Over the past 12 years Apex Hydraulic have been working together with a regular client that own and operate their own fleet of geo exploration vessels to develop hydraulic cylinders for a number of bespoke applications for the offshore tools and rigs that they use. Recently this client commissioned a set of cylinders to fit a new piece of machinery, designed for drilling the seabed.
A Complex Drilling Tool
As the drilling tool is applied to the seabed, it is vital that it applies the correct amount of force; too much can damage the drill and not enough would mean that the drill is working too slowly. The complication is that the amount of force that is required changes as the drill comes into contact with harder or softer surfaces. If the machine is drilling a soft surface with a large amount of force, and then comes across a hard surface and keeps drilling with the same amount of force, this could smash the drill. Replacement tools can cost thousands of pounds – in addition to a vast loss of income due to downtime – so it is vital to avoid breakdowns.
The design of the new tool incorporates a set of six hydraulic cylinders, designed to withstand around 80 ton compressive force each. These cylinders will act as load cells giving out real time readouts of pressure, enabling the machinery to calculate the force applied to the drill tip so it can respond accordingly, avoiding the risk of drill failure.
A Unique Design
Apex Hydraulics produced the six cylinders for the machinery. The power swivel tool has two rings, one at the top and one at the bottom held apart by the 6 cylinders. During use these cylinders are typically to be set at the mid stroke position. As the top drive system starts to push down on the drill string the pressure in the cylinders is monitored to give a live reading of the applied force on the drill itself. As drilling commences, if the drill is cutting well the drilling engineers can apply more load to the drill to help speed it up. Equally if they see that the cylinder pressure is raising too much it allows them to slow the drilling force down to help prevent failure. This feature allows them to drill with an optimised speed without risking damage or downtime. The stroke of the cylinder almost acts like a spring, smoothing out the variations of drilling speeds.
Apex Specifications
The cylinders were designed to have a high capacity but to be short in length, in order to fit the fabrication. They were manufactured for subsea use to around 100 meters, durable for the offshore environment. A bespoke composite spherical bearing was used in the base clevis and composite bushes used in the large forked rod end clevis. The rods were chrome plated 17-4PH stainless steel and the cylinders were coated with three layers of subsea paint. After manufacture, they were tested thoroughly in the inspection department to comply with all offshore machinery requirements.
The manufacture took approximately seven weeks. The cylinders were delivered on time, ready to be fitted to the machinery, complete with certificates of conformity. The client was pleased, once again with the service and quality provided by Apex Hydraulics.
Related Products
The following products were utilised as part of this project. For more detailed information on these products, click on an image below…
