Boltight Ltd, the specialist bolt tensioner manufacturer, has pioneered a fast, accurate and reliable Hydraulic Closure System (HCS) for the temporary tightening of a turbine cylinder casing. Used primarily for saving time when performing rotor clearance, distortion and alignment checks (Tops on: Tops off). The complete system package comprises hydraulic nuts, a hydraulic hose arrangement and a hydraulic pump.
Designed to suit customer requirements, the system requires no modifications or changes to the turbine or the bolting. The hydraulic nuts locate on the existing fasteners and are screwed down on to the casing. A hydraulic harness then connects all of the hydraulic nuts to a pump. When pressurized, the nuts exert a uniform, accurate and repeatable force on the bolts to evenly close the cylinder flange faces.
The HCS provides essential flexibility for the planning of the outage and time savings during the outage.
The HCS is a service tool that does not remain in place during turbine operation. What is significant about the system is its simplicity, accuracy and reliability. It can be used by the customers own site personnel with minimal training. Additionally, as the HCS is used only for performing clearance, distortion and alignment checks during the outage, it compliments the use of traditional tightening methods (e.g. heating and torque) used for turbine disassemble and reassembly.
The HCS performs the outage work scope in a few hours that traditionally takes a few shifts. Additionally, during final turbine assembly and valve cover tightening, the HCS will again provide significant time savings.
Using the Boltight HCS, the ‘tops on tops off’ checks can be completed much quicker and in a safer environment. The system operates at ambient temperature and is designed to meet the requirements of the European pressure equipment directive and the components are CE marked.
Said Boltight Director Fred Heaton: "The Boltight HCS is accurate, repeatable and quick which means that both plant operators and service companies can save time and money when carrying out turbine maintenance. Operational downtime is reduced to a minimum, planning flexibility is improved, and the improvement of measurement accuracy helps to enhance the overall turbine efficiency."