• Lube Systems
  • Pump Packages
    • Stand Alone
    • Specials
    • FPSO
    • Drop-In
  • Compressor Packages
    • Drop-In
    • Stand Alone
  • Gas Turbines
  • General
• Seal Systems
  • Plan 53B
  • Plan 54
  • Plan 62/32
  • Plan 65
• General Systems
• Kracht
  • Pumps
  • Flow Control
• Actuators
  • Sub-Sea
  • Rotary
  • Linear
• Flushing

Auto top-up system designed to handle the pressure

Essential equipment on pumping systems where hazardous materials are involved, auto top-up rigs come in all shapes, sizes and specifications. The latest unit designed and manufactured by hydraulic systems’ specialist KT Hydraulics is a four-way top-up rig destined for Amerada Hess’ South Arne platform in the Danish sector of the North Sea, where it will run linked up to two pairs of main and booster condensate pumps.

The unit supplies a water/glycol coolant mix to the inner and outer pump shaft seals on each of the two main and two corresponding booster pumps. The KTH / John Crane designed auto top-up rig incorporates twin alarm systems ensuring that any change in pressure within the system – which could indicate a seal failure - triggers an alarm in the control centre. Should the initial alarm be ignored the failsafe activates a secondary alarm and automatically shuts the pump down to prevent any chance of condensate reaching the atmosphere.

To allow for the effects of a seal failure the top-up system has been designed and fully tested to withstand backpressure of up to 450bar, check valves ensuring that condensate from the pipeline cannot escape to the atmosphere through the un-pressurised coolant top-up tank.

The whole rig has to comply with a number of exacting standards due to the nature of its operation being critical to safety and pollution on site. All welding of the 316 stainless steel rig has been carried out to ASME VIII standard whilst design and manufacture complies with pressure equipment directives and KTH’s ISO9001:2000 QA certification.

Design engineer Mike Hogg explains the importance of the newly completed rig in its working environment. “Auto top-up systems are essential on all pump shaft seals where seal failure has to be controlled. Rotating mechanical seals on pumps of this sort of size have to withstand extreme pressures and running continuously as the majority do, the system that cools and lubricates these seals is critical to safe and efficient operation.

The system is really put to the test when a shaft seal fails however. At this point a safe and rapid shutdown of the affected pump and containment of the material being pumped is essential to prevent what could be a catastrophic and dangerous escape of hazardous material into the atmosphere.

The particular unit we have just completed has been commissioned by John Crane Ltd supplier of the pump shaft seals to Weir Pumps on the South Arne platform contract. As soon as this one is shipped out of the factory we will be starting work on a further seven similar auto top-up units, also for the oil industry although this time the oilfields of Oman.”

Designed to withstand backpressure of 450bar the auto top-up rig designed and manufactured by KT Hydraulics will serve two sets of main and booster condensate pumps on the Amerade Hess, South Arne platform in the North Sea.