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Q Are D&D concealed hinges certified for fire-rated doors?
A Yes. Our DDCH008 and DDCH011 models are UL 10C fire rated under File No. R38013 for the North American market, and certified to BS EN1935 (200,000 cycles), EN1634 fire rated 132 minutes, and EN1670 corrosion resistance 48 hours for European markets. The fire-resistant construction includes an expanding graphite seal, ceramic fire-retardant coated fasteners, and a 304 stainless steel cover plate rated to 1000°C — suitable for fire-rated metal doors, wooden fire doors and smoke doors.
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Q What is a concealed door hinge and how is it different from a butt hinge?
A A concealed door hinge — also called an invisible hinge or hidden hinge — is mortised into the door leaf and frame so it is completely invisible when the door is closed. Unlike a butt hinge, it has no exposed knuckle or removable pin. That means a seamless flush appearance, better tamper resistance, and precise 2D or 3D alignment adjustment after installation, which a traditional butt hinge cannot offer.
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Q Do you offer OEM or custom branding options?
A Yes. D&D Hardware offers comprehensive OEM/ODM services including custom logo stamping or laser marking on hinge leaves, custom packaging with your branding, and tailored finishes or sizes to meet specific project requirements. Our experienced engineering team works closely with clients to develop custom solutions. Minimum quantities for OEM orders typically start at 500 pairs per SKU.
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Q Can I get samples before placing a bulk order?
A Yes. We provide free product samples so you can evaluate hinge quality, finish, and fit before placing a bulk order. Sample requests are typically processed within 3–5 business days. Simply reach out through our inquiry form or contact us directly, and our team will arrange sample shipment to your specified address.
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Q What is the MOQ for D&D ANSI/BHMA certified hinges?
A We offer flexible minimum order quantities to accommodate projects of all sizes. For first-time trial orders, there is no minimum order requirement — allowing you to evaluate our product quality before committing to larger volumes. Standard bulk orders typically start at 500 pairs per size/finish combination. Contact our sales team for specific MOQ details based on your project requirements.
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Q Does D&D support OEM programs, custom finishes and bulk distributor pricing?
A Yes. As the factory, D&D supports private labeling, custom packaging, PVD and matte black finishes, stainless steel 201/304/316 material options and volume pricing structures for distributors, importers and door manufacturers. Custom sizes are available on request alongside the 11 certified standard sizes.
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Q What documentation does D&D provide for project submittals and procurement?
A Every quotation can include independent laboratory test reports, ANSI/BHMA certificates for A156.1 and A156.18, UL listing documentation, material certificates and finish specifications — formatted for architect review, building control submission and distributor compliance files.
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Q Are these hinges compatible with fire-rated door assemblies?
A Yes. D&D ANSI/BHMA hinges carry UL/cUL UL 10C certification with a 3-hour fire rating under File No. R38013, satisfying NFPA 80 and IBC requirements for fire door assemblies. See our dedicated UL fire door hinge guide for listing details and certified sizes.
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Q When should NRP (non-removable pin) hinges be specified?
A Specify NRP on any out-swinging exterior or security-sensitive door where the hinge barrel is exposed to the unsecured side. The set screw locks the pin in place while the door is closed, eliminating pin extraction as a forced-entry route. NRP is available across D&D's Grade 1 and Grade 2 configurations.
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Q What is the practical difference between A156.1 and A156.18 certification?
A A156.1 certifies the mechanical performance of the hinge itself — cycles, wear, friction and strength. A156.18 certifies the finish: corrosion resistance via 240-hour ASTM B117 salt spray, adhesion and color consistency. A complete commercial submittal should reference both, which is why D&D certifies its range to the two standards together.
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Q Why should a commercial project never specify Grade 3 hinges?
A Grade 3 is tested to only 350,000 cycles — designed for light residential service. Under commercial traffic it produces door sag, latch misalignment and cascading damage to closers and locks, forcing early replacement. The labor cost of one replacement typically erases any purchase saving several times over.
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Q How do I translate hinge cycle tests into expected service life?
A Divide the certified cycle count by realistic daily usage. A Grade 1 hinge (2,500,000 cycles) on a high-traffic entrance operating 200 times daily gives a theoretical mechanical life of over 34 years; at 100 cycles per day it exceeds 68 years. This calculation is the backbone of any total-cost-of-ownership comparison a facility manager will accept.
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Q Can D&D hinges be used on projects outside Europe that require CE standards?
A Yes. While CE marking is mandatory within the European Economic Area, many international projects — particularly in the Middle East (UAE, Saudi Arabia, Qatar), Southeast Asia (Singapore, Malaysia), Africa, and Oceania — specify CE/EN standards for commercial fire door hardware. D&D currently exports CE-certified hinges to over 30 countries worldwide. Our documentation is formatted to meet the submission requirements of various national building authorities, and our export team is experienced in handling the specific compliance documentation required by different markets.
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Q How many hinges are needed per fire door, and does hinge count affect fire rating?
A The number of hinges required is determined by the door's height, weight, and the fire door assembly certification. As a general guideline: doors up to 2100mm height typically require 3 hinges; doors between 2100-2700mm require 4 hinges; and doors exceeding 2700mm may require 5 or more. The fire rating is tested per hinge — so each individual hinge must carry the appropriate EN1634 certification regardless of how many are installed. Using fewer hinges than specified can void the fire door assembly certification. D&D's technical team can advise on the correct hinge count based on your specific door manufacturer's assembly certification.
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Q Which stainless steel grade should I specify for my application?
A The choice depends on your installation environment. SS201 is suitable for interior applications in dry, controlled environments where cost optimization is a priority. SS304 is the standard recommendation for most commercial interior fire doors — it provides excellent corrosion resistance for indoor environments including kitchens, bathrooms, and areas with moderate humidity. SS316 is specified for exterior fire doors, coastal buildings (within 5km of saltwater), swimming pool areas, chemical processing facilities, and any environment with chloride exposure. All three grades carry the same CE certification and fire rating — the difference is in long-term surface corrosion performance.
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Q Do you offer OEM private labeling and custom packaging?
A Absolutely. As a factory-direct manufacturer, D&D provides comprehensive OEM services tailored to door manufacturers and hardware distributors. This includes: laser-engraved or stamped brand logos on hinge leaves, custom retail or bulk packaging with your branding, bespoke finish development to match your product line aesthetic, and custom size engineering for non-standard door preparations. Our OEM team works closely with your product development and marketing departments to deliver a finished product that integrates seamlessly into your brand portfolio.
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Q What is the minimum order quantity and lead time for CE hinges?
A D&D offers flexible ordering options to suit different buyer types. For standard sizes in stock finishes (SSS, PSS), we maintain inventory for rapid dispatch with competitive MOQs suitable for distributors and smaller projects. For OEM orders with custom finishes, private labeling, or non-standard sizes, MOQs are quoted based on the specific requirements — typically starting from 500-1000 pieces per size depending on complexity. Standard production lead time is 15-30 days from order confirmation. We also support phased delivery schedules for large construction projects requiring staged hardware supply.
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Q Can you supply CE certification documents for building inspections and insurance?
A Yes. D&D Hardware provides a complete certification package for every order: Declaration of Performance (DoP) per CPR No. 305/2011, third-party test reports from accredited European laboratories, CE mark certificates with unique identification numbers, and technical data sheets. These documents are formatted for direct submission to building control authorities, insurance underwriters, and project handover documentation. We can provide documents in advance during the specification stage to support your tender submissions.
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Q How does the 260-minute fire rating compare to standard requirements?
A Most European building regulations require fire doors rated between FD30 (30 minutes) and FD120 (120 minutes) depending on the building type and compartmentation strategy. D&D's 260-minute fire rating for steel doors exceeds even the most stringent FD240 requirement, providing a substantial safety margin. This extended rating is particularly valuable for high-risk applications such as industrial facilities, data centers, and healthcare buildings where maximum passive fire protection is specified. The 192-minute rating for wooden doors similarly exceeds FD120 requirements common in commercial construction.
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Q What is the difference between CE Grade 13 and lower hinge grades?
A Grade 13 under EN1935 represents the highest practical performance level for commercial door hinges: 200,000 open/close cycles tested at 120kg door mass. Lower grades (e.g., Grade 7 at 40kg, Grade 11 at 80kg) may be adequate for lighter residential doors but are insufficient for heavy commercial fire doors that experience high daily traffic. For steel fire doors in commercial buildings — which typically weigh 20-160kg — Grade 13 is the recommended specification to ensure the hinge maintains smooth operation and structural integrity throughout the door's 20+ year service life.
