Sulzerâ€™s Customer Support Services in Leeds (UK) recently won a contract for a retrofit-upgrade programme in Statoilâ€™s Sleipner gas field based on their ability to achieve a much higher performance in a series of replacement cartridge pumps
This confidence is a result of theÂ development work carried out at Castings Technology International (Cti), with whom Sulzer hasÂ cooperated for several years. Cti has manufactured aftermarket impellers for Sulzer during theÂ development of a breakthrough fast-manufacturing impeller technology. Impellers and diffusersÂ of high surface quality (5mm) and dimensional accuracy (ISO 8062 DCTG5) can be consistentlyÂ attained, leading to minimal machining and less finishing of hydraulic surfaces, reduced weightÂ and improved balance, and higher pumping efficiency.
To meet the needs of the programme, Cti had to manufacture 16 impellers, each weighing 45kg,Â in ASTM A-995 Grade 5A, a nitrogen-alloyed duplex stainless steel. However, to supply theÂ impellers for use in Norwegian oilfields, Cti needed to gain full NORSOK accreditation to the M-650 standard within the short manufacturing timeframe. To the credit of Ctiâ€™s material andÂ manufacturing expertise, full approval was achieved and the programme was completed meetingÂ the performance expectations of both Sulzer and Statoil.
With the first pump now in service, site testing reveals an improvement in pump absorbedÂ efficiency from 75% to 84% saving 10% on the power demand. Improved efficiency from superiorÂ finish and accuracy of dimensions from Cti castings were just some of the tools the SulzerÂ Retrofit team used in re-designing the pump to give approximately double the anticipated benefitÂ in performance.