--- title: "What Are Large-Diameter Lockbolt Assemblies (BS 7805-2) Used For?" description: "Large-Diameter Lockbolt Assemblies (BS 7805-2) (BS 7805 Part 2:1997) are used for large-diameter swaged lockbolt joints in thick structural sections." url: https://engineeringhardware.com/applications/large-diameter-lockbolt-assemblies-bs-7805-2/ source: Engineering Hardware & Fasteners --- # What Are Large-Diameter Lockbolt Assemblies (BS 7805-2) Used For? Rivets · BS 7805 Part 2:1997 · Application guide Typical applications, the industries that specify large-diameter lockbolt assemblies (bs 7805-2), and how to choose the right size, material and finish for the joint. Large-Diameter Lockbolt Assemblies (BS 7805-2) are used for large-diameter swaged lockbolt joints in thick structural sections. They are manufactured to BS 7805 Part 2:1997, and selection is driven by the nominal diameter, the fit and tolerance the assembly requires, and the service environment. - **Primary duty:** Large-diameter swaged lockbolt joints in thick structural sections - **Governing standard:** BS 7805 Part 2:1997 - **Nominal diameter range:** 12.7 mm to 34.9 mm - **Category:** Rivets Application notes are general engineering guidance. Verify the property class and any approval requirement against your own design calculation. ![What Are Large-Diameter Lockbolt Assemblies (BS 7805-2) Used For? application image](https://engineeringhardware.com/wp-content/uploads/2026/09/Huck-C50L-Large-Diameter-Lockbolt-Assembly.webp) Large-Diameter Lockbolt Assemblies (BS 7805-2) are used primarily for large-diameter swaged lockbolt joints in thick structural sections. This page lists the industries and assemblies where they are specified, the selection criteria that matter for each application, installation practice, and the cases where a different fastener type is the correct choice. Parts are supplied to BS 7805 Part 2:1997. Stocked across roughly 12.7 mm to 34.9 mm, they cover heavy and structural work. ## Typical Applications for Large-Diameter Lockbolt Assemblies (BS 7805-2) The most common settings where these are specified: - **Heavy truck frames:** large-diameter structural joints in rails and crossmembers. - **Earthmoving equipment:** bucket, boom and chassis structures subject to shock. - **Rail vehicles:** high-cycle structures that need a permanent mechanical lock. - **Steel plant fabrication:** thick-section one-side joints using large pin and collar combinations. 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This product spans 12.7 mm–34.9 mm; check the full table below for the exact dimensions of each size. - **Material:** Choose the material and finish for the service environment — plated steel for general use, stainless for corrosion resistance. - **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 BS 7805 Part 2:1997. Quoting the standard on your order guarantees interchangeable dimensions between suppliers. ## Installation & Assembly Practice - Drill the hole 0.1 mm over the nominal rivet diameter and deburr both sides before setting. - Grip range must match the total joint thickness — a rivet set outside its grip range clamps poorly and works loose. ## Common Selection Mistakes with Large-Diameter Lockbolt Assemblies (BS 7805-2) - Setting a rivet outside its grip range, which leaves the joint loose from day one. - Using aluminum rivets on steel sheet outdoors — galvanic corrosion eats the rivet. ## Where Large-Diameter Lockbolt Assemblies (BS 7805-2) Are Not the Right Choice Not where the joint must later be disassembled, and not for high-tension structural connections. Custom manufacturing · Made to drawing ## Need a large-diameter lockbolt assemblies (bs 7805-2) outside the standard range? Body diameter, grip range, head form and body/mandrel material combination can all be specified against the joint rather than chosen from a table. Made by cold heading or drawing. Minimum order from 2,000 pieces; samples within 7 days of drawing approval. [Custom rivet manufacturing](https://engineeringhardware.com/custom/rivets/)[Send a drawing](https://engineeringhardware.com/custom/rivets/#rfq) ## Technical Drawing Dimensioned line drawing of 12.7 Large-Diameter Lockbolt Assemblies (BS 7805-2) to BS 7805 Part 2:1997. Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected. - **Pin head styles:** round / truss / countersunk / threaded-head - **Collar styles:** standard / flanged / low-profile - **Strength grade:** 8.8 - **Assembly:** pin + collar - **Material options:** steel / stainless steel / aluminum alloy ## Dimensions & Specifications (BS 7805 Part 2:1997) | Nominal diameter (mm) | Pin head styles | Collar styles | Strength grade | Assembly | Material options | Reference standard | | --- | --- | --- | --- | --- | --- | --- | | 12.7 | round / truss / countersunk / threaded-head | standard / flanged / low-profile | 8.8 | pin + collar | steel / stainless steel / aluminum alloy | BS 7805 Part 2:1997 | | 15.9 | round / truss / countersunk / threaded-head | standard / flanged / low-profile | 8.8 | pin + collar | steel / stainless steel / aluminum alloy | BS 7805 Part 2:1997 | | 19.1 | round / truss / countersunk / threaded-head | standard / flanged / low-profile | 8.8 | pin + collar | steel / stainless steel / aluminum alloy | BS 7805 Part 2:1997 | | 22.2 | round / truss / countersunk / threaded-head | standard / flanged / low-profile | 8.8 | pin + collar | steel / stainless steel / aluminum alloy | BS 7805 Part 2:1997 | | 25.4 | round / truss / countersunk / threaded-head | standard / flanged / low-profile | 8.8 | pin + collar | steel / stainless steel / aluminum alloy | BS 7805 Part 2:1997 | | 28.6 | round / truss / countersunk / threaded-head | standard / flanged / low-profile | 8.8 | pin + collar | steel / stainless steel / aluminum alloy | BS 7805 Part 2:1997 | | 31.8 | round / truss / countersunk / threaded-head | standard / flanged / low-profile | 8.8 | pin + collar | steel / stainless steel / aluminum alloy | BS 7805 Part 2:1997 | | 34.9 | round / truss / countersunk / threaded-head | standard / flanged / low-profile | 8.8 | pin + collar | steel / stainless steel / aluminum alloy | BS 7805 Part 2:1997 | 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 ### Can Large-Diameter Lockbolt Assemblies (BS 7805-2) joints be taken apart? No — rivets form a permanent joint and must be drilled out to remove. Use a bolt or screw where you need to disassemble the joint later. ### What material should Large-Diameter Lockbolt Assemblies (BS 7805-2) 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 Large-Diameter Lockbolt Assemblies (BS 7805-2) made to a recognized standard? Yes — they are manufactured to BS 7805 Part 2:1997, so dimensions are interchangeable between suppliers when you quote the standard on your order. ### What are Large-Diameter Lockbolt Assemblies (BS 7805-2) used for? Large-diameter swaged lockbolt joints in thick structural sections. They are supplied to BS 7805 Part 2:1997. ### Can I get a quote for Large-Diameter Lockbolt Assemblies (BS 7805-2) 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: [Large-Diameter Lockbolt Assemblies (BS 7805-2) — specifications & sizes](https://engineeringhardware.com/fastener/large-diameter-lockbolt-assemblies-bs-7805-2/) ### Large-Diameter Lockbolt Assemblies (BS 7805-2) Specification Guides ### Related Fastener Applications