INNOVATIVE ANCHORING SOLUTIONS ELIMINATE REWORK
Wind energy infrastructure; be it onshore or offshore, currently relies largely on the use of steel for most of its key components whether it is turbines, towers, foundations, transformer stations and the list goes on.
With that there is a significant amount of work required to take ‘bare’ steel to something that can be used to produce power that can deliver much needed sources of new energy. This work required is nothing new given that steel has been the cornerstone of construction for decades and in particular offshore construction.
THE FABRICATION CHALLENGES
However within the fabrication process it means lots of different types of fastening or bolting is needed to transform the steel into the wind energy power plants. Naturally, the size and type of the connections vary significantly from large pieces of secondary steel such as boat access landing points to lights for illumination within a tower or navigation aids. With the latter herein lies one of the common challenges within the fabrication process.
DEMANDING PRODUCTION SCHEDULES
As anyone who works in this particular area knows that in the perfect world that connections are to be done before the structure heads to the paint shop for coating to be made ready for ‘life in service’. However, this is not always possible as the production schedules are usually quite demanding and the small items that needed to be fastened are left until the latter stages of the production process. So how do you fasten these items to steel after the sophisticated coating system has been applied avoiding costly rework to this system?
SOLUTION
One solution could be the Hilti X-BT stud which is non-weld post paint fixing. This is a blunt tip stud which offers a male threaded connection point after being installed into steel.
THE PROCESS
The stud is installed into steel in a two- step process the first of which involves drilling a small hole into steel using a specific stepped drill bit which is 4.0mm in diameter & 7.2mm deep. Once this hole is completed the stud is driven into the steel using a powder actuated fastening tool.
TESTING
The durability of the X-BT threaded fasteners is also investigated and verified by means of corrosion tests of samples which are exposed for many years to the sea and sea-water environment. For many years they have been used in the Oil & Gas Industry for a variety of applications.
Following comprehensive experimental testing of the X-BT studs they now have gained approvals from GL (Germanischer Lloyd) & DNV (Det Norske Veritas) for use in wind power plants. The certificates were issued in late 2011.
Also as part of the testing it was clearly shown that the effect on the steel base material when the X-BT studs have been installed is less pronounced than the effect of welded studs and noted is that the presence of the studs does not control the fatigue design of the welded tower.
The stud is then anchored to the steel mainly due to friction welding which happens in the installation process. This is because the stud tip is 4.5mm in diameter causing the pre-drilled 4.0mm hole to expand and contract around the stud.
Assuming the base material of the steel is thicker than 8mm there is no damage to the paint work at either the underside of the steel or the point of entry as this is protected by an integrated sealing washer on the stud. The fasteners are made from proprietary austenitic or ferritic-austenitic stainless material allowing the use in C5 environments, e.g. for fastening metal or non-metal grating on off-shore platforms or next to the foundation of off-store steel towers.
60
www.windenergynetwork.co.uk
GL approved the detail category 90 according to Eurocode 3, EN 1993-1-9 and DNV approved the detail category C2 according to the standard DNV – RP- C203. Both bodies allow higher fatigue utilization of the steel when comparing with welded stud connections.
IN SUMMARY
As the wind industry grows innovative ideas or solutions are needed to allow the market to flourish. These innovations can be large or small so long as they can help improve efficiencies to allow the wind opportunity to be developed fully to all our benefits.
Hilti
www.hilti.co.uk
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148