BOLTIGHT Ltd Hydraulic Closure System
Introduction Following a major overhaul on a conventional steam turbine or a combined cycle steam turbine, the turbine casing is temporarily reassembled to check alignment and clearances between rotating and static components Referred to as tops-on / topsoff work, it involves tightening bolts using a variety of methods This sequence of work is vitally important yet time-consuming
The System The Hydraulic Closure System is a replacement for bolt heating during the tops on / tops off clearance checks The system uses hydraulic nuts on the casing s existing bolts The Hydraulic Closure System is a fast, accurate and reliable method for Tops on: Tops off The pressure of the system is directly proportional to the force applied to the casing Gap measurement can be performed at known casing loads It is a cold system Bolt heating is eliminated so no safety hazards or waiting time Eliminates sub-contract bolting services and standby time costs Minimal training required
System Operation The Hydraulic Closure System is direct retrofit for the turbine casing The hydraulic nuts are installed instead of standard nuts The hydraulic nuts are connected together with high pressure hoses When pressurised, the hydraulic nut system stretches the bolts and quickly, evenly and accurately compresses the turbine casing While the nuts are under pressure, checks can take place When complete simply release the pressure for disassembly No more bolt heating means no more stand by time while the studs cool
Benefits The hydraulic closure system is fast, efficient and reliable It gives accurate and repeatable results Since it is a cold system no safety issues with regards to bolt heating Eliminates stand by time from the cooling of the bolts Uses the existing casing bolts The nuts are designed to fit on the casing s existing spot-faces allowing the system to fit all turbine geometries The Hydraulic Closure System is extremely cost effective, and achieves an even quicker pay back if used on operating plants with identical or similar turbines that have the same bolt sizes and thread forms
Benefits Best Practise Process COST savings BOLTIGHT Hydraulic Closure System Safety Critical path time savings
Time Saving Comparison: Existing method Planned duration 2 x 12 hour shifts comprising: bolt installation; bolt heating: bolt cooling (checks) - bolt heating; bolt cooling; bolt removal. Closure system 1 x 5 hour shift comprising: bolt installation; bolt tightening; - (checks) - bolt removal. Analysis detail: Standard time for hydraulic equipment installation. Fitting hydraulic hoses - 3 hoses per minute Pressurise sequence - 3 minutes Depressurise sequence - 10 seconds Disconnect hoses - 5 hoses per minute
Complete Package At BOLTIGHT we can provide you with the complete system, which includes our hydraulic nuts and all the ancillaries and spares required. The package usually includes hydraulic nuts of varying sizes to suit the turbine casing, an air or electric driven pump, hoses and fittings to harness the system together, spare parts and seals and a comprehensive Health Safety Operating Instruction and Maintenance Manual. We also offer on-site training in use of the system and advice on how best to use the system for complete and accurate casing closure. Rental options are also available on the system.
Product Innovation Size Identification Dots Allows fast and easy recognition of the size of the nut Our engineers can provide you with a colour coded bolting layout diagram to aid nut placement
Product Innovation Lifting Lugs Aids in fitting the nuts to the underside of a turbine case Fast, easy installation Fitted with matching identification dots to the tool size
BOLTIGHT will be pleased to provide a technical and financial proposal for the Hydraulic Closure System. Please don t hesitate to contact us for further details.