Tightening of TCBs

 

Tightening of TCBs

Before graduation of preloading, the related components shall be fitted collectively and the bolting assemblies shall be brought to a snug tight circumstance. This tightening technique shall be executed from bolt to bolt of the group starting from the maximum inflexible part of the relationship and transferring regularly closer to the least rigid element (touch to non-touch surfaces). In order to make certain that the preload in absolutely established bolting assemblies meets the specified minimal preload requirement, the installation process includes two tightening levels. The first degree applies a bedding torque to the bolts to make sure a firm contact among components. Pre-tensioning (stage 1) may be performed by way of:

i. The use of the shear wrench but simplest snugging assemblies and not shearing off the splines. When the usage of this method the operator will observe a distinct trade within the sound/tone of the wrench motor. This indicates that pre-tensioning has started as the bedding torque is being applied. If pre-tensioning has came about, then while the strength cause is disengaged the wrench gearing will go into reverse and opposite allowing the device to be easily removed from that specific bolt. This whole system may be felt by using the operator.

Or

ii. The use of a preferred nut runner/effect wrench with a deep socket to tug all surfaces into touch with out related to the bolt spline;

NOTE – If mating surfaces are extensively distorted or misaligned then ‘slave’ bolts ought to be used.

 TC Bolts may be used as slave bolts however they ought to be clearly marked after which changed previous to final of entirety of the joint.

The 2nd tightening degree can handiest be finished the use of a shear wrench. When the spline stop of the bolt shears off on the smash neck, full preload has been caused.

If the bolting meeting cannot be mounted using shear wrenches, tightening shall be achieved in a conventional manner via

i. The use of the torque approach with the aid of the ok-magnificence K2 information (K2 values can be furnished upon request).

Or

ii. The use of an immediate tension indicator.

Inspection

Five bolt assemblies per prolonged lot are systematically tested in accordance with European standards. Axial hundreds are recorded onto the Certificates of Inspection TCB assemblies being delivered to site or works.

After the spline of bolt has sheared, the meeting preload ought to be identical to or greater than those values as required by the specification (see desk 1).

Since the fine warranty and integrity of the bolted connection is determined by using the bolting assembly itself, visual inspection of the bolt spline elimination is sufficient.

EN 1090-2:2018

Five Tightening of preloaded bolting assemblies

eight.Five.1 General

Unless in any other case distinct, nominal minimum preloading force Fp,C will be taken as:

Fp,C = zero,7 fubAs in which fub is the final strength of the bolt fabric and As is the stress vicinity of the bolt as defined in EN1993-1-8. This level of preload shall be used for all slip resistant preloaded connections and for all the different preloaded assemblies unless a decrease level of preloaded is detailed.