When process the deep drilling in unstable soil formations, it is very important to stabilise the boreholes to avoid the hole walls collaption. In this case, the fully casings are good solutions. The casings are designed as doulbe walled, single walled and simplified type without joints.
The double wall casing is in structure of two rolling steel plates with reinforce bar in the middle which gives casings additional rigidity and strength and provides a continuous flush drill string (preventing jamming of drilling tools during insertion and extraction). This is the most popular casings to work with rotary drilling rig, casing oscillator or casing rotator.
The single wall casing is with one layer of steel plate. It is required as per the requests of clients.
The simplified casings are without joints and usually place into the hole permanetely and it is not necessory to reused it.