A860 Grade WPHY70 or API 5L Gr.X70 line pipes in high-pressure oil&gas transmission services. Since ASTM A694 only designates a loose range of chemical composition and mechanical properties, particular specifications for each grade(F42, F46, F48, F50, F52, F56, F60, F65, F70) shall be specified respectively.

ASTM A694 F70 Flange WN RF 300# 30" XS, MSS SP 44

ASTM A694 F70 Weld Neck Flange RF 30" 300# XS, MSS SP 44.

Chemical requirements for ASTM A694 F70 flanges

Element	Content, %
Carbon (C)	0.06~0.10
Silicon (Si)	0.20~0.40
Manganese (Mn)	1.10~1.40
Phosphorous (P)	≤ 0.020
Sulfur (S)	≤ 0.010
Nickel (Ni)	1.20~1.70
Molybdenum (Mo)	0.20~0.40
Chromium (Cr)	≤ 0.30
Copper (Cu)	≤ 0.25
Vanadium (V)	0.02~0.06
Pcm	≤ 0.25
C.E.	≤ 0.48

*Pcm refers to the cooling cracks susceptible index number which is calculated as:

C + Si/30 + (Mn+Cu+Cr)/20 + Ni/60 + Mo/15 + V10 + 5B

*C.E refers to the carbon equivalent which can be calculated as:

C + Mn/6 + (Cr+Mo+V)/5 + Cu+Ni)/15

Mechanical properties for ASTM A694 F70 flanges

Tensile Strength, MPa, min.	Yield Strength MPa, min.	Elongation %, Min.	Reduction of Area %, min.	Charpy @-46°C J, min.	Hardness HB, min.
600~770	485	18	45	60	156~220

*Heat treatment of quenching and tempering(Q + T) at 620°C shall be conducted.

Views: Author：hbmetals Date:15/12/08