Transcription of The Torquing of Stainless Steel - Blacks Fasteners
1 81 The Torquing of Stainless SteelFASTENERSF asteners your guarantee of quality industrial fastenersStainless Steel threads arenotorious for galling or seizingduring tightening. For a successfulassembly, tightening should becarried out with a slow smoothaction. Impact wrenches or airpowered screw drivers are notrecommended. In addition an anti-seize compound must be appliedto the threads. A high qualitynickel anti-seize has been found tobe very torque values arecalculated figures based uponseveral factors including friction,bolt diameter and proof stress.
2 Asthe use of anti-seize is going tovary the friction characteristics ofthe assembly, the actual torquerequired will also the torque valuesquoted can only be regarded as aguide and bench trials should beconducted engineering practicerequires Fasteners to be tightenedto a point where the includedscrew tension is 65-70% of theproof load. Once the proof load isexceeded the bolt will start tostretch permanently. Therefore,during the bench trials the torquerequired to start permanentstretching of the bolt should benoted. Applying 70% of this torquefigure will be a safe Torques for Stainless Steel (304 and316) Metric BoltsGradeGradeA2-70 and A4-70A2-80 and A4-80 Recommended Assembly TorqueRecommended Assembly Torqueto include 70% Proof Loadto include 70% Proof LoadNominal Diameter(NM)(ft lbf)(NM)(ft lbf) few times each year we receivecalls from Fasteners suppliers whoare in conflict with their customerover the quality of Stainless steelbolts and nuts.
3 The customer scomplaint is that duringinstallation the bolts are twistingoff and/or the bolt s threads areseizing to the nut s thread. Thefrustration of the supplier is thatHow To Stop Thread Galling on StainlessFasteners45845 Blacks Bolt body 3/9/06 2:11 PM Page 81
