Our outer coupler can be manufactured for various casing diameters, generally for temporary casings, used in vertical / inclined drillings. What distinguishes it from the classic outer couplings is the sealing gaskets placed underneath the dragging slots. The seal occurs thanks to a gasket which is compressed by a pair of rings. Thanks to M8 screws, it is squized and goes in contact with the drill rod avoiding the leakage of any fluid or cutting. Those, instead will be directed through 4 openings machined specifically under the bell which will prevent their uncontrolled projection in all directions.

The outer coupling is made as follows:

  • Mid body is a piece of Ø219,1x11 made of 42CrMo4 steel tube, the casing threaded side has a 3 starts thread 100 mm long (waved shaped), n°3  "S" shape grooves to receive the internal coupling (sourced from the market) and n°4 holes in the central part dim. 100x100 mm (under the bell) for the bleeding and water escape; 
  • Outer bell is made by a piece of tube 323.9x10 mm welded on round plate 10 mm wall-thickness which is welded to the outer coupling; 
  • Once assembled, the pieces are gas nitruration treated. It is an industrial steel hardenin process, whose purpose is to increase the threads lifetime against the continuously screwing and unscrewing. 

When it is used and its particularity: 

This outer coupler is used in all casing advancing drillings in both vertical and inclined holes. The peculiarity of our product is to allow the operator to drill, reducing to the minimum the problems due to the flushing, made of cuttings or water mixed with cuttings, when drilling in water formations, which are projected on top of the hole.

The uncontrolled cuttings spread is avoided thanks to a serie of gaskets, chosed according to the drill rods diameter. The waterproofing is obtained by a quick action creating the adherence of the gasket to the drill rods, preventing  the uncontrolled and unsafe cuttings flushing that might hit people and the surrounding buildings. In the best case running the risk to make them dirty and at worst to damage them.


Ltm S.r.l. is a company that operates in the field of micropiles, since 1982. The main objective of Ltm is the one of supplying, high quality finished goods, constantly improving the workmanship, so to offer to the clients a superior product.

More about LTM