8.4 Welding and cutting of steel elements (p. II)
a inside weld (only over a length of 500 mm at the top and the toe)
8.4.4 After welding the procedure for checking the position of the connectors on tubular primary elements shall be as follows (see figure 8):
- position the element on a horizontal plane and rotate it such that line P at top end of the element is horizontal;
- by using levelling techniques mark the position T on the element at the third points along the length and at the lower end of the connectors as indicated in figure 8;
- check compliance with the following tolerances at the top end, the third points and the lower end of the connector:
- L = (πDr) / (4 ± 10) mm;
- R = (πDr) / (4 ± 10) mm;
- L and R are measured along the outer circumference of the element;
- Dr is the outside diameter of the primary element at the checked sections.
- a top of the element and connectors
- b toe of the element
- c connector
- d toe of the connectors
- e third points on the connectors
- l length of the connectors
- T top of the element as established by levelling
- P line connecting the centres of both connectors at top end of the element
8.4.5 Electrodes shall be in accordance with EN 499:1994.
8.4.6 The metal deposited by welding shall, as a minimum, have the mechanical characteristics equivalent to those of the base material.
8.4.7 Quality Steel (QS) according to EN 10248-1:1995 and steel grades S420xxx and S460xxx according to EN 10219-1:1997, shall be welded using basic filler metals with low hydrogen. The level of hydrogen in the deposited metal shall be ≤ 10 ml/100 g.
8.4.8 In order to prevent all risks of cracking, preheating temperatures shall take account of the steel carbon equivalent, the welding process and the type of joint.
The temperature of a weld shall be ≤ 250 °C before the next welding pass is started.
Preheating shall extend for at least 75 mm on each side of the weld.
NOTE Preheating temperatures for different thicknesses and steel grades are given in table B.3.
8.4.9 Special care shall be taken in order to ensure that the stresses and distortion due to the welding are minimised.
8.4.10 Welds of acceptance class D according to EN 25817:1992, shall be carried out by experienced operatives.
8.4.11 Welds of acceptance class C according to EN 25817:1992, shall be carried out by operatives qualified in accordance with EN 287-1:1992 + A1:1997.
8.4.12 The tolerances of sheet piles and primary piles lengthened either by butt welds or by splice plates shall be in accordance with EN 10248-2:1995, EN 10249-2:1995 or EN 10219-2:1997 referred to in clause 2.
8.4.13 The tolerances of strengthened sheet piles and primary elements shall be in accordance with EN 10248-2:1995, EN 10249-2:1995 or EN 10219-2:1997.
8.4.14 The tolerances of corner piles, straight web junction piles, box piles and fabricated primary elements shall be in accordance with EN 10248-2:1995, EN 10249-2:1995 or EN 10219-2:1997.
8.4.15 Where steel sheet piles are to be spliced by butt welding, the interlock may be left unwelded, unless a seal weld is required or if it is specified in the design.
8.4.16 Where possible, butt welds should be located at a position in the pile length which is well removed from the location of the maximum bending-moment section. In addition butt weld positions in adjacent piles should be staggered by at least 0,5 m in the driven wall.
8.4.17 Sheet piles shall not have sudden variations of the section in the longitudinal direction of the pile. Plates, strips, splice plates and partial sheet piles for strengthening, shall be chamfered (see figure 9).
- A pair of strengthened sheet piles
- b chamfered partial sheet piles
8.4.18 Testing and inspection of welds shall be in accordance with table 1.
8.4.19 If strengthening of the sheet pile is specified, the method should take account of the expected driving conditions.
NOTE The strengthening details depend mainly on the presence of obstructions in the soil. Figure 10 gives an example of a simple strengthening method for the head and toe of a double U-pile.