How do you tighten a HSFG bolt?
First Stage of Tightening: As a first stage, all bolts in the joint shall be tightened to ‘snug tight’ condition. Snug tight condition means the nut is tightened using an ordinary wrench by an average worker, applying maximum force on the wrench. This stage is required to bring the plies in close contact.
What is a load indicating washer?
Sometimes called load indicator washers or DTI washers, ASTM F959 washers are used to help determine when a structural bolt connection is installed to the correct tension. Traditional DTI washers employ a feeler gauge to measure the compression of raised nibs on the washer as the nut is tightened.
What is a PLI washer?
Preload indicating (PLI) washers are said to provide accurate measuring of the clamp force in a bolted joint, and work with joints that are inaccessible to torque wrenches. Washer types include standard for use under the nut, under the head for small spaces, and oversize for use with reworked joints.
What is turn of the nut method?
The Turn-of-Nut method is widely used to obtain the minimum preload tension force specified for bolts in slip-critical connections. This method consists in first snug-tightening the bolts.
What is difference between HSFG and normal bolts?
Where a traditional bolt will stop the plates in a connection from moving apart by supporting the weight on the bolt shank in the form of shear stress, an HSFG supports the weight by clamping the plates so tightly together that they can’t slip past each other.
What is an HSFG bolt?
HSFG bolts are high strength structural bolts which have been tightened such as to induce predefined tension in the bolt shank. Due to the tension in the bolt, the interface between the plies (steel members in a joint) cannot move relative to each other because of the frictional resistance.
How does a load indicator washer work?
DTIs are Direct Tension Indicators with a flexible silicone embedded in the depressions under the bumps. As the bumps in the steel DTI washer are compressed by the action of tightening the bolt, the silicone is squirted out and becomes a visible indicator of correct bolt tension.
What is torque turn method?
The torque-turn method is used when precise control over clamping force is required. The initial torque is required to bring all parts of the joint into contact. The additional turn provides the desired clamping force. Ensure that all fasteners have been torqued before you perform the additional turns.
What are HSFG bolts used for?
The HSFG bolts are used primarily in construction, Engineering, and structural steelwork. They cater to a variety of industries such as defense, petrochemicals, railways, and mechanical.
What grade are HSFG bolts?
M16 – Self Colour – HSFG – Bolt,Nut & Washers – 8.8 Grade – EN14399. High Strength Friction Grip Bolts (HSFG) bolts are high strength structural bolts that can been tightened to induce tension in the bolt shank.
Can a turnasure DTI be installed under a nut?
Otherwise ALL methods are good depending on the erector’s preference. TurnaSure curved protrusion DTIs can be installed under the nut WITHOUT the need or cost of a hardened washer. Assembling the DTI directly under the nut is satisfactory on standard length bolts in the usual two or three ply connections when hardened DH or 2H nuts are used.
When to use turnasure direct tension indicator ( DTI )?
ASTM F2437/F2437M for Carbon and Alloy Steel Compressible-Washer-Type Direct Tension Indicators for Use with Cap Screws, Bolts, Anchors, and Studs. TurnaSure’s DTIs are also manufactured for use on HV bolting assemblies per DASt-Guideline 021 and Japanese Standard JISB 1186-F10T strength strength structural bolting assemblies.
How does a DTI work on an anchor?
As the nut is turned to stretch the anchor bolt, the gap of the DTI is reduced proportionally to the tension being induced in the anchor. One of our most commonly used DTI designs has been specially made so that once the DTI is completely flat, the desired level of tension or clamping force is reliably present in the anchor bolt, stud, or rod.
Where do you put the DTI on a cap?
Most often, the DTI (or TIW) is placed under the head of a matching Grade 5 or Grade 8 (or Class 8.8 or 10.9) cap screw. The nut is turned to tighten the cap screw, and the resulting clamping force begins to flatten the protrusions. Other acceptable methods are shown below, including tightening into a tapped hole.