## 6.4.10 Bolts and nuts 

Steel bolts and nuts for structural steelwork shall be high strength friction grip galvanized bolts con- forming to ISO 887 or black bolts conforming to DIN 7990. Nuts shall conform to DIN 934. Washers shall conform to DIN 7989. 

High strength friction grip bolts shall be used in conjunction with approved proprietary load indicating washers. 

## 6.4.11 Welding 

All welding carried out during fabrication or erection shall be in accordance with the requirements of TS EN 1011 and as shown on the approved detail drawings. Details of the proposed weld procedures shall be submitted to the Engineer for approval at the same time as the detail drawings. All connec- tions shall be welded in such a manner as to make the finished connections neat and smooth in appear- ance and suitable for painting. All slag shall be removed and all sharp projections shall be round smooth. 

Before welding is commenced either in the fabrication shop or on Site, weld procedure tests shall be carried out in accordance with TS EN 15614 where directed by the Engineer. 

All welders employed either in the fabrication shop or on Site shall pass qualification tests relevant to the weld procedures in use in accordance with TS EN 287-1. Welders shall have satisfactory evidence of having been engaged in welding for at least 9 months in the preceding 12 month period. If the work of any welders employed on the Contract is unsatisfactory, the Contractor shall carry out such further welder qualification tests as are necessary to demonstrate that the welders are proficient. 

Welds shall be subjected to non-destructive testing by processes which may include but shall not nec- essarily be limited to radiographic, ultrasonic, magnetic particle or dye penetrant methods, depending on the type of weld and its position in the structure. The standards of acceptance shall be as defined in TS EN 444, TS EN 583-3, TS EN 1289 and TS EN 1712, unless otherwise agreed with the Engineer. If any work shows defects or fails to comply with the requirements of the detailed drawings or Speci- fication for any reason it shall be repaired or rejected, even though it may have been carried out by qualified welders using approved procedures. 

All welding consumables (electrodes, wire, filler rods, flux, shielding gas and the like) shall comply with the requirements of TS EN 1011. 

Weld electrodes for metal arc welding shall conform to TS 6062 EN 25184 and with the requirements of the appropriate weld procedure. 

## 6.4.12 Fabrication tolerances 

The general tolerance on all dimensions shall be  2 mm. Holes shall be aligned such that fasteners can be freely inserted through the members at right angles to the contact face. Where holes in mem- bers cannot be aligned without damaging or distorting the structure, the member or members shall be rejected unless the Engineer shall permit reaming the holes. 

A structural member shall not deviate from straightness (or from the specified shape) by more than: 

 1/1000 of the lengths between lateral restraints in the case of compression members and beams, or 

 1/500 of the overall lengths (maximum 25 m) in the case of other members. 

