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 2421 An introduction to pipe jacking and microtunnelling 5 PIPE JACKING PIPES CLAY PIPES Vitrified Clay pipes for microtunnelling and pipe jacking are manufactured to achieve high axial strength. They will withstand the jacking forces used during installation, and the ground loads imposed during their working life. Pipes should be manufactured in accordance with BS EN295-7 and BS EN12889: 2000. They should be obtained from a certified manufacturer, such that they will be supplied from a factory which is quality assured to IS0 9001, and the pipes should be kitemarked. Benefits of clay pipe include chemical resistance and longevity. The pipe ends are machined to produce an accurate joint profile. Collars are typically fabricated from Stainless Steel. The joint will incorporate a rubber seal, most likely EPDM (Ethylene Propylene Diene Monomer). Pipe lengths are usually in the 1.0-2.0 metre range for the more common smaller diameters. As with concrete jacking pipes packers are used to prevent damage to the pipe ends during the jacking process. STEEL PIPES Steel pipes of varying lengths are used as sleeves for the installation of gas, oil and water pipelines where fine tolerances in line and level are not usually required. Factors such as welding time and pit size should be considered when determining the length of each individual pipe. SECONDARY LININGS / REINVERTING There may be certain drives where because of the nature of the ground, the required length of drive, or end use, it is considered desirable to jack a pipe of larger diameter than required as the primary lining or sleeve. The finished diameter is then achieved by either reinverting or by installing smaller diameter secondary pipes. Secondary inverts and pipes can be constructed in a range of materials such as concrete, steel, upvc, or vitrified clay, depending on the material to be conveyed. Secondary pipe linings can be laid in the invert or supported on steel centralisers. Where required the annular space can be filled with a cementitious grout. Typical reinverting and secondary lining detail Clay pipe joint detail Steel cage used in concrete pipes Concrete pipes Clay pipes