TPi July 2009

Connectors Fi t t ings , Flanges &

means that the coupling has a clamping side and a centring side. When two pipes run together, the upcoming pipe- end is automatically caught and lined up by conical centring rolls. The Standard Coupling has a three-point clamping system that consists of two fixed support feet and one adjustable clamping foot. The adjustable foot bridges thermal expansion and ensures strong clamping inside the pipe. In tests and later experience the Standard Model performed well with smaller diameters up to Ø 30" and under normal circumstances. The following circumstances demand better performance of the coupling: large diameters (higher pipe-weights); thin wall thicknesses (risk of deformation); oval pipes; curved pipes; worn out or uneven support rolls; high velocities of rotation; and high friction forces between pipes.

Advanced Coupling inside a pipe-end S S

result of experience with many different coating processes worldwide.

Technically the Advanced Coupling performs well, but there is one disadvantage. For different wall thicknesses the clamping side can be adjusted very easily, but on the centring side the rolls need to be exchanged or re-positioned. This is not only time consuming, but there is also an extra risk of human error. The wrong rolls can be mounted on the coupling, or rolls can be mounted in the wrong position. To solve this issue the Premium Coupling was developed. This coupling is equipped with a new clamping system that centres both the clamping side and the centring side of the coupling at the same time. When force is applied on the central screw, five clamping feet and centring rolls automatically expand and force themselves against the inner pipe wall. The Premium Coupling can clamp on only 25mm of pipe surface, taking into account the cutback of an internal flowcoat. The coupling combines all advantages in one solution and is the

Dhatec BV – The Netherlands info@dhatec.nl www.dhatec.nl

Premium Coupling with movable centring S S rolls

To improve performance in these harsher circumstances, the Advanced Coupling was developed. This coupling has a five point clamping system instead of three, and all five clamping feet move simultaneously. This ensures perfect centring, stronger clamping and less deformation of the pipe. For an even stronger fixing inside the pipe-end, the clamping feet can be covered with a heat isolating material that also increases the friction factor between the clamping feet and the pipe surface. On the centring side of the Advanced Coupling, there is a pre-centring ring with extra rolls that take the first blows when the pipes are running towards each other. Because of the extra ring the construction of the coupling is much stronger and the extra rolls can handle larger radial movements of the pipes.

Centring and clamping side of a Premium ▼ ▼ Coupling

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July 2009 Tube Products International