Melvelle Equipment manufactures a range of different sized casing jacks.
Jacking is carried out by cycling the cylinders up and down. Each time, the jaws alternatively grasp the drill pipe, holding the pipe alternatively between the two bowls.
For releasing the jacking loads, if the pipe does not come free from the hole, the jaws can be manually held open to allow the cylinders to retract and release.
With the exception of the high pressure FP-174 series jacks, all other models are designed with a maximum system pressure of 3000psi which is available on most drilling rigs.
It should be noted that if the substantial jacking forces are released as the pipe breaks free, the stored energy in the stretched pipe will result in the pipe recoiling back up the hole with a force equal to the pulling force of the jack.
