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JapaneseHDPE PIPE Information 3
Transport
Simply the transport of a single pipe with a total length of 5.50 m and a weight of about 16 tonnes cried out for the use of a flatbed truck, which had to be carried out with police accompany and support vehicles. The distance between the production hall to the installation site was about 70 km for which each individual transport took 65 hours. The normal highway could not be used for some lower bridge heights. Fortunately, a special route could be found to make the transport as efficient and economical as possible.
Preparations of two pipe strings onshore
The participating companies calculated an ideal scenario for man, machine and nature on site by the splitting of the 84 m total length in two sections of each 42 meters. All construction methods and installation procedures for welding, lifting and sinking were selected based on these parameters. The two pipe parts were welded into sections of 42 meters each. The pipe ends needed to be connected to each other on one side and to the above mentioned concrete basins on the other.
Jointing of the pipes
The pipes were transported on site with a mobile crane with a crane capacity of up to 100 tones. Various trapezoidal structures and scaffoldings had to be moved and adjusted for the welding processes. Preliminary work, which is indispensable and important before welding, was carried out with a high worload. The electro fusion welding was carried out by a special welding equipment and procedure for large pipes, designed by Krah AG. This electro fusion welding procedure was not the standard Krah Electro fusion method, it was a special one based on Krah outfall application experience.
Nevertheless, there was a special support offered by Krah AG by providing a welding engineer, which was assisted by a welding specialist of Krah Americana Latina, besides these two welding experts.
To place the pipes before welding in the correct position in a longitudinal direction, two newly designed steel crosses were installed on the respective pipe ends. Several steel ropes were strained through drawstrings in these steel crosses, centrally and at the sides. They provide the correst positioning and fixation of the pipes before the welding.
The time for joining two pipes with each other by integrated electrofusion took only 5 hours, includingall preparation.
An inner and an outer heating wire allowed a welding according to the electro fusion method and created a homogeneous pipe line. This pipe line has been completed by an additional inner and outer seam according to the extrusion welding process. The intensive adjustment works and preparations demanded the main time because the pipe geometry of the stored pipes, contrary to the previously produced sample pipes in the production hall, were exposed to temperature changes from +10 to +50 degrees C.
article source:
Handbook on large plastic pipe
