Screws and washers

Fastening systems with bolts and washers are used on the radial and circumferential segments of the connections between the segments of the tunnel lining; they increase shear and pull-out resistance on the connection joints. A complete range of bolts coupled with FAMA’s own threaded sleeves withstand tensile stresses from 70 to 400 kN.

• The length of the bolt is made to design specification.
  
• The thread length on the bolts varies from 115 to 155 mm depending on the type of bushing used.
  
• Bolts are available in different diameters (20/25/28 mm).
  
• The thread pitch ranges from 5 mm to 12.5 mm (rail bolts).
  
• The bolts are made of C40/C45 steel and, at the customer’s request, also of 316L stainless steel or a different grade.
  
• FAMA fasteners are available in different strength grades (ASTM A325, 10.9, 12.9).

When they can be removed, the bolts and washers are supplied unfinished or electrolytically galvanized while permanent bolts are treated with the hot-dip galvanizing process or made of stainless steel. Additional accessories such as HDPE washers, washers with aligners and plain aligners are also available in the range.