If you’ve ever stood on the floor of a food processing plant, watching stainless steel conveyors hum, mixing tanks rotate, and conveyor belts glide with fresh produce, you might have glanced at a hex bolt and thought, “Is that really safe here?” As a hex bolt supplier with 12 years of experience serving manufacturing sectors—from automotive to renewable energy—food processing has always felt like a space where our hardware’s performance isn’t just about holding parts together, but about protecting public health. Over the past decade, I’ve fielded questions from plant managers, maintenance supervisors, and even process engineers: Can hex bolts even be used in food processing equipment? The short answer is yes—but only if you get the right kind, and that’s where a lot of teams go wrong. Hex Bolt
Let me start with the most common mistake I see in this space: using generic steel hex bolts because they’re cheap and easy to source. A standard plain carbon hex bolt (the kind you’d use for a backyard fence or a basic machinery frame) has no protective coating, or a coating like zinc that can chip, flake, or leach toxins when exposed to acidic foods, high heat, or constant washdowns. I once had a call from a fruit canning plant in the Midwest that had to shut down a line for 36 hours because plain zinc-plated hex bolts holding their mixing tank’s top guard had corroded. The zinc flaked off into the apple puree, and even though the levels were low enough for the food to be unharmed by human consumption, the plant had to dump 20,000 cases of product and retest every part of the line to get back into compliance. That’s a $120,000 mistake, all because they tried to save 50 cents per bolt. That’s why, when we talk about hex bolts for food processing, material is non-negotiable.
The gold standard here is 304 or 316 grade austenitic stainless steel hex bolts. I know it sounds like jargon, but let me break it down simply. 304 is the most common stainless steel, made with 18% chromium and 8% nickel—it resists corrosion from mild acids, water, and regular cleaning chemicals, which makes it perfect for dry storage areas, low-acid dry food processing (like cereal or flour), and equipment that only needs monthly washdowns. But if you’re working with high-acid foods—think citrus juice, tomato products, or pickles—or you need equipment to handle high-temperature steam washdowns (common in poultry or seafood processing), you need 316 stainless steel. 316 adds 2-3% molybdenum, which creates an extra barrier against pitting corrosion, the kind that happens when salt or acidic foods get trapped in tiny scratches on a bolt’s surface. That pitting not only weakens the bolt over time, but it can also harbor bacteria like E. coli or Salmonella, which are a major risk in food processing.
Wait a second, I can already hear the pushback: “Why not use a different fastener, like a square bolt or a carriage bolt, for food processing?” That’s a fair question. Square bolts have a flat shank that locks into a nut, which might sound like it prevents bacteria buildup, but they have sharp, crevice-ridden edges that are way harder to sanitize than the smooth, uniform head of a hex bolt. Carriage bolts have a round head and a square neck under the head to lock into wood or soft metal, but that square neck creates gaps where food residue can get stuck—gaps a spray nozzle can never fully reach. Hex bolts, when installed with the right washers and nuts, have a smooth, continuous surface that’s easy to wipe down, which is a huge win for food safety.
But even with the right material, there’s more to choosing a food-grade hex bolt than just pulling a 316 grade off the shelf. Let’s talk about surface finish. A lot of suppliers will sell “polished” bolts as food-grade, but most of those are only polished to look shiny—they still have a surface roughness (measured in Ra, or microinches) of around 32 Ra, which is enough to trap food particles and bacteria. For food processing, we specify bolts with a surface finish of 16 Ra or lower. That ultra-smooth surface is like a non-stick pan for bolts—food and bacteria can’t cling to it, so when you spray the line down with a sanitizer, every last bit of residue is gone. I remember a craft brewery client who switched from 32 Ra hex bolts to 16 Ra ones for their mash tuns and fermenters. They told me their pre-operational swab tests dropped by 85% in the first month, because the old bolts’ rough surfaces had been holding onto yeast and malt residue even after deep cleaning.
Another often-overlooked detail is the nuts and washers you pair with your hex bolt. A bolt is only as food-safe as the weakest part of its assembly. If you use a standard steel nut with your stainless steel hex bolt, the two different metals will create a galvanic reaction when exposed to moisture. That reaction causes the nut to corrode, and over time, corrosion products can leach into the food. We always recommend matching 304 or 316 stainless steel nuts and washers, and for even better corrosion resistance, we use serrated lock washers that won’t vibrate loose during operation (a common issue in moving equipment like conveyor systems). For areas that are exposed to constant water or cleaning chemicals, I also suggest using hex bolts with a closed-end head, not an open slot or hole, because open ends can trap water and residue.
Now, let’s address a question I get almost weekly: “Are there any regulations that specify what kind of hex bolts I can use in food processing equipment?” Yes, and they’re not just suggestions—they’re enforced by the FDA in the U.S., and similar bodies like the EFSA in Europe. The FDA’s Food Safety and Modernization Act (FSMA) requires all food contact materials to be non-toxic, non-reactive, and capable of withstanding the conditions of their intended use. That means plain carbon steel, zinc-plated, or cadmium-plated hex bolts are a hard no for food contact surfaces—those coatings are made for durability, not for meeting food safety standards. We also see a lot of clients ask about bolts with PTFE or Teflon coatings, but those coatings can chip when exposed to high heat or heavy vibration, and the FDA doesn’t approve them for most high-acid food applications. Sticking to uncoated 304 or 316 stainless steel is the only way to stay in compliance, and that’s something I make sure every new client knows from our first conversation.
I also want to talk about something that’s near and dear to me: real-world testing. When I first started in the hex bolt business, I thought all 316 stainless steel bolts were created equal. I made a big mistake once: I sold a batch of “316” bolts to a vegetable processing plant, and they corroded within 6 months. Turns out, that bolt was only 316 on the surface—subsequent testing showed the core was a lower grade of stainless steel, which couldn’t handle the salt brine the plant used for blanching. That mistake cost me a long-term client, and it taught me a lesson I still carry today: never cut corners on quality. Now, every batch of hex bolts we supply to food processing clients comes with a material test report (MTR) that verifies the exact grade and composition of the steel, so there’s no guesswork. We also work with a third-party lab to test a sample of every shipment for corrosion resistance, using the salt spray test (ASTM B117) that simulates years of exposure to moisture and chemicals. For food processing, we require a minimum of 1,000 hours of salt spray resistance for all our bolts, which is twice the industry standard for general stainless steel hardware.
Let’s circle back to the original question: Can hex bolts be used in food processing equipment? The answer is a resounding yes, but only when you select the right material, surface finish, and assembly. Generic hex bolts are a risk to your product, your line, and your brand. But food-grade hex bolts—uncoated 304 or 316 stainless steel, with a smooth, low-roughness surface, and matched with the right nuts and washers—are a safe, reliable choice that meets all regulatory standards and holds up to the harsh conditions of food processing floors.
Over the years, I’ve seen plants switch to the right hex bolts and cut their maintenance downtime by 40%, reduce food waste from contamination by 25%, and pass every FSMA audit with zero non-conformances. It’s not about buying the cheapest bolt on the market—it’s about buying a bolt that does exactly what you need it to do: hold your equipment together, protect your product, and keep your line running safely.
If you’re currently using hex bolts in your food processing equipment, or if you’re looking to upgrade your fasteners to reduce risk and improve compliance, I’d love to hear from you. We work with plants of all sizes, from small craft bakeries to large multinational meat processing facilities, and we can help you audit your current hardware, find the right hex bolts for your specific application, and provide all the documentation you need for audits and compliance. Don’t let a cheap bolt ruin months of hard work or thousands of dollars in product—let’s talk about making your line safer, one bolt at a time.
Nuts References:
- U.S. Food and Drug Administration. (2023). Food Contact Substances: Materials of Construction. Retrieved from FDA.gov
- American Society for Testing and Materials. (2022). Standard Practice for Operating Salt Spray (Fog) Apparatus. ASTM B117-22
- National Sanitation Foundation. (2021). Standard 2: Food Equipment Materials. NSF/ANSI 2-21
Hebei Kappa Metal Products Co., Ltd.
Hebei Kappa Metal Products Co., Ltd. is one of the most experienced hex bolt manufacturers and suppliers in China. With a professional production team, we are able to meet the needs of the majority of our customers. Please rest assured to buy bulk high quality hex bolt in stock here from our factory.
Address: C2-11, Hebeipu Standard Parts Industrial City, Linmingguan Town, Yongnian District, Handan City, Hebei Province
E-mail: rick@kappafasteners.com
WebSite: https://www.kappafasteners.com/
