For Stainless Steel Foot Over Bridge, all fasteners namely Bolt, Nut, Washer, Anchor Bolts, Foundation bolts and DTI-HFSG must be of stainless steel. Normally 300 Sets of these consumables are used with 50-60 foundation bolts in one foot over bridge. Tensile Strength of fasteners should be above 500 Mpa- Tensile Strength & 350 MPa- Yield Strength. oundation bolts should have further strength of 900 MPa. A Bolt consists of a head, a shaft of some length and a threaded end.
Design of the bolt head is important for the amount of torque the bolt will take. Head of the bolt can be hex, screw head, socket head or have another design.
It is based on the application e.g..a flange bolt needs to be long enough to hold a washer, the flange, the flange basket, the companion flange, another washer and the nut, with several threads left over for safety.
It can be coarse (UNC), fine (UNF), or 8 thread (UN-mostly used in oilfield applications), the threads need to be chosen to provide the best load handling characteristics. There are also Metric standard threads, BSW (British Standard Whitworth), and others. Thread selection is important: coarse threads will allow for quicker assembly. Fine threads take longer to assemble, due to the number of revolutions required to travel the same distance as a coarse thread. However, they provide better thread engagement, and more of the mating surfaces are in contact, which provides a more secure connection that can accommodate greater tension in the connection.
*Maximum, unless range or minimum is indicated