Content with Pre-load

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.
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?

12 January 2016
The minimum thread length is calculated strictly according to EN 14399-3 for preload bolts - System HR and EN 14399-7 for preload countersunk head bolts - System HR. In calculation, you need to consider standard reference thread length (b), minimum length of the shank - un-threaded part of the bolt, and distance from the head of the bolt till first full thread. To help with that, we have created two useful calculators:
Read more about What is the minimum thread length on preload bolts?

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Due to safety reasons and according to BS 4604-1 (Withdrawn): “If after final tightening a bolt or nut is slackened off for any reason, the bolt, nut and washer shall be discarded and not re-used."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 should stand for High Resistance and HV for Hochfeste Bolzen mit Vorspannung (in English is high resistance bolts for pretension). The second is an official description, and they should serve the same purpose. See also: What is the difference between HR and HV bolt assemblies?
Read more about What does the HR & HV symbols mean?

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?

01 February 2015
Direct Tension Indicators Washers (BS EN 14399-9) Andrews Fasteners company in manufacturing Direct Tension Indicators Washers (DTI Washers) in well know in construction industry company based in United States – TurnaSure . All our washers are marked with our headmark FAST (previously AND.). Benefits of using Direct Tensions Indicators Washers: The use of DTIs is the simplest way of ensuring that bolting assemblies are tensioned properly; The use of DTIs saves cost on inspection ; No torque figures are required, only feeler gauges; Risk reduction on over tightening; DTIs are manufactured in compliance with EN 14399-9 and can be supplied with CE approved preload bolting assemblies; Unique curved protrusion design of Turnasure DTIs reduce necessary of using nut face / bolt face washers for 8.
Read more about Direct Tension Indicators Washers (BS EN 14399-9)