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The Nord-Lock Group
PIONEERING SAFETY
Petter Viken
Business Developer – Oil & Gas
The automotive industry showed that
23% of car problems relate to loose bolts
and 12% of all new cars have loose
bolts.*
Every 3rd week an incident due to failed
bolted joints occur on an offshore
installation on the Norwegien continental
shelf.**
*boltescience.com **oljefakta.no
Nuts and bolts are the world’s most common machine
elements and therefore the most common cause for
applications to…
• Fail
• Require maintenance
• Cause down-time
• Require corrective actions
… and thereby cause significant additional costs
Our mission is to safeguard your investments.
Our vision is to be your trusted global partner
in optimization of bolted connections.
Multifunctional wedge-locking
Wedge-locking solutions
Multi-jackbolt tensioners
Expansion bolting
Multifunctional Wedge-locking
Wedge-locking solutions
Multi-jackbolt tensioners
Expansion bolting
Wedge-locking
solutions
Washers Wheel nuts
Combi bolts Customer
specials
m
Critical displacement threshold :
d = m . F0 . Lp
3
12 . Eb . I
Slipping force in the interface Fslipping = m . F0
Spontaneous bolt loosening (rotation of fastener)
d = 4 µm
Critical displacement threshold :
d = m . F0 . Lp
3
12 . Eb . I
Slipping force in the interface
Fslipping = µ . F0
Numerical
application
Fslipping = 4500 N
d = 0,15 . 30000 . 103
12. 210000 . 64
. 104
Example:
M10 bolt
Preload : F0 = 30 000 N
Under head friction coefficient : µ = 0,15
Clamped thickness : Lp = 10 mm
Spontaneous bolt loosening (rotation of fastener)
The principle
Installation
Verify a safe locking
1. Tighten joint
2. Make a mark
3. Untighten slowly
4. Sliding between
cam faces
5. Impression marks
Washer type Code
Steel washer EN 1.7182 / 1.7225 flZn General steel app.
Stainless steel EN 1.4404 / AISI 316L SS General stainless steel app.
Stainless steel SMO 254® 254 Salt water / Chlorides
Stainless steel Hastelloy® C-276 276 Acids
Stainless steel Inconel® 718 718 High temp / Cryogenic
Nord-Lockk
Control number-
Code-
Washers with increased outer diameter (SP)
Slotted holes
Flanged fasteners
Low strength materials (eg aluminium)
Coated / painted surfaces
Visual requirements
Performance Services
Bolted joint designed
with Life Cycle
Profitability mind set
Bolted joint designed
with component cost
mind set
Cost savings
Manufacturer of industrial components
Assemblies in numbers
Problem
Tightening aspect
Solution
Result
Investment cost
Reduction of tightenings
Fastener optimization (M10 M8)
Savings (per year)
ROI (1 year)
Not considered in calculation:
68 fastening points
60 units manufactured a week
Slackening and self-loosening.
Long tightening sequence:
- Snug tightening
- Final tightening
- Re-tightening on site before installation
68 bolts x 3 tightenings x 60 units x 50 weeks =
612 000 tightenings per year
- Nord-Lock redesigns the joint to a smaller diameter bolt
- Spec in Nord-Lock X-series washer
1 tightening per joint
EUR 47 229
EUR 122 400 / year (EUR 0,3 x 408 000 tightenings)
EUR 31 824
EUR 106 995
2,3
Time aspect: 4 hours of settlement time x 60 units x 52 weeks = 12480 unnecessary
production hours.
Return of
Investment
Case study
Transocean / AKER Solutions Nord-Lock washers
Tightening torque / sequence
Assembly instructions
No separation of clamped parts
No movement between clamped parts
No exceeding of the yield limit
Design within the fatigue limit
Sufficient corrosion resistance
Safe bolt securing device
Accurate tightening
Simplicity – Project on time
Materials
CE
EN 14399
ETA EN 1090
Eurocode
Eurocodes- a set of
harmonized technical rules
Eurocode 1
Eurocode 2
Eurocode 3
Eurocode 4
Eurocode 5
Eurocode 6
Eurocode 7
Eurocode 8
Eurocode 9
- Design of steel structures
- Mandatory since 2013-01-01
Eurocode 3
EN 1993
Steel structure is poorly described in EC3
• permanent structural steel members designed to
carry load
Utilize EN 1090-2
• to provide the requirements for a steel structure
Stipulate that a shear joint should be preloaded /
utilize bolt locking when subjected to:
• Impact
• Vibration
• Load reversal
A non-preloaded joint is a joint that does not require
preload and is tightened in a uncontrolled way. In
reality, some preload always exist.
Joint type (Shear) Loading Bolt grade
A) Bearing type Non-preloaded 4.6 – 10.9
(ISO 4014/16/17/18)
(EN 14399)
B) Slip resistant -
service
Preloaded 8.8-10.9
(EN 14399)
C) Slip resistant -
ultimate
Preloaded 8.8-10.9
(EN14399)
Joint type
(Tension)
Loading Bolt grade
D) Non-preloaded
Non-preloaded
4.6 – 10.9
(ISO 4014/16/17/18)
(EN 14399)
E) Preloaded Preloaded
8.8-10.9
(EN14399)
EN 14399
- Structural fasteners
EN 14399- 1 / -10
High strength structural bolting assemblies for steel
structures
HR grade 8.8 / HV grade 10.9
Normally supplied in CE-marked sets comprised of:
• Bolt
• Nut
• 2 washers
• K-factor
EN 14399 fasteners cover all joint types (A, B, C, D, E)
EN 1090
EN 1090-1
EN 1090-2
EN 1090-3
- Technical requirements for steel
structures
- Refers back to Eurocodes
- Allows bolts as:
• EN 14399 for pre / non-loaded joints
• EN 15048-1 for non-preloaded joints
(CE-marked ISO fasteners)
EN 90 CE
Since 1993
Conformiteé Européenne
Means that a product conforms to EU-directives
A product can be sold within EES (includes
Norway)
25 product categories can be CE marked, fasteners
are not included as they are ISO and not EN
standardized
In this case bolts, nuts, washers are considered
building material and have a EN norm and CE
marking can be applied.
EN 14399 and EN 15048-1
ETA
Nord-Lock has created a wedge-locking washer for
EN 14399 fasteners
ETA – European Technical Approval
DIBt has issued an ETA for Nord-Lock so called ”SC”
washers to be used with EN 14399 and still comply
with Eurocode 3, EN 1090
DIBt – Deutsches Institute für Bautechnik
Multifunctional Wedge-locking
Wedge-locking solutions
Multi-jackbolt tensioners
Expansion bolting
Bolt-style
tensioners
Nut-style
tensioners
Pre-designed
& specials
Flexnuts
Multi-jackbolt
tensioners (MJTs)
Principle of MJT
Distribute the total
torque over several
jack bolts
Tension the the main
thread
MJT – Multi Jackbolt Tensioner
Cylindrical nut body Strong and compact design
Transfers the preload to the main
thread
Jackbolts Low tightening torque
High elasticity
Accurate friction conditions
Hardened Washer Protects the contact surface
Torque tightening
No friction on the main stud Reuse of the studs
Maximization of possible axial load
(possible to use smaller bolts)
No fretting or seizure
Low torque Low cost hand tools
High precision in tightening = 1,2 (+/- 10% in obtained preload)
Precise assembly
Cost saving in construction
Optimization is possible
Example: M64x6 grade 8.8 at 1270 kN → 13 000 Nm
Superbolt → 315 Nm
Tightening benefits of MJT
Since no rotation occurs
between the main threads and
contact surface during
tightening:
Galling and seizure of threads
and fretting of bearing surface
is avoided
Fasteners can be
disassembled without being
damaged
Reuse of expensive fasteners
possible
Tightening benefits of MJT
Why is tightening so precise?
Very accurate friction conditions
under the jackbolts and in the
jackbolt threads (MoS2 or Graphite)
Very small friction radius
rf
When tightened Nuts style MJT flex
Jackbolts compress (instead of
tension as with regular bolts)
The additional elasticity of a
SUPERBOLT = Prolongation
of the clamping length of 2-3
times the nominal bolt
diameter
Elastic behavior of MJT
Benefits of incline compensation
Hexagonal nut, Cylindrical hydraulic nut Bending moment in stud
Stress concentrations
Point contact
Stress corrosion
Risk of cracking
Creep
Lift off
No reuse of stud
High risk of failure
Superbolt Pure tension in stud
Full contact on bearing surface
No cracking
No creep
No stress corrosion
No lift off
Reuse of stud
Safe joint
Load distribution in MJT threads
Hexagonal nut
Cylindrical hydraulic nut Superbolt
Thread
Load
Thread Load
Tightening of MJT
3
7
1
2
4 3
1
2
4 3
50%
100%
100%
(20°)
Cross-wise tightening pattern
Only hand tools required
No special skills required
Tightening routine is very familiar for most staff
1-3 mm
Untightening of MJT
Under no circumstances unload
single screws completely.
Apply penetraiting oil, especially
with any rust formation
Break loose each jackbolt in a
circular pattern
Then loosen until max. ¼ turn
www.nord-lock.com
HOW CAN WE ENHANCE
YOUR SAFETY?