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global fastening solutions

Manufacturing, engineering and integral logistics

TH preload system

Minimum guaranteed preload 75% of bolt yield stress

TSF has designed, developed and patented the TH preload system with the following objectives:

  • Provide bolted joints with high requirements in preload.
  • Provide bolted joints with high requirements in preload and untightening resistance.
  • Provide bolted joints with low requirements in preload and high untightening resistance.
  • Provide control of stress applied to bolted joints with soft components keeping high preload on bolt.

Advantages

  • Self-locking result.
  • Maintenance costs are drastically reduced.
  • Reduced number of fastening elements with respect to torque control (25-35% less).
  • It is suitable for use with standard pulling equipment.
  • Multiple reuse of the element.
  • Low dispersion (less than 5%).
  • High stability of the preload.
  • Low load distribution factor for the fastening element. Lowers the fatigue range.
  • Inflexible to bending moments.
  • Simultaneous assembly of fastening elements. Elimination of elastic interaction of close elements.
  • Benefits of elongation, without the disadvantages of friction.
  • Same protocol for all sizes.
  • It can be designed as standard parts or according to different designs adapted to any specific application from M12 up to M150.
  • Every specific union would be object of its own engineering analysis according to each customer application.

Our TH preload system is certified by Lloyds Register.

Image graphic

TH Standard

TH Standard image
TH Standard assembly over washer
TH Standard image
TH Standard assembly over flange
table image

**D2 : depends of the size puller bridge.

The dimensions shown on the tables may be modified, as every specific union would be object of this own engineering analysis.

nut image

TH Round

TH Round image
Rounded TH assembly over washer
TH Round image
Rounded TH assembly over flange
table image

**D2 : depends of the size puller bridge.

The dimensions shown on the tables may be modified, as every specific union would be object of this own engineering analysis.

nut image

Higher untightening resistance increasing the moment

Graphic M1 imgage
1 - Standard nut flat base
Graphic M2 imgage
2 - TH nut conical base

M2 > M1

Section AA Image
Comparison of standard nut and TH with the same preload

Higher untightening resistance due to higher preload values

Nuts image
Graphic image
Pressure cone
Graphic image
Pressure cone
Graphic image
Decomposition of preload reaction in normal and axial stresses at washer
Graphic image
Decomposition of preload in normal and axial stresses at stud thread
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