Hey there, fastener fans, factory ops leads, and maintenance crews – let’s cut to a question we get at our industrial fastener shop literally every week: Can you reuse industrial fasteners? Industrial Fasteners
I know, I know – when you’re in a pinch, scrambling to grab a bolt from a disassembled old machine instead of waiting on a new order to arrive, that’s what seems like a total win. But here’s the thing: it’s not a straight “yes” or “no” answer. It depends on way more than just “does it fit.” As a supplier that’s been in this game (yes, I’m the guy who walks the warehouse floor at 6 a.m. to check incoming stock), I’ve seen way too many people mess this up, leading to breakdowns, shutdowns, even safety hazards. Let’s break this down like we’re chatting over coffee at the loading dock – no stuffy textbook jargon, just real-world stuff.
First, let’s stop lumping all industrial fasteners together. We sell everything from hex bolts and lag screws to heavy-duty structural bolts, eye bolts, and threaded rods – each has a totally different deal when it comes to reusing. Take a standard carbon steel hex bolt, the kind you use for assembling conveyor frames: that’s not a one-time use thing, right? But wait – it’s not unlimited, either. Then there’s a custom high-strength bolt for a crane’s lifting arm – that’s a whole different story. And don’t get me started on threaded fasteners with a prevailing torque feature, like lock nuts or torx bolts with nylon inserts. Those are basically designed to be throwaway once you take ’em off.
Let’s start with the science part (I promise it’s simple, not a PhD lecture). Every fastener – when you tighten it to spec – does two things: it stretches a tiny bit (that’s the preload, the force that holds the joint tight) and it forms small, almost microscopic indentations under the nut’s or bolt’s head where it presses against the surface. When you loosen a fastener, some of that stretch doesn’t bounce back – that’s called “permanent set.” If you stretch a rubber band, when you let go, it goes back. If you stretch it so hard it stays warped, that’s permanent set. The same thing happens with steel (or stainless steel, aluminum, whatever the fastener is made of).
That permanent set is the big culprit here. Let’s do a quick test I actually have our team run on new vs. used bolts: take two identical grade 8 hex bolts, one brand new, one we took off a forklift mast that only got torqued once and removed. Tighten both to 120 ft-lbs (the spec for that size) – the new one will stretch to exactly the preload it needs. The used one? It stretches less, because it’s already got that tiny bit of set from the first time. So when you reuse it, the preload is lower – and if preload drops below what’s required for the joint, that’s how parts wiggle loose, vibration rattles things apart, and suddenly your assembly line is down.
Wait, but isn’t there a case where that’s fine? Like, if you’re using a bolt to hold a shelf bracket in a drywall wall in your garage? That’s totally different – but industrial joints aren’t garages. These are under constant load, vibration, extreme temperatures, sometimes even corrosive environments. A conveyor bolt gets jostled every time a 500-lb box rolls over it. A wind turbine bolt on a farm takes the full force of wind gusts all day. Low preload here isn’t just an inconvenience – it’s a safety risk. We’ve had a customer call us at 2 a.m. a few years back because they reused a old bolt on a grain elevator’s housing, and it snapped mid-shift, spilling 20 tons of grain all over their loading dock. They had to shut down for 3 days, cost them $40k in downtime alone. That’s the kind of thing that makes us say, “Don’t cut corners on fastener reuse.”
But let’s not be total buzzkills – there are some fasteners you can reuse. I’m not gonna lie to you and say every single one is a waste. Let’s list the exceptions, because that’s what matters when you’re in a bind.
First: Low-load, non-critical joints. Like, a bolt holding a decorative guard on a machine (not part of a structural lift or load-bearing part) or a bolt on a HVAC unit’s housing that just keeps the cover on, no major stress. Even here, though, you have to inspect it first. No rust, no dents on the threads, no visible signs of cracking. If you can run a thread chaser through it and it glides, no snags, that’s a green light.
Second: Fasteners that weren’t torqued to spec the first time. Wait, hold on – let’s explain that. If a bolt was just hand-tightened (or barely wrenched) instead of torqued to the manufacturer’s spec, the permanent set is minimal. Because you never actually stretched it enough to get the plastic deformation. We’ve had a small fabrication shop bring us back a bunch of bolts they used for a test fit, never fully tightened, and we rechecked them – their preload was almost identical to new ones, so they reused them no problem. That’s a legitimate case, but only if you can confirm they never hit their torque mark.
Third: Stainless steel or aluminum fasteners with smooth, non-load-critical joints. These materials are softer, so their permanent set is a bit more forgiving, but only if the joint isn’t taking big loads. Again, inspect for thread damage or corrosion – if it’s clean, it’s okay.
Now, the big red flags – when you should never reuse a fastener, no exceptions. Let’s get these right, because this is where people mess up the most.
First: High-strength structural bolts (like ASTM A325 or A490, the ones used in bridges, building frames, heavy equipment). These are designed to be torqued to their yield point (the point where plastic deformation starts) to get maximum preload. Take ’em off, and they’ve already crossed that yield line once – so they’ll never hit the right preload again. We used to have a contractor bring us used A325 bolts from a bridge demo, tried to use them for a new warehouse’s beam connections. We stopped ’em right away and told them to get new ones – turns out, reused structural bolts have a 2x higher failure rate in tension loads, per the ASTM standards. That’s not a guess, that’s actual test data.
Second: Prevailing torque fasteners. Lock nuts (the ones with the nylon insert), self-locking bolts, all that stuff. The nylon insert wears out when you tighten and loosen it – once you take it off, that insert’s grip is gone. So a reused lock nut won’t lock anymore. Same with torx bolts with the deformed drive head – once you take a Torx bit out, the drive gets worn, so it slips when you torque it. We test these every week: a used lock nut will spin on a bolt 3 full turns without any resistance, a new one will stop half a turn. No good for vibration-heavy spots, like engine mounts or conveyor rollers.
Third: Fasteners with visible damage. Cracks (even tiny ones you might miss with the naked eye – run a finger over the threads, if it catches, toss it), rust, thread galling (that’s when threads stick together, usually from heat or corrosion), dents on the bolt head or nut. Rust is a big one – even surface rust on carbon steel can weaken the bolt by 10-15% when you reuse it. We have a quick rule here: if it looks worse than a new fastener that’s been on a shelf for 6 months, don’t reuse it.
Fourth: Fasteners used in corrosive environments. If a bolt was used outside, or in a place with chemicals, salt, or high humidity, the threads and surface are already compromised. Corrosion eats at the metal, and the permanent set becomes uneven, so when you reuse it, preload is all over the place. We had a seafood processing plant bring us used bolts from their conveyors – those were sitting in salt water daily, so even if they looked fine, we told ’em to replace ’em. They listened, and their downtime went down 25% after that.
Wait, what about reusing nuts and bolts together from the same assembly? A lot of people ask that – if I take a nut off a bolt they’re a matched pair, can I use ’em again? The answer is maybe, but only if both are in great shape. They’re a matched pair because when they were tightened, the nut’s threads and the bolt’s threads wore in together a tiny bit. If you match ’em to a different fastener, that wear pattern might not line up, leading to loose threads or lower preload. So if you can keep the pair together, that’s better, but only if they’re undamaged.
Now, let’s talk about what we do here, as your local industrial fastener supplier, to help you navigate this. We don’t just sell you bolts – we’re on your side to keep your operations running, so we’ve got a few quick checks you can do on the spot to tell if a fastener is reusable.
- Thread Check: Run a new nut (or a thread chaser) over the used bolt’s threads. If it glides smoothly without catching, snags, or skipping threads, it’s good. If it sticks, toss it.
- Preload Check (rough version): If you have a torque wrench, tighten the used fastener to half its spec. If it takes the same amount of force as a new one, it’s probably still got good preload. If it takes less force, it’s got too much permanent set.
- Visual Inspection: Hold it up to a light – no cracks, no deep dents, no thick rust. The head shouldn’t be stripped (no rounded edges on hex bolts, no phillips head holes that are worn out).
- Lock Feature Test: For lock nuts, spin a new bolt through the nut. If it spins more than a full turn without resistance, the nylon insert is worn – trash it.
We also keep a stock of “reusable-grade” fasteners for customers who work on low-load, non-critical projects. They’re bolts that were test-fitted, never fully torqued, and checked for minimal wear – way cheaper than new, but only for the right jobs. That’s the kind of thing we don’t advertise super loud, but if you ask, we’ll hook you up.
Wait, let’s address a common myth I hear all the time: “I can reuse any fastener as long as I clean the threads.” Cleaning threads with a wire brush is great, but it doesn’t fix permanent set, and it doesn’t bring back a worn nylon insert, or fix a tiny crack that’s hidden under rust. We see people do this all the time, and it almost always ends with a call to us because their machine is down. Cleaning is a step, but it’s not a magic fix.
Another myth: “Grade 5 bolts can be reused, grade 8 can’t.” Nope, that’s not right. It’s not the grade, it’s the load and whether it’s a critical joint. A grade 5 bolt used for a shelf bracket is way safer to reuse than a grade 8 bolt used for a crane’s boom. The grade just tells you how strong the metal is, not whether it can take being loosened and re-tightened.
Let’s wrap this up with a real example from last month. We had a customer who runs a packaging plant – they were swapping out a conveyor belt, and had a bunch of hex bolts they’d used to hold the old belt tensioner. They pulled a few, cleaned ’em, and tried to reuse ’em for the new tensioner. Our warehouse foreman, Jake, stopped them – did a quick thread check, noticed a tiny snag on one bolt, and pulled it. Turns out, that snag was from when the old tensioner had been adjusted a few times, so the threads were already damaged. If they’d reused it, that bolt would’ve snapped within a week, and their packaging line (which runs 24/7) would’ve shut down. That’s the kind of call we make all the time – we’re not here to sell you new fasteners every time, we’re here to save you downtime and money.
So to answer the original question: Yes, you can reuse some industrial fasteners – but only if you’re in a low-load, non-critical joint, you inspect it thoroughly for damage or wear, and it’s not a lock-type fastener, high-strength structural bolt, or one that was used in a corrosive environment. If it’s a critical load-bearing part (like a lift, structural frame, engine component), just buy new. The $0.20 you save on a bolt now isn’t worth the $40k in downtime later.
At the end of the day, we’re here to help. If you’ve got a pile of used fasteners and aren’t sure if they’re reusable, just send us a pic, or swing by our warehouse – we’ll take 2 minutes to check ’em for you. No pressure, no upsell, just helping you make the right call.
If you’re working on a project and need fasteners that are reliable, or if you’ve got questions about which ones are safe to reuse, hit up our team to chat through your needs. We’ve got stock of all grades, sizes, and even reusable-grade fasteners for your low-stakes jobs – and we’ll never steer you wrong.
Steam Turbine Seals References
- ASTM International. (2020). Standard Specification for High-Strength Steel Bolts, Studs, and Nuts for Structural Steel Bolting (A325/A325M).
- Industrial Fasteners Institute. (2021). Reuse of Threaded Fasteners: Best Practices for Manufacturing and Maintenance.
- Society of Automotive Engineers. (2019). Fastener Preload Analysis for Reuse Applications in Non-Critical Joints (SAE J1567).
Hebei Guoyuan Electric Co., Ltd.
Address: No. 18 Tianshan Science and Technology Industrial Park, No. 319 Xiangjiang Road, Shijiazhuang High-tech Zone, Hebei Province, China
E-mail: turbine@goineep.com
WebSite: https://www.goineep.com/
