Can I replace screw grd B7 with grd 10.9?

[zulsaid]

Our company is API6D valve manufacturer. I have problem to source hex. socket cap screw with B7 material(this screw use for non pressure part). Can I use grd 10.9 to repalce with B7?

 

[CoryPad]

These materials may be interchangeable, but only you know the part and its requirements. The B7 part is optimized for high temperature applications (its minimum tempering temperature is 593 [°]C, its elongation is 16 % minimum, its tensile strength is 860 MPa minimum), while the 10.9 part is for higher strength at ambient temperature (minimum tempering temperature is 425 [°]C, its elongation is 9 % minimum and its tensile strength is 1040 MPa minimum).

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[metengr]

Be careful here because Grade B7 shows a substantial drop in strength properties above 850 deg F (454 deg C). I would not use Grade B7 above this service temperature.

 

[CoryPad]

For reference, property class 10.9 according to ISO 898-1 will lose 25 % of its strength upon reaching 300 [°]C.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.