2.0 MODULAR SUPPORT TECHNOLOGY
Modular Support Systems Technical Guide , Edition 1
2.3 INFORMATION ON ADJUSTABILITY OF MT COMPONENTS
The MT System , as with all Hilti modular installation systems , is designed for a single permanent installation . A single permanent installation is achieved with the following : the assembly process is complete , the system is subjected to the final in-use conditions , and the expected design loads are applied to the structure . It may remain in this use for as long as the expected lifespan , with due adherence to projectspecific inspection and maintenance requirements . It is not designed to be completely disassembled and then rebuilt or re-purposed , as the use conditions of the original structure may have changed over time ( e . g . applied loads , impact , corrosion attack , product modifications etc .). Any reuse of the MT System beyond a single permanent installation is at the risk of the customer .
Twist-Lock ( MT-TL ) Connection Mechanism
Thread Forming Bolt ( MT-TFB ) Connection Mechanism
The MT-TFB forms a thread into the reinforced hole of the MT girder during assembly . After assembly , the MT-TFB may be subsequently removed to enable positional adjustments of connectors . Once this thread has been formed , so long as the thread remains intact ( e . g . it is not cross threaded ), the threaded hole can be used up to four additional times ( five in total ). A torque-controlled wrench is recommended when reusing a reinforced MT girder hole . Reuse of the MT-TFB is possible but should be limited to five re-uses . Any reuse beyond this limit could lead to degradation of the tip of the bolt , thereby negatively impacting its performance .
If a customer is uncertain how many times a reinforced hole in an MT girder has been used , then a fresh hole should be used for installation . Likewise , a new MT-TFB should be used if it is unknown the number of times it has been used previously .
The Twist-Lock interface is designed for a single permanent installation . However , during assembly , the Twist-Lock may be repositioned as necessary until final installation is completed . Final installation is achieved when the Twist-Lock installation torque in the Instructions For Use ( IFU ) is reached .
Repositioning the Twist-Lock can occur at any point along the MT channel length . Once the installation torque as defined in the IFU has been applied to the Twist-Lock , its location can no longer be adjusted . A new Twist-Lock must be utilized for final installation in a new location .
The upper limit of five uses for a single MT-TFB for MT girder connections may be extended if the Hilti Adaptive Torque Module ( SI-AT-A22 , in combination with the Hilti impact wrench SIW 6AT-A22 ) is used with the correct MT-TFB parameter set ( found via the QR code on the box of the MT-TFB ’ s ). An important feature of the Adaptive Torque Module is that it will indicate if the connection mechanism has been correctly set . If it determines the connection mechanism has been correctly set , a green light will illuminate , indicating the correct amount of pre-tensioning has been achieved . If a red light illuminates , then the connection mechanism is not sufficient and should not be used . Refer to the product documentation for the Adaptive Torque Module for additional guidance .
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