Do sealants in a silo need food grade certification
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Do sealants in a silo need food grade certification?
A bolted silo is assembled from factory-finished panels joined by bolts and sealed at every joint. The sealant that fills that joint is in direct contact with the stored grain along the entire wall, which makes it a food-contact material exactly like the wall coating. Specifying a certified wall and forgetting the sealant is a common and consequential gap, because the joint line is precisely where an uncertified compound would leach into the grain.
Shijiazhuang Zhengzhong Technology Co., Ltd. (Center Enamel) supplies bolted grain silos with both the enamel wall and the joint sealant selected for food-contact compliance, and treats the sealant certificate as part of the same deliverable as the wall certificate.
1. The Sealant Is in the Food Path
Every horizontal and vertical bolted joint in a silo contains sealant, and grain presses against those joints across the full height of the wall. The contact is continuous and long-duration - months, not minutes - so any substance the sealant can release has ample opportunity to migrate into the grain. The sealant is therefore not a minor fitting; it is a food-contact surface in its own right.
· Full-Height Contact: Joints run the height of the wall and touch grain throughout.
· Long Duration: Grain rests against the joint for months at a time.
· Continuous Path: Every panel joint contains sealant in the grain zone.
· Same Risk as Wall: It can migrate into food just like the coating.
· Often Overlooked: Specifications name the wall but omit the sealant.
2. The Same Food Rules Apply
The sealant must meet the same food-contact regulation as the wall: FDA 21 CFR in the United States, EU 1935/2004 (with 10/2011 for any polymer portion) in Europe, and LFGB in Germany. Because many sealants are polymer-based, the plastics migration rules can apply directly, and the compliance statement should name the regulation and the certified formulation, not a generic 'food safe' description.
· Same Regulations: FDA, EU 1935/2004 and LFGB all cover the sealant.
· Polymer Rules: 10/2011 may apply to the polymer portion of the sealant.
· Named Formulation: The certificate should specify the exact sealant recipe.
· Not Generic: A 'food safe' label without a regulation is not evidence.
· Matched to Wall: Wall and sealant should be certified to the same market.
3. Specifying the Sealant Correctly
The specification should require the joint sealant to carry food-contact compliance for the target market, name the exact product, and be delivered with its statement alongside the wall certificate. It should also confirm the sealant is compatible with the stored grain - some aggressive or oily crops can affect certain polymers - and that it remains serviceable across the expected temperature range.
· Require the Statement: Ask for the sealant's food-contact document explicitly.
· Name the Product: Specify the exact certified sealant, not a class.
· Deliver Together: Sealant and wall certificates belong in one file.
· Check Crop Compatibility: Some oily or high-moisture crops stress polymers.
· Temperature Range: Confirm the sealant stays effective at site temperatures.
Design parameter | Typical value or range | Why it matters |
Sealant contact | Full wall height, months | A continuous food-contact surface |
Applicable rule | FDA / EU 1935/2004 / LFGB | Same as the enamel wall |
Polymer portion | EU 10/2011 if present | Plastics migration limits may apply |
Crop compatibility | Confirm for oily or moist grain | Some polymers are stressed |
Documentation | Sealant statement with wall cert | Both in one file |
Limitation to check | Generic 'food safe' is not evidence | Require the named regulation |
Item | Food-contact status | Rule applied | Common gap |
Enamel wall | Required | FDA / EU 1935/2004 / LFGB | Usually specified |
Joint sealant | Required | Same rules; 10/2011 if polymer | Often omitted |
Bolts and washers | Confirm if wetted | Same rules | Rarely checked |
Internal fittings | Required | Same rules | Sometimes omitted |
Engineering Assurance and Project Support
Every tank delivered by Shijiazhuang Zhengzhong Technology Co., Ltd. (Center Enamel) is engineered against AWWA D103-09 and EN 1090 with finite element verification of shell, roof and nozzle loads, fused at 820-930°C under ISO 9001 and ISO 45001 control, holiday tested at 1500 V across one hundred percent of the surface, and assembled with Grade 8.8 bolts and manufacturer-certified sealant. Bolted grain silos are supplied with both the enamel wall and the joint sealant certified for food-contact compliance in the target market, the sealant product named in the specification, and both certificates delivered together at handover with the tank records.
Yes - in a bolted silo the joint sealant is a food-contact surface and needs its own certification under the same rule as the wall. Forgetting it is the single most common compliance gap in grain silo specifications.
Frequently Asked Questions (FAQ)
Can I use any industrial sealant if the wall is certified?
No. An uncertified industrial sealant in the joint can leach into the grain and invalidate an otherwise compliant silo. The sealant must carry its own food-contact statement for the target market, matched to the same regulation as the wall.
Does the sealant need to be inert like enamel?
It needs to be certified, not necessarily enamel. Polymer sealants are common and acceptable when listed under the applicable food-contact rule, including 10/2011 where polymers are present. The point is certification and crop compatibility, not the material family.
What if the silo stores animal feed, not human food?
Feed is covered by related rules (LFGB includes feed, and feed-hygiene regulations apply in the EU), so the sealant should still be selected for contact safety. Even for feed, an uncertified sealant is a needless risk and a potential audit finding.
Can the silo be customized to our grain and market?
Yes. Wall and sealant food-contact status for the destination, cone or flat bottom, aeration and ventilation, temperature monitoring and the compliance documentation are all configured to the crop and market, delivered at handover.
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