Digitized mobile process-reliable and safety bolting of high torque bolt joints in the wind power industry means cost savings - Author: Patrick ...
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Digitized mobile process-reliable and safety bolting of high torque bolt joints in the wind power industry means cost savings Author: Patrick Junkers – HYTORC–Barbarino & Kilp GmbH Krailling / near Munich – Germany – Short Version
Facts about onshore & offshore wind turbines Regular inspections and maintenance are necessary for wind turbines in order to avoid costly system failures and to ensure operability. Bolted joints must also be checked to determine whether there are any impermissible changes compared to the approved version. Checking the preload is an essential test criterion, because self-loosening of bolt-joints is a high safety risk. That means short and therefore expensive inspection intervals on bolt-joints. The knowledge of the real preload force-time behavior of planned preloaded bolting- connections enables the design and construction of low-maintenance /-free flange connections for wind turbines. Operating costs can be reduced through longer inspection intervals, costly checks can be reduced, or the replacement of complete bolt-joints can be prevented. The work and plant safety as well as the operating costs of wind turbines can be significantly optimized 18.09.2020 2
Which bolt-joints are used in wind power? HV - bolt sets High-strength pre-loadable bolt-joint-sets (Set = bolts + nut + washers) with corrosion protection usually Hot-dip galvanizing (tZn) Strength class 10.9 with thread tolerance 6g + tZn HV nuts, property class 10 with 6AZ thread oversize. In the factory under process conditions with a Lubricant coated based on MoS2. The internal thread of HV nuts is not hot-dip galvanized and is only protected against corrosion by the applied lubrication. HV washers: hardness class 300HV - 370HV with bevel. 18.09.2020 3
Torque-controlled bolting Where does the torque value originate from ? But bolt manufacturers also give recommendations for torque values, which is then used as a technical specification. 18.09.2020 4
Why can bolt-joints fail? Technology as a factor!
- Incorrect design and calculation of the bolt-joint
- Low strength of the nut or bolt (quality)
- Thread tolerances too big
- Slight inclination of the Nut contact surface
- Reaction problems when tightening or loosening nuts and bolts
- The coefficient of friction is too low or too high
- - due to impermissible additional lubrication of the individual components
- due to incorrect application of lubrication from the bolt manufacturer
- when bolts and nuts get moist / wet lubricants tend to absorb water
- due to improper transport and storage the bolts and nuts
18.09.2020 5
Conclusion: To tight or to loose a bolt-joint connection is a complex
process! (see Ishikawa-Diagram)
Determining Factors for R&D activities:
Losses through
Friction Component
Settlement
Lubrication Material Hardness
Tightening Speed Lack of Training Lack of Training
Surfaces Component Clearance Gaps Geometry Hydrogen Embrittlement
Paint / Coating
Temperature Surface Pressure Size Accuracy
Drill Hole Gaskets / Seals Rolling Defect
Humidity Coating Joint Parts Material Defect
Wax Cracks
Surface Humidity Joining Method Surface Defects
Temperature Tightening Speed Phosphor Diffusion
Lack of Training Grip Length Ratio Shrinkage Cavities
Connecting Tightening Method
Specified Control Unit Surface Waviness Target Unit
Torque / Angle / Force / … Measurement Method Bolt Load
Tightening Method-Tools
Hardness Circumstances Length of Cycle Reaction Method
Process Reliability
Thermal Capacity
Tightening Method Fixation Available Space
Error recognition
Dimensions Cleanliness
Surroundings Supply Driver / Operation Method Bolting Time
Safety Standards and Norms Rework Standard Requirements
Back-Up Wrench Accuracy
Calculation Drawing Requirements Error Detection Assembly
Work Area Reliability
Engineering Manufacturing Tool
18.09.2020 6
Since February 2015: Guideline VDI / VDE 2862 – Part 2 „Minimum requirements for application of fastening systems and tools” The VDI/VDE-2862-Part 2 serves as basis for the use of fastening systems and tools in all fields of plant construction and mechanical engineering. It defines joint types ( A, B or C ) and the minimum requirements applicable to the assembly tools used. This standard applies to all fastening locations or threaded fasteners in equipment manufacturing, plant construction and mechanical engineering, and also to the assembly of flanged connections in components under pressure. It concerns all entities or companies involved in the manufacture, assembly, maintenance and repair of equipment, installations or machines. Definations of categories: Category A – High risk, danger to life and limb or to the environment Category B – Medium risk, operational malfunction or system shutdown Category C – Low risk, non-critical 18.09.2020 7
Guideline VDI / VDE 2862 – Part 2
Minimum requirements for applications of fastening systems and tools for Category A – High risk,
danger to life and limb or to the environment.
- Directly measured control factor (e.g., torque, rotation angle, elongation)
- Directly measured monitoring factor (e.g., torque, rotation angle, elongation)
- Redundant design of a measurement sensor for direct acquisition of the control and / or monitoring
variables. Note: This can be also be achieved with a plausability check.
- Control factor and monitoring factor must not be identical
- Fastening results made available for further processing
18.09.2020 8
Guideline VDI / VDE 2862 – Part 2
Minimum requirements for applications of fastening systems and tools for Category B – Medium
risk, operational malfunction or system shutdown.
- Directly or indirectly measured control factor (e.g., torque, rotation angle, elongation)
- Directly or indirectly measured monitoring factor (e.g., torque, rotation angle, elongation)
- Control factor and monitoring factor must be available
- Fastening results made available for further processing
Minimum requirements for applications of fastening systems and tools for Category C – low risk, non
critical
- directly or indirectly measured or acting control variable
(e.g., torque, rotation angle, elongation, pressure)
18.09.2020 9
Conclusion: bolt joints should be tightened at least after Torque-controlled / angle-monitored tightening-method (DGD) hydraulic bolting methods with Data Recording: DGD = Torque-controlled, angle monitored tightening The control value in this assembly method is the target torque, and the reached rotation angle is the reference value at the end of the bolting-process DGA = Torque-controlled tightening (indirect) DDW = Torque & Angle controlled tightening DGS = Torque-controlled, yield-point monitored tightening SGD = Yield-point controlled, angle monitored tightening SGA = Yield point controlled tightening 18.09.2020 10
01 piece short videos: Tigthening bolt-joints M30 = SW 46mm Torque-controlled/angle-monitored DGD with 1.650 Nm 18.09.2020 11
All curves of three tightening processes each with 1,650 Nm
torque-controlled - rotation angle monitored DGD
All curves with Reaction arm
18.09.2020 12End results of three tightening processes each with 1,650 Nm torque-controlled - rotation angle monitored DGD Bolting-Results with Standard Reaction arm 18.09.2020 13
How about saving costs and increasing quality? …to reduce costs and increase quality at the same time! And this is where standard bolted joints bear a great, so far untapped potential by using new mobile and intelligent bolting systems, which are being operated and tested and suitable for on-site applications. 18.09.2020 14
Saving costs and increasing quality by using hydraulic yield-point controlled tigthening Mobile hydraulic yield point controlled tightening This takes advantage of the fact when tightening bolted joints by means of mutual torsion of the nut and the bolt not only axial, but also torsional stress is applied as a result of thread friction. Yielding of the bolt starts when the reference stress of tension and torsion reaches the material’s yield point. Immediately after the preload is applied, 50% of the torsion in the bolt is reduced. Therefore, the reference stress decreases, while the preload remains and the yield point controlled preloaded connection re-gains an elastic condition. 18.09.2020 15
How does hydraulic yield controlled tightening (SGA) work in practice? In order to fasten HV bolted joints with yield point controlled tightening in a process- reliable way in the field, and to meet all the requirements from VDI/VDE2862-2 in the sense of Industry 4.0, a mobile, practical, hydraulic tightening system is made up of a process and documentation pump combined with standard hydraulic torque wrenches with angle sensors which record, analyze and monitor all tightening processes. 18.09.2020 16
How does hydraulic yield controlled tightening (SGA) work in practice? Mobile, field-proven yield point controlled tightening with hydraulic standard square drive and low clearance Torque-Wrenches quasi as „a source of power“ from 60 Nm to 190,000 Nm with removable angle sensors (for process reliability) 18.09.2020 17
01 piece short videos: Tigthening bolt-joints M30 = Hexsize 46mm Yield controlled tightening - SGA 18.09.2020 18
All Curves hydraulic yield controlled tightening (SGA)
Tightening of bolted joint-
connections M30 = AF= 46mm
hydraulic yield controlled -
SGA
18.09.2020 19All results hydraulic yield controlled tightening (SGA 18.09.2020 20
Elongation measurement results of three tightening
processes, yield controlled tightening (SGA)
Nulllänge (L0) - [mm]
182,08 184,06 183,24
Zero Measurement (L0)
Vorgesp. Länge (L1) - [mm]
182,85 184,92 184,18
Preloaded Bolt Length (L1)
Unversp. Länge (L2) - [mm]
182,22 184,15 183,41
Untightened Bolt Length (L2)
ISO 4017 ISO 4017 ISO 4017
Schraubentyp M30 x 3,5 M30 x 3,5 M30 x 3,5
Fastener Fk: 10.9 Fk: 10.9 Fk: 10.9
Plastische Längung in %
0,0760% 0,0488% 0,0928%
Plastic Elongation [%]
18.09.2020 21Meaning of the abbreviations in reference to the
elongation measurement results
1
The LK’ = effective plastified clamping length
1 = for bolts
2= for threaded studs
Needed for calculating the plastic elongation in %
2
18.09.2020 22Hydraulic yield point controlled tightening (SGA) Practical example from wind power Onshore wind turbine tower flange with M64x300mm-10,9 = hex size 100mm with HYTORC hydraulic torque wrench HY-20 MXT yield point controlled tightening. This bolted joint required a torque of: 18,805 Nm The linear pitch was: 147.5 N per degree 18.09.2020 23
Hydraulic yield point controlled tightening (SGA) Practical
example from wind power
2
5
6
Complete log of all onshore wind turbine tower flanges tightened with yield point
controlled method. M64x300mm-10,9 = hex size 100mm. ALL bolted joints had a yield
point under Rp0,2
18.09.2020 24Hydraulic yield point controlled tightening (SGA) detection of performance
thanks to statistical data
Statistical SGA evaluation of the values applied individually from bolt to bolt: linear slope; Torque and Angle
of rotation
1). The Reason - here: Significantly increased coefficient of friction
recognizable by the linear gradient (Nm per degree) (Bolt No. 14 can be
recognized by the X axis)
2). The Consequence / Result - here: increased torque recognizable
by the torque statistics (Nm) (Bolt No. 14 can be recognized by the X
axis)
3). Indication of the location of the process-failure
(Bolt No. 14) Here: in the bolt thread because of higher torsional stress.
SGA switches off due to the comparative stress (= torsional stress +
axial load). Can be recognized by the angle of rotation statistics (°)
18.09.2020 25Advantages of hydraulic yield point controlled tightening a). Tightening factor αA Does not apply for the yield point controlled tightening, because it is not possible that bolted joints can break. Please see VDI-2230 November 2015 Table A8, page 120 - Comments b). Max. preload force: Due to the tensile and torsional stresses, the bolt reaches its individual yield point during tightening. As the torsional stress discontinues at the end of the tightening process, a preload force of approx. 90% of Rp0,2 is reached. c). Independent of friction value: Every bolt is stressed to the yield point independent of the friction. Different thread friction coefficients merely lead to a change of the torsional stress in the bolt. d). No customized bolts required: The tightening method can be applied both on the bolt head as well as on the nut. 18.09.2020 26
Advantages of hydraulic yield point controlled tightening h). Meets VDI/VDE2862-2 Meets the requirements of VDI/VDE2862-2 for tightening bolted joints. i). Documentation in the sense of industry 4.0: Each tightening process is documented with torque and angle in the form of text and graphics and with a statistic. j). Quality control: Not only the bolt, but the entire joint is “measured” during tightening, quality deviations are detected immediately. k). Fatigue strength Due to the high preload level, the joint’s fatigue strength also increases. l). Process-reliable tightening even of varnished components. 18.09.2020 27
Advantages of hydraulic yield point controlled tightening e). Reusable: As the method safely switches off before Rp0,2, the bolts can be reused. f). Selection of different bolt manufacturers Bolts and nuts from different manufacturers can be mixed. As each bolt is tightened to its individual yield point, there are no limitations when it comes to choosing the bolt suppliers. g). Lowest relaxation As all components are constantly in a state of force flow and an especially high preload force is reached, this tightening method has the lowest relaxation. h). Accepted method Yield point controlled tightening is accepted by all certifying bodies and in VDI-2230. 18.09.2020 28
Hydraulic yield point controlled tightening process (SGA) - approved by DNV-GL Hamburg since March 2019 18.09.2020 29
Saving costs and increasing quality by using hydraulic yield-point
controlled tigthening
Even coated components can be fastened in a process-reliable way with ECO2Touch and
yield point controlled tightening!
See publication of research project at Offenburg University of Applied Sciences at the ASME Congress, Phoenix, Arizona, USA; Nov.
11-17, 2016 https://asmedigitalcollection.asme.org/IMECE/proceedings-abstract/IMECE2016/50527/V002T02A076/265260
Because:
- A sufficient preload force can only be applied in a process-reliable manner with yield point
controlled tightening.
- This creates a flow of forces in the coated joint.
- Possible sliding in the joint resulting in consequential damages and a failure of the
connection are prevented by the created frictional connection from the beginning.
- Many of the examined coating layers were undamaged.
Corrosion protection remains in place after tightening and loosening.
18.09.2020 30Possible tightening and analyzing methods with the Eco2TOUCH-Pump (1) torque controlled tightening (*indirect!) (2) torque controlled/angle monitored tightening (3) torque controlled/yield point monitored tightening (4) Torque & angle controlled tightening (5) preload controlled tightening (*indirect!) (6) yield point controlled tightening (7) yield point controlled, angle monitored tightening (8) external process control with pressure control with standard industry interface 0..10V / 0..20mA - sequencer (combination of tightening programs) - torque analysis tool *standard version, can be expanded 18.09.2020 31
And, as a “goody”, process-reliable tightening documented in text and graphics with integrated tightening process evaluation without reaction arm - safe - protecting the equipment - with a constant friction value - no spinning of bolts 18.09.2020 32
Application of no-rotation, hardened washers for safe tightening while protecting the equipment without reaction arm or back-up wrench 18.09.2020 33
36 Volt Battery-Tools - Lithium-Series II (LST)
The digital, battery-operated torque / angle Torque-Wrenches from 200 Nm to 6,799 Nm
The first battery-wrench series with TorcSense™
Technology
That means, this battery-wrench series has:
a measured control factor
(e.g. torque )
and
a measured monitoring factor
(e.g. angle)
The LST transducer independently measures strain which is interpreted as torque. The LST motor
independently measures angle.
18.09.2020 34Note: 4. Hamburger Verschraubungsforum
from 09. unti 10.12.2020 east-Hotel Hamburg
Organizer:
F. REYHER Nchfg. GmbH & Co. KG
Kempchen Dichtungstechnik GmbH
HYTORC – Barbarino & Kilp GmbH
Schrauben-Verschrauben-Dichtungen
Hamburg 09. bis 10. Dezember 2020
www.verschraubungsforum.de
The topics covered include:
"Determination of force influences with the help of micrometers on Example of wind turbines "
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37Herzlichen Dank für Ihre Aufmerksamkeit !!! Thank you for your attention !!! HYTORC-Barbarino & Kilp GmbH sowie devotec GmbH Justus-von-Liebig-Ring 17 D-82152 Krailling / Nähe München Patrick Junkers Tel: +49 – (0)89 – 23 09 99-30 Fax: +49 – (0)89 – 23 09 99-14 Mobil: +49 –(0)152 – 22 80 99 75 eMail: p.junkers@hytorc.de eMail: info@hytorc.de www.anziehverfahren.de www.hytorc.de www.vt-forum.de 18.09.2020 38
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