Content with preload

03 May 2022
The clamp length is the distance between the bolt head and the nut holding all the components together. It includes steelwork, any shims, plates and washers used. The grip length is the thickness of the steelwork (thats includes plates, shims etc.) that can be gripped together by the bolt and nut assembly. It strictly depends on the specific application (how many washers are used in the assembly). Example For EN 14399-3 hexagon bolt assembly type HR , diameter M30 and 100mm in length, the reference clamp length will be between 48mm up to 69mm, whereas the grip length with one washer will be 44-63mm and two washers 40-57mm.
Read more about What is the difference between Clamp length and Grip length in EN 14399 assemblies?

04 February 2022
Apart from dimensional differences ( bigger head of the bolts and bigger nuts on preloaded assemblies), the main difference is in the way how these goods are installed. Non-preloaded bolting assemblies are generally tightened to at least snug-tight. The connected components are drawn together to achieve firm contact without any specific preload. The “snug-tight” is generally referenced as tightening the assembly by one man using a normal-sized spanner without an extension arm until the wrench starts hammering.
Read more about What is the difference between preloaded and non-preloaded bolting assemblies?

02 March 2021
When ordering Preloaded Assemblies (EN 14399-1) to be installed with Direct Tension Indicator Washers (DTI’s) , there are 4 different methods of how they can be installed. Depending on the access or preference, you may choose one method, over another. At the purchase stage, we may not know how you will be installing your assemblies. Please read below, as you may require an additional washer(s) to be purchased. Figure 1 Figure 2 Figure 3 Figure 4 Installation methods: Installing DTI under the bolt head when the nut is rotated (Figure 1)
Read more about Do I need Bolt Face Washer or Nut Face Washer (EN 14399-9) with DTI's?

29 January 2016
Due to the compression ability of paint, galvanising coating and other types of surface protection , it is required that places of joints are cleaned from any coating before installation. After the installation process, depending on the type of coating of the assemblies, the whole surface can be further covered to restore corrosion protection in joint places.
Read more about Can Preload bolt assemblies (HSFG) be used on painted or galvanised surfaces?

18 December 2015
An overall recommendation is to have a minimum of 1 (one) thread above the unloaded face of the nut, and a minimum of 4 (four) threads before shank of the bolt and the nut.
Read more about Are two threads protruding through a preload fastener enough?

18 December 2015
Due to safety reasons and according to BS 4604-1 (Withdrawn): “If after final tightening a bolt or nut is slackened off for any reason, the bolt, nut and washer shall be discarded and not re-used.” In accordance with the latest EN 14399 If the assembly has been tightened to the minimum force - 70%, the assembly cannot be re-used. Andrews Fasteners recommend, once assembly has been preloaded, in any form and need to be de-assembled, to discard it and replace with fresh assembly (and relevant components like DTI washers) due to wearing off applied lubrication which may invalidate torque figures supplied for installation (k-Class K1 or K2) or cause difficulty to compress DTI washers at the right level (k-Class K0).
Read more about Can Preload (HSFG) assemblies be de-assembled once they have been assembled?

18 December 2015
To accommodate the thickness of zinc it is normal practice to over-tap the nut thread. This operation reduces the strength of the nut and the overall strength of the nut and bolt assembly. To improve the strength of the assembly manufacturers use either a thicker nut (increasing the number of threads between the nut and the bolt in the assembly) or a higher grade nut. BS EN 15048-1: To achieve full tensile resistance, hot-dip galvanized assemblies can require special measures, see EN ISO 10684, Annex F.
Read more about Should higher grade nuts be specified for use with galvanized or sherardized set screws and bolts on CE (UKCA) approved assemblies?

18 December 2015
HR (British/French) bolt The British/French approach following BS EN 14399-3 and BS 4395 is to use thick nuts and long thread lengths in the bolt assembly to obtain ductility predominantly by plastic elongation of the bolt. The longer thread length is necessary to ensure that the induced strain is not localised. These bolts are relatively insensitive to overtightening during preloading although suite control is still important. Furthermore if severely over-tightened during preloading the ductile failure mode of the bolt assembly is predominantly by bolt breakage, which is readily detectable.
Read more about What is the difference between HR and HV bolt assemblies?

18 December 2015
According to standard requirements, during assembly, you should not use any additional lubrication apart from that originally supplied. BS EN 14399 standard is leaving a clause, that additional lubrication should be used if it is subject to supplier recommendation. Andrews Fasteners BS EN 14399 Assemblies are supplied to k-Class k0 and are offered pre-lubricated. We are supplying lubricated parts of the assembly. Lubricated parts are used where due to surface coating , maximum tension needs to be controlled to prevent seizure.
Read more about Should preloaded assemblies be assembled with lubrication?

28 October 2015
Our production factory, AndFast Malaysia between 19-22 October 2015 went through Certification Renewal by the accredited body Lloyd’s Register Quality Assurance ( LRQA ). New Approval On that occasion, AndFast Malaysia went through a Change of Approval to include preloaded HR Countersunk CE Assemblies as per EN 14399-7 and Washers as per EN 14399-9. LRQA successfully verified all the requirements and issued a final report for further approval for our factory.
Read more about AndFast Malaysia Certificate Renewal and Change of Approval