M5 X 40 Hex Head Set Screw 8.8 DIN933 BZP

It is important to get the correct tensile strength for the application its being used for as either a higher tensile strength or lower tensile strength may be suitable.  These are usually stamped on the head of the set screw or bolt.  Having a higher tensile strength may not always be suitable on certain applications as movement and stretching of the materials being joined together or the breaking point could be important so always check suitability for specific applications.  Once the fastener has been disassembled it’s advisable to replace all components such as the fastener nuts and washers together with the set screws or bolts.  The reason is that the fastener over time will experience stretching of the threads of when it was tightened up plus the likely constant movement may cause fractures causing weakness to the fastener.

These are bright zinc plated fasteners which is a preventative measure from corrosion.  Avoid breaking into the bright zinc plating usually abbreviated as Bzp as this will cause faster corrosion if not covered with a corrosive protected material as in time this will weaken the fastener.  Also bear in mind using different materials can cause fusing through corrosion especially in damp conditions when mixed with aluminium or stainless steel materials.

More information is available from Central Fasteners regarding fastener details, but its always worth checking with a manufacturer's specifications or drawings if an alternative size, tensile strength or types of nuts and washers are used.