SPECIFICATION AND STANDARD FOR STRUCTURAL STEELWORK: GENERAL PART 8 - BOLTING AND RIVETING

1.11.1       Ordinary Bolts and Nuts

1.11.1.1    Ordinary bolts and nuts shall comply with BS 3692, BS 4190 and BS 4933.

1.11.1.2    All ordinary bolts shall be fitted with washers and nuts complying with BS 4320.  Nut shall be of at least the strength grade appropriate to the grade of the bolt used. Tapered washers shall be used where necessary.

1.11.2       High Strength Friction Grip Bolts

1.11.2.1    The  use  of  high  strength  friction  grip  bolts  and  associated  nuts  and  washers complying with BS 4395 shall be in accordance with BS 4604.

1.11.2.2    Other types of friction grip fasteners may also be used subject to the approval of the Engineer provided they have mechanical properties not inferior to bolts complying with BS 4395 and provided they are capable of being reliably tightened to the minimum shank tensions specified in BS 4604.

1.11.3       Surface Finish

1.11.3.1    Bolt assemblies in externally exposed locations are to be galvanised in accordance with BS EN ISO 1461.

1.11.3.2    In  addition  to  all  other  testing  requirements,  galvanised  grade  8.8  bolts  and galvanised HSFG bolts shall be tested for head soundness according to Appendix 

D9 of BS 3692 and also subjected to supplementary tensile testing to confirm their mechanical properties. Each test is to be carried out on 1% of the total number in each batch of galvanised bolts.

1.11.4       Holes

1.11.4.1    All holes shall be drilled or sub-punched and reamed.

1.11.4.2    Holes for ordinary bolts shall not be more than 2mm greater in diameter than the bolt for bolts not exceeding 24mm diameter and not more than 3mm for bolts over 24mm diameter, unless otherwise specifically required by the design.

1.11.4.3    Holes for friction grip bolts shall be in accordance with BS 4604.

1.11.4.4    Holes for bolts shall be formed by drilling and all burrs shall be removed before assembly.

1.11.4.5    Holes for fitted bolts or pins shall have a diameter equal to or not more than 0.15mm of the nominal diameter of the bolt or pin.

1.11.5       Protection of Hollow Section

1.11.5.1    Where a sealed hollow member is holed by a fastener or pin, provision shall be made to prevent ingress of moisture to the interior of the member. If not shown on the Drawings, the Contractor is to propose the method on the Shop Drawings.

1.11.6       Limits to Length

1.10.6.1    The length of bolts is to be such that at least one clear thread shows above the nut after tightening, and at least one thread plus the thread run out is clear between the nut and the unthreaded shank of the bolt.

1.11.7       Foundation Bolts

1.11.7.1    Foundation bolts shall be cast in to the dimensions shown in the Drawings. The Contractor  shall ensure that  the projecting  ends of  the  bolts  are free  to  move horizontally. The projecting ends of bolts shall be well greased and wrapped in sacking that shall remain in position until the commencement of steelwork erection.

1.11.7.2    Prior to delivery of steelwork for erection, the Contractor shall check the concrete bases or seatings for level, setting out, projection and full degree of adjustment of the holding-down bolts.

1.11.7.3    The Contractor shall remedy any discrepancies or inaccuracies to the satisfaction of the Engineer. Modification to the steelwork, bending of the holding-down bolts or the use of excessive number of washers to accommodate errors in position and projection of bolts shall not be carried out except with the written permission of the Engineer.

1.11.8       Grouting

1.11.8.1    Grout around foundation bolts and under column base plates is to be supplied and placed by the Contractor and is to have a minimum compressive strength at 28 days of 60 N/mm2.

1.11.8.2    The grout mix shall be polymer based, prepared, mixed and placed in accordance with the manufacturer’s specifications approved by SCI.

1.11.8.3    Grouting under the column bases shall only be carried out after a sufficient portion of the steel structure has been aligned, levelled, plumbed and adequately braced by other structural components which have been levelled and are securely held by their permanent connections. Immediately before grouting, the space under the column base plates is to be clean and free of all extraneous matter.

1.11.9       Riveting

1.11.9.1    The use of rivets shall be in accordance with BS 4620.