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Use this calculator to
torque necessary to achieve a
% of bolt yield.
Use the following Torque Calculator for
B7 and ASTM A320
L7 bolting, as specified in
and 17D for flanges.
TPI for 1"
and smaller are
UNC, 1-1/8" and larger are 8UN.
Some flanges can be over-tightened to the point that the ring groove or
the flange can be damaged.
The following 4 API flanges should not be made up beyond 40,000 psi bolt
stress (tension), due to potentially high flange stress,
and API specifies 40,000 psi stress for all sizes of flanges using
B7M and L7M bolts.
Two coefficients of friction or
f factors, are recognized by API. A coefficient of friction of
0.13 approximates the friction with threads and nut bearing surfaces
being bare metal, or plated, and well-lubricated with thread compound tested in
accordance with API RP 5A3 / ISO 13678.
A coefficient of friction of 0.07
approximates the friction with threads and nut bearing surfaces coated with Fluoropolymer
material (Teflon, Xylan, SermaGard).
For recommended bolt
tightening sequence for flanges, Click Here.
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