With a Bolt Tensioner (SSV), bolts are axially preloaded without torquing using high-pressure hydraulic. Axial tension force has been attained by using SCHAAF SSV for bolts with a thread diameter from 8 mm to over 800 mm.
SCHAAF Bolt Tensioners are distinguished into eight different product groups (PG) (designs) which, in principle, all have the same function.
BOLT TENSIONER (SSV) PG 3
The distinguishing feature of the Bolt Tensioners of product group 3 is that the cylinder-piston-set is placed over a bolt thread and that, then, an immersion nut (puller) which immerses into the Bolt Tensioner is screwed down to the stop face of the piston.
• Flush nut
• For continuous or recessed bolt threads
• Can be used for other thread sizes, by replacing components which depend on thread size
• Short thread overhang of bolt
• SSV is simple to place, thus short set-up times
• Easy handling because of low weight of flush nut
• Larger outer diameter for same technical data as PG 1, 2, 4, 5, 6 and 7
• Difficult handling for thread dimensions larger than 100 mm (4 inch), for overhead mounting
Examples of application
• When different screw sizes on a complete system have to be pre-tensioned using the same SSV
• Universally applicable
FUNCTION OF A BOLT TENSIONER (SSV) PG 3 IN SIMPLIFIED RESPRESENTATION
Place the SSV onto the bolt to be tensioned and screw the thread sleeve down to the piston surface. A hydraulic high-pressure pump, through a flexible hose, feeds oil into the space between cylinder and piston. The hydraulic pressure increases.
Elongation and compression
As the hydraulic pressure increases, the resulting axial force elongates the bolt and compresses the flanges. Thus, the main nut lifts from the flange. On reaching the desired tension, pressurizing is stopped.
Positioning of the main nut
The tensioning force is achieved and the main nut can be turned down to contact the flange. When releasing the oil pressure, the desired tensioning force remains in the bolt connection. After removing the SSV, you may use the equipment for tensioning other bolts.
Bolt Tensioners can be removed from the bolt connection after pre-tensioning.
FIELDS OF APPLICATION
• General mechanical engineering
• Metal industry
• Structural and civil engineering, mining, research technology
• Refineries, chemical industry
• Powerplant technology
• Ship engine engineering, shipbuilding, onshore / offshore
THE ADVANTAGES OF GENERATING PURE AXIAL PRE-TENSION USING PRESSURES UP TO 4000 BAR
• Torsion-free generation of tension force – economical use of bolt material capacity
• Maximum accuracy
• Increased safety
• Non-friction tensioning force application
• Capability to start simultaneous tensioning at multiple points
• Start of tensioning independently of tensioning path
• Quickest test capability at any time
• Universal application
• Saving of time
• Components as per product group specification (cylinder, piston, etc.)
• High-solidity, steel-surface treated
• Hydraulic pressure as a function of pre-tensioning force
• Sealing set for temperature range from -30° C to +100° C
• Connection thread
• Stroke based on thread size and screw geometry
• Stroke indicator
• Piston return stroke boring
• Support sleeve with window for turning the main nut with a setting rod (SSV)
• Support sleeve opening for main nut contact to flange control (SSV)
ACCESSORIES MANUFACTURED BY SCHAAF
• Mounting aids such as locating pin and end attachments, or as requested by the customer
• Turning devices
• High-pressure hydraulic hoses
• Couplings, nipples, adapters, distributor blocks up to 4000 bar
• High-pressure generators: manually operated, electric or air-operated
• Different types of hydraulic oil
It is not always possible to classify all Bolt Tensioners into a specific product group. Please contact us for your special application. In addition to a number of standardized Bolt Tensioners, SCHAAF has already delivered thousands of customized axial Bolt Tensioners. The Design on Demand CAD system allows to realize customer solutions very quickly.
PDF brochure: http://schaaf-gmbh.com/media/_Englisch_Werbematerial/Single_brochures_and_Sheets/02_Bolt_Tensioning/SCHAAF_02,00-Bolt_Tensioning_GB.pdf
SCHAAF GmbH & Co. KG
Bruesseler Allee 22
Telephone: +49 2431 9 77 70 0
Telefax: +49 2431 9 77 70 77