the epocast marine handbook - HA SPRINGER - marine + industrie ...

H.A. SPRINGER GMBH
AN ILLINOIS TOOL WORKS COMPANY EPOCAST MARINE HANDBOOK
The diameter cannot be reduced to less than 80% of the
Minor thread diameter.
reduced dia. (waisted bolt)
reducierter Durchmesser (Dehnschaft)
effective length
effektiv Länge
3.13. To find the bolt torque from a given tension:-
Fv x D
Tp = ___________
5000
Where Tp = Torque in Nm
Fv = Tension per bolt in N
3.14. In the case where bolts are tensioned by hydraulic bolt
stretcher, the engine maker will supply the stretcher,
stating the effective piston face area to enable the re-
quired hydraulic pressure to be calculated. It has been
found there is a loss of tension in the bolt when the
stretcher is released and this factor is a constant between
0.75 and 0.90 dependent on the bolt length. This is
advised by the engine maker. The formula to find the
hydraulic tensioning pressure is:-
Fv
Ph = __________
Ah x K
(Multiply N/mm² x 10 to get bar)
Where Ph = Pressure in N/mm² or MPa
Ah = Area of piston face in mm²
Fv = Tension per bolt in N
K = Tension relaxation constant