Bevel gearboxes selected for subsea application

At 3000m 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 90 degrees for access by the ROV. Rather than redesigning the complete clamp mechanism a Neeter gearbox is being used.

Retrievable subsea chokes are designed with a retrievable insert. The choke body is mounted on the 'Christmas tree' (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 that holds the cartridge in place.

When Destec Engineering required a clamp connector with a 90-degree drive for its ROV the company contacted Power Jacks to see if a a Neeter Drive bevel gearbox could be used. With over 30 years experience in bevel gearbox design and manufacture, Power Jacks was able to offer design, develop and finalise a design 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 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.

Ultra-compact bevel gearboxes

In this application the Neeter Drive bevel gearbox turns a mechanical drive line though 90 degrees with one or more shaft outputs; customers can choose 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 useful when fitting them into restricted spaces.

For this latest 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 3000m with operating temperatures of up to 200degC. The choke itself is a highly demanding application, which operates in extremely hazardous conditions. Chokes 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 is now installed in various installations worldwide and Power Jacks has been supplying bevel gearboxes for them for over four years now, with ongoing orders. This is a testament to Power Jacks' special performance, high-quality products.

Follow the link for more information about Power Jacks Neeter Drive bevel gearboxes.