---
title: "What Are Structural Blind Bolts Used For?"
description: "Structural Blind Bolts (Trade series (structural blind bolts)) are used for structural and machine joints that must be tightened to a controlled preload."
url: https://engineeringhardware.com/applications/structural-blind-bolts/
source: Engineering Hardware & Fasteners
---

# What Are Structural Blind Bolts Used For?

Bolts · Trade series (structural blind bolts) · Application guide

Typical applications, the industries that specify structural blind bolts, and how to choose the right size, material and finish for the joint.

Structural Blind Bolts are used for structural and machine joints that must be tightened to a controlled preload. They are manufactured to Trade series (structural blind bolts), and the choice of size, property class and finish is driven by the load in the joint and the environment it sits in.

- **Primary duty:** Structural and machine joints that must be tightened to a controlled preload
- **Governing standard:** Trade series (structural blind bolts)
- **Category:** Bolts

Application notes are general engineering guidance. Verify the property class and any approval requirement against your own design calculation.

![What Are Structural Blind Bolts Used For? application image](https://engineeringhardware.com/wp-content/uploads/2026/09/Structural-Blind-Bolts.webp)

Structural Blind Bolts are selected when an assembly calls for structural and machine joints that must be tightened to a controlled preload. This application guide to the Trade series (structural blind bolts) type covers concrete end-uses, the specification checklist, correct installation, and where an alternative fastener performs better.

## Typical Applications for Structural Blind Bolts

The most common settings where these are specified:

- **Structural steel:** bolting beams, base plates and bracing where a defined preload and property class are required.
- **Automotive & transport:** chassis, suspension and powertrain mounting points subject to vibration.
- **Heavy machinery:** securing gearboxes, frames and guarding on plant that sees shock loads.
- **Energy & infrastructure:** tower, pylon and pipework supports exposed to weather and long service life.
- **General machine building:** fastening covers, brackets, motors and sub-assemblies on production equipment.

Product catalog

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## How to Specify Structural Blind Bolts for Your Application

- **Size:** Match the size to the mating part — see the dimension table below for each option.
- **Strength class:** Choose the property class (e.g. 8.8, 10.9, 12.9 or A2/A4 stainless) for the load and environment, and tighten to the matching torque so the joint relies on preload, not friction.
- **Environment:** For damp, coastal or chemical exposure prefer A4/316 stainless or a suitable coating; indoors, plated steel or A2 is usually sufficient.
- **Standard:** This product is supplied to Trade series (structural blind bolts). Quoting the standard on your order guarantees interchangeable dimensions between suppliers.

## Installation & Assembly Practice

- Tighten to the torque for the size and property class with a calibrated wrench — the joint is held by preload, not by the thread friction alone.
- Ensure at least one full thread projects beyond the nut after tightening, and never re-use a bolt that has been tightened into yield.
- Under slotted or oversized holes, fit a hardened washer so the preload does not relax into the hole edge.

## Common Selection Mistakes with Structural Blind Bolts

- Specifying class 12.9 "to be safe" in a corrosive environment — high classes are more sensitive to hydrogen embrittlement and stress corrosion; 8.8 hot-dip galvanized often outlasts them outdoors.
- Choosing a length that puts the shear plane through the threaded portion when a plain shank (partially threaded bolt) was available.
- Mixing stainless bolts with plated-steel nuts: the joint loses its corrosion logic and can gall or seize.

## Where Structural Blind Bolts Are Not the Right Choice

Not for permanent joints that will never be opened (a rivet or weld is cheaper), and not where the head must sit flush — use a countersunk screw instead.

Custom manufacturing · Made to drawing

## Need a structural blind bolts outside the standard range?

Lengths and thread lengths outside the standard table are the commonest request, followed by a drive the standard does not offer and a head marked with your own part number. Made by cold heading or hot forging.

Minimum order from 2,000 pieces; samples within 7 days of drawing approval.

[Custom bolt manufacturing](https://engineeringhardware.com/custom/bolts/)[Send a drawing](https://engineeringhardware.com/custom/bolts/#rfq)

## Technical Drawing

Dimensioned line drawing of mechanically locked, retained Structural Blind Bolts to Trade series (structural blind bolts). Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected.

- **Rated for:** structural shear and tension
- **Access:** one side only
- **Distinguished from:** an ordinary blind rivet, whose stem is not retained

## Dimensions & Specifications (Trade series (structural blind bolts))

| Stem | Rated for | Access | Distinguished from |
| --- | --- | --- | --- |
| mechanically locked, retained | structural shear and tension | one side only | an ordinary blind rivet, whose stem is not retained |
| mechanically locked, retained, countersunk | structural shear and tension | one side only | an ordinary blind rivet, whose stem is not retained |

Inside the plant

## Manufactured in our own plant

This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided.

1. ![Wire rod feeding into a cold heading machine](https://engineeringhardware.com/wp-content/uploads/2026/08/09-wire-rod-feed-cold-heading-machine.webp) 01 **Cold heading** Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail. Head dimensions and under-head radius checked at set-up and per shift.
2. ![Thread rolling machine producing bolt threads](https://engineeringhardware.com/wp-content/uploads/2026/08/03-thread-rolling-machine-bolt-production.webp) 02 **Thread rolling** Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch. Go / no-go ring gauges to ISO 965 tolerance class 6g.
3. ![Baskets of bolts staged for heat treatment](https://engineeringhardware.com/wp-content/uploads/2026/08/05-heat-treatment-baskets-black-bolts.webp) 03 **Heat treatment** Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it. Core hardness and tensile tested per lot to ISO 898-1.
4. ![Zinc plated bolts in a treatment basket](https://engineeringhardware.com/wp-content/uploads/2026/08/23-zinc-plated-bolts-treatment-basket.webp) 04 **Surface treatment** Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list. Coating thickness and neutral salt spray hours to ISO 9227.

## Frequently Asked Questions

### How do I choose the right size of Structural Blind Bolts?

Match the size to the mating part using the dimension table on this page.

### How tight should Structural Blind Bolts be torqued?

Tighten to the torque for the size and property class so the joint is held by bolt preload. The size pages and torque reference table give recommended values; use a calibrated torque wrench for anything structural.

### What material should Structural Blind Bolts be for outdoor use?

For damp, coastal or chemical environments specify A4 (316) stainless or a suitably coated steel. For indoor or dry use, A2 (304) stainless or zinc-plated steel is normally adequate.

### Are Structural Blind Bolts made to a recognized standard?

Yes — they are manufactured to Trade series (structural blind bolts), so dimensions are interchangeable between suppliers when you quote the standard on your order.

### Can I get a quote for Structural Blind Bolts in the size and material I need?

Yes. Use the technical drawing and quote form on this page to set the size and options, then send the exact configuration to our team for pricing and lead time.

## Related Pages

Product page: [Structural Blind Bolts — specifications & sizes](https://engineeringhardware.com/fastener/structural-blind-bolts/)

### Structural Blind Bolts Specification Guides

### Related Fastener Applications