Posted to News on 12th May 2009, 00:00
Neeter Drive for ROV Operated Clamp
At a depth 3000 metres below sea level clamp connectors on retrievable chokes are operated by Remote Operated Vehicles (ROVs). Most have inline drive shafts for adjustment, however for some installations the clamp connectors adjusting drive shaft needs to be at 90deg for ROV access. Rather than redesigning the complete clamp mechanism a Neeter Gearbox solution is required.
Retrievable subsea chokes are designed with a retrievable insert. The choke body is mounted on the Christmas tree or manifold. The insert is a unitised cartridge and actuator assembly, which is retrievable to the surface leaving the choke body subsea. The clamp connector is the critical device, which holds the cartridge in place.
When Destec Engineering, based in Lincoln, had a requirement for a clamp connector with a 90deg drive for their ROV they contacted Power Jacks to see if a solution was possible using a Neeter Drive bevel gearbox.
With over 30 years experience in bevel gearbox design and manufacture Power Jacks were able to offer a solution. This solution was designed, developed and finalised with Destec Engineering.
The clamp connector is a three piece, double hinged single bolt design based on field proven hub/clamp technology. This simple rotary clamp make up can be operated either by a diver or an ROV. The Power Jacks neeter drive, bevel gearbox is used for ease of access to the choke drive from above for the ROV to facilitate maintenance.
The Neeter Drive bevel gearbox turns a mechanical drive line though 90° degrees with one or more shaft outputs and are available in solid or hollow shaft designs. Both types have been used on different clamp collar designs with the ultra compact construction of the Neeter Drive range of gearboxes proving ideal when fitting them into restricted spaces.
For this application a special high torque, subsea variant of the Neeter Drive Range-N Series-39 gearbox was designed. The gearbox features precision spiral bevel gears, reinforced drive shafts and of course special subsea sealing with pressure compensation connections.
The Series-39 gearboxes operate on chokes used on subsea installations worldwide in sea water depths up to 3000 metres with operating temperatures of up to 200degC. The choke itself is a highly demanding application, which operates in extremely hazardous conditions. They are designed and built using high erosion resistance materials with a design life in excess of 25 years. So the recommendation to Destec Engineering to use the Power Jacks bevel gearboxes, says a lot about product design and quality of the products.
Currently Power Jacks Neeter Drive, bevel gearboxes are in operation on subsea single bolt clamp connectors on Subsea Retrievable Chokes.
The Destec Engineering subsea clamp connector itself is a field proven design with an excellent track record globally. It's now installed in various installations worldwide and Power Jacks has been supplying bevel gearboxes for them for over 4 years now with ongoing orders. This is a testament to Power Jacks special performance, high quality products "connecting" the two companies to produce first class oil solutions.
