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Thin Wall Bolt

The Thin Wall Bolt, known as the TW Bolt, was developed as a blind fixing which could be used in conjunction with cladding material or lightweight steel sheet.

Thin Wall Fasteners

The TW Bolt combines convenience with performance. Once the bolt is fitted, only a low profile head is visible with no stud, while the bolt itself boasts a high shear capacity.

Advantages of the TW Bolt:

  • Quick and simple installation
  • No requirement for an oversized hole
  • Durability augmented by zinc electroplate finish
  • Makes any assembly more efficient

We’re constantly developing new products and devising innovative applications. Please visit our expert guides page to learn more.

For detailed information on installation or removal, please view our Thin Wall Bolt Installation and removal guide TW Fitting Instructions.

If you have a specific project in mind, please get in touch using the contact details below. Our team are ready and waiting to explain exactly how Blind Bolts could help.

Thin Wall Bolt

Thin Wall Bolt

Technical Data

Thin Wall Bolt Specifications

NOTE: All dimensions are in mm unless stated otherwise.

The Blind Bolt Company reserve the right to change these technical details without notice.

Thin Wall Bolt Product Specification
Zinc Nickel Technical Data

Bolt Size Hole Depth Clamping Range (mm)
(Stock Number) Diameter (mm) Clearance (mm) Min Max
TW5ZF-10 8 35 2 10
516" 1 38" 564" 1332"
TW5ZF-16 8 40 8 16
 516" 1 916" 516" 58"
TW6ZF-10 10 35 2 10
 716" 1 3⁄8" 564" 1332"
TW6ZF-16 10 40 8 16
 716" 1 916" 5⁄16" 5⁄8"
TW8ZF-10 13 35 8 16
 916" 1 34" 564" 1332"
TW8ZF-16 13 40 8 16
 916" 2" 5⁄16" 5⁄8"

Design Resistance for TW Type Blind Bolts
Zinc Nickel - In Accordance with AC 437 and AISC 360-10

TW Bolt Size Tension Resistance Shear Resistance
LRFD ASD LRFD ASD
kN KIPS kN KIPS kN KIPS kN KIPS
TW5 5.32 1.24 3.68 0.83 14.6 3.28 9.73 2.19
TW6 14.0 3.16 9.36 2.10 21.7 4.87 14.5 3.25
TW8 22.5 5.06 15.0 3.37 37.9 8.52 25.3 5.68

Design resistances in shear and tension are presented above. The resistance values may be compared directly with the ultimate loads applied to the fixing.
The bearing resistance may be calculated in accordance with the design standard, based on the external diameter of the collar, as given above.

Fixings subject to combined shear and tension should be verified in accordance with the design standard, using the design resistances presented above.

If tension is applied to a fixing in a relatively thin wall application, the deformation of the connected material should be considered at serviceability (working loads) and at the ultimate limit state, as deformation is likely to be the limiting feature of the connection.

Thin Wall Bolt Product Specification
Stainless Steel A2-70

Bolt Size Hole Depth Clamping Range (mm)
(Stock Number) Diameter (mm) Clearance (mm) Min Max
TW5SS-10 8 35 2 10
516" 1 38" 564" 1332"
TW5SS-16 8 40 8 16
 516" 1 916" 516" 58"
TW6SS-10 10 35 2 10
 716" 1 3⁄8" 564" 1332"
TW6SS-16 10 40 8 16
 716" 1 916" 5⁄16" 5⁄8"
TW8SS-10 13 35 8 16
 916" 1 34" 564" 1332"
TW8SS-16 13 40 8 16
 916" 2" 5⁄16" 5⁄8"

Design Resistance for TW Type Blind Bolts
Stainless Steel - In Accordance with AC 437 and AISC DESIGN GUIDE 27

TW Bolt Size Tension Resistance Shear Resistance
LRFD ASD LRFD ASD
kN KIPS kN KIPS kN KIPS kN KIPS
TW5 6.15 1.38 4.1 0.92 12.5 2.82 8.36 1.88
TW6 10.5 2.36 7.0 1.57 18.7 4.21 12.5 2.80
TW8 18.2 4.08 12.1 2.72 32.6 7.34 21.8 4.89

Design resistances in shear and tension are presented above. The resistance values may be compared directly with the ultimate loads applied to the fixing.
The bearing resistance may be calculated in accordance with the design standard, based on the external diameter of the collar, as given above.

Fixings subject to combined shear and tension should be verified in accordance with the design standard, using the design resistances presented above.

If tension is applied to a fixing in a relatively thin wall application, the deformation of the connected material should be considered at serviceability (working loads) and at the ultimate limit state, as deformation is likely to be the limiting feature of the connection.

Thin Wall Bolt

Fixing Data Explained

Thin Wall Bolt testing data explained - thin wall bolt technical data

The unique and innovative design of the TW Bolt means that certain specific criteria need to be met in order for it to be applied successfully.

Using these criteria means being aware of the way in which the dimensions of each thin wall bolt are measured from the testing data, and these details are set out below.

The image above also offers a pictorial representation of each term.

If you still have any questions about the testing data, please get in touch with us using the contact details at the bottom of the page or by sending us an email by clicking here.

What Is Minimum Fixing Thickness

The minimum fixing thickness is the figure applied to the minimum distance which each bolt is able to fix.

The overall thickness of the materials being clamped is the figure used to make this calculation.

What Is Maximum Fixing Thickness

The maximum fixing thickness is the figure applied to the maximum distance that each bolt is able to clamp.

The overall thickness of the materials being clamped is the figure used to make this calculation.

It should be noted, however, that the maximum fixing thickness of a standard bolt can be extended to a large degree through the use of extension sleeves.

Please contact us for more specific information on this point.

What Is Tensile Strength

The tensile strength of a TW Bolt is the pull-out force needed for the bolt to fail when a tensile load is acting upon it.

What Is Depth Clearance

The depth clearance refers to the minimum space required within a cavity wall for the legs on the TW Bolt to deploy effectively.

The measurement has to be noted with great care when fixing into Steel Hollow Sections in order to make sure that the bolt doesn’t reach as far as the opposite section wall before being correctly installed.

Thin Wall Bolt

Fitting Instructions
Installations & Removal Videos

The following videos visually represents the detailed installation of the Thin Wall Bolt.

Fitting Instructions Video Blind Bolt