Steel Buildings in Europe

Part 7: Model Construction Specification 7 - 46 Proposed Clauses Commentary 10.3.2 Nuts shall run freely on their partnering bolt, which is easily checked during hand assembly. Any nut and bolt assembly where the nut does not run freely should be discarded. 10.4 Washers 10.4.1 Washers shall be provided under the nut or the bolt head of non-preloaded bolts, whichever is to be rotated. 10.4.2 For preloaded bolts : - for 8.8 bolts, a washer shall be used under the bolt head or the nut, whichever is to be rotated; - for 10.9 bolts, washers shall be used under both the bolt head and the nut. 10.5 Preparation of contact surfaces in slip-resistant connections 10.5.1 The area of contact surfaces in preloaded connections shall be as specified on the drawings. For contact surfaces in slip-resistant connections shown on the relevant drawings, the following particular treatment shall apply: ... (Insert requirements) . The treated surfaces shall be adequately protected until they are brought together. 10.5.2 Preparation of contact surfaces in slip- resistant connections shall comply with the requirements of § 8.4 of EN 1090-2; special requirements are specified on the relevant documents. 10.6 Tightening of preloaded bolts 10.6.1 The nominal minimum preloading force F p,C shall be taken as indicated on the relevant drawings. Usually, F p,C = 0,7.f ub .A s . 10.6.2 The following tightening method(s) shall be used: ... (insert specific tightening methods) The different tightening methods are described in Table 20 of EN 1090-2. 10.6.3 As an alternative to Table 20 of EN 1090-2, calibration to Annex H of EN 1090-2 may be used: - for all tightening methods; - for all tightening methods, except for the torque method. (choose one of the above options) 10.6.4 When bolts are tightened by rotation of the bolt head, the following special precautions shall be taken: ... (insert special precautions depending on the tightening method adopted) . 10.6.5 For thick surface coatings shown on the relevant drawings, the following measures shall be taken to offset possible subsequent loss of preloading force: ... (insert specific measures, depending on the tightening method adopted) . If torque method is used, this may be by retightening after a delay of some days.