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Method for Calculating Stud Bolts Length

THEORETICAL LENGTH
L= 2 (s+he+eb+i) + J
s-s´= free threads (1/3 stud bolt diameter)
eb-eb´= flange width
he-he´= nut height (= nut nominal diameter)
i= height of the RF (raised face)*
* (in 150 and 300 series the RF value is 3mm (1/8”) approximated, and it is included in eb height)

Importance of Rolled Threads

Even though the standards usually allow threads to be machined or rolled, this last process is completely advantageous because when thread rolling the pressure over the material does not cut the steel fibers, it reduces material’s surface roughness and it considerably increases fatigue, oxidation and traction resistance. The following drawing shows the increase of surface hardness (HV 10) produced by material deformation.
Note: Rolled threads increase up to 30% its resistance in comparison with machined threads.

 

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