The complete stud bolt set for the rotor blade connection
of a bolt with two threaded ends, a hexagon head nut, a barrel nut and two washers. Randack, however, did not have to look around in India to find highly efficient anti-corrosion protection for these fasteners. Just 10 kilometres north of the company’s headquarters in Westphalia, Germany, they found the ideal partner in Dörken MKS-Systeme GmbH & Co. KG of Herdecke. Dörken has been developing and producing micro-layer anti- corrosion protection systems here for 30 years and in addition to numerous applications in the automotive industry these are now also widely used in the renewable energy field. Dörken has been active in the Indian market for quite some time, looking after customers from a local office. The company has also already found its first few coating partners in the Indian market.
In-house coating In 2009, Randack decided that it would also do the anti-
corrosion coating with protective zinc flake systems in house, thus keeping the entire manufacturing process – from cutting the raw material to size to coating and final quality control – all under their own roof. In early 2010, a further 3,000 square metres of production space were therefore added, including the company’s own coating plant, which went into operation this year and is supplied with DELTA-MKS®
systems from
Herdecke. The products used are the chrome (VI) free coatings Delta®
-Tone and Delta® -Seal, which have already been used
successfully in wind turbines for over 15 years. All threaded connections fitted in a wind turbine are to
some extent exposed to extreme climatic and thus corrosive conditions, as well as dynamic strains from wind loading and the turbine’s own operation. The fasteners used there are therefore generally highly rigid. However, if the wrong form of surface protection is chosen, these have a degree of susceptibility to brittle fractures. Such brittle fracture failure is often the consequence of hydrogen penetration during the surface treatment process. This is something that needs to be taken into account when selecting the form of anti-corrosion protection to be used. The protective coating also has to have specific friction coefficients in order to enable connections to be easily screwed together on-site even when often working against the clock and under difficult conditions. Not least, however, the coating must provide highly effective and long- lasting anti-corrosion protection. This, of course, applies very especially in the case of offshore locations.
For extreme exposure Zinc flake systems are in effect able to fulfil these requirements as a package. The Delta®
method to choose depends on the size and shape of the parts. Large format steel components, as used in wind turbines, are, for example, coated at Randack by spraying, while smaller elements are given their surface protection by the dip-spin method. As no hydrogen is introduced in the coating process, it is possible to rule out any danger of the rigid components suffering hydrogen embrittlement caused by the coating procedure. After application, the protective coat is annealed for approximately 30 minutes at an object temperature of on average 240°C. The low annealing temperatures prevent the rigid steel components from getting damaged in the process by unduly high heat exposure and thus have a decisive advantage over rival systems.
“ All threaded connections fitted in a wind turbine are to some extent exposed to extreme climatic and thus corrosive conditions, as well as dynamic strains from wind loading and the turbine’s own operation.”
Delta®
The subsequent application of an organic topcoat using -Seal significantly increases the anti-corrosion protection
still further. In contrast to the basecoat, this topcoat is not electrically conductive. The additional protection from corrosion is provided here by insulating the basecoat against corrosive attack. Depending on the choice of topcoat, further requirements can also be fulfilled, such as colouring, chemical-, UV-ray and extreme temperature resistance and defined friction values.
Favourable conditions Setting up an Indian subsidiary for producing solid steel
-Tone basecoat provides
active cathodic protection and, with a layer thickness of just 10µm (depending upon geometry, system set-up and application process) achieves corrosion endurance times as per DIN EN ISO 9227 of over 1,000 hours. The coating can be applied using all standard methods of application. Which
bolts and fasteners not only opened up the possibility for Randack to manufacture cost efficiently in the locality and to supply the leading companies in an expanding market on a just in time basis, but also, where required, to provide on-site technical advice as well. The other general conditions were also extremely attractive. The situation with regards to the supply of raw materials in western India is very good and the Indian labour market also offers great potential in terms of qualified engineers and well trained specialists for operating production plants. This, along with the imported, highly specialised manufacturing equipment from Hagen and innovative zinc flake coating technology from Herdecke, gave the new company the necessary ‘following wind’. Now, 30% of its production is exported to Europe and to parts of the USA. Quality from Westphalia – made in India!
www.doerken-mks.com www. fast f
ixtechnology.com 37
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