SOSS 418SS Stainless Steel Inv...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$363.40
$273.00
SOSS 418SS Stainless Steel Invisible Hinge with 90/180-Minute Fire Rating

SOSS 418SS Stainless Steel Invisible Hinge with 90/180-Minute Fire Rating

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Model: 418SSUS32D
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In Stock (leaves warehouse same day if ordered before 3pm ET)

$363.40
$273.00
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SOSS 418SS Stainless Steel Invisible Hinge with 90/180-Minute Fire Rating

The SOSS 418SS Invisible Hinge is engineered for wood or metal doors that are 1-3/4" thick, delivering a flush fit and compact concealed profile for full sized entry applications. Constructed entirely of 316 stainless steel, this heavy-duty hinge opens a full 180° as a single action hinge and resists corrosion in exterior, wood, and metal installations. Underwriters Laboratories has labeled the 418SS for use on hollow metal, sheet metal, tin clad, and steel composite swinging fire doors and frames rated up to and including 3 hours, wood core doors and frames rated up to 20 minutes, and wood/plastic composite doors and frames built with Georgia Pacific FS 1 or FS 2 banding rated up to and including 90 minutes. Wood and machine screws are included for straightforward installation.

Key Features

  • Material Thickness Compatibility: Designed for wood or metal doors and frames with a minimum material thickness of 1-3/4" for proper flush installation.
  • Heavy-Duty Corrosion Resistance: Made of complete 316 stainless steel construction, ideal for exterior applications and environments requiring superior corrosion resistance.
  • Full 180° Single Action Operation: Provides smooth, reliable swing operation across a full range of motion for full sized entry doors.
  • Invisible Concealed Design: Flush fit and compact size deliver a clean appearance while maintaining durability in high-use commercial settings.
  • Fire-Rated Performance: UL labeled for use on hollow metal, sheet metal, tin clad, and steel composite fire doors rated up to and including 3 hours, wood core doors rated up to 20 minutes, and wood/plastic composite doors with Georgia Pacific FS 1 or FS 2 banding rated up to and including 90 minutes.
  • Included Hardware: Wood and machine screws are included, and counter bored screw holes are not required for this model.
  • Application Guidance: Use at least one fire-rated hinge for every 20" of door height or portion thereof, or one hinge for every 60 lbs. or fraction thereof, whichever demands more hinges.
  • Rounded Corner Design: Part of the 418 Series, featuring a rounded corner profile and a product size of 4-39/64" for compatible door preparation.

Certifications & Compliance

  • UL Labeled for Fire Door Applications
  • Fire Rating: 90 / 180 Minutes

Technical Specifications

  • Subcategory: Hinges and Pivots
  • Product Group: Door Hinges and Pivots
  • Product Subgroup: Concealed Hinges
  • Commercial/Residential: Commercial
  • Duty Level: Heavy Duty
  • Electronic: No
  • Corner Type: Rounded
  • Series: 418 Series
  • Product Size: 4-39/64"
  • Product Category: Door Hinges and Pivots
  • Department: Door Hardware
  • Application: Exterior, Full Sized Entry, Metal, Wood
  • Min. Material Thickness: 1-3/4″
  • Fire Rating: 90 / 180 Minutes
  • Power Transfer: No
  • Closer: No
  • Counter Bored Screw Holes: No
  • Screws Included: Wood and Machine
  • Packaging: 1 / Box = 1 Each
  • Packages Per Container: 1 Each
  • Price Per: Each

Typical Applications

  • Commercial Office Buildings
  • Educational Facilities
  • Healthcare Institutions
  • Retail Establishments
  • Industrial and Warehouse Facilities
  • Multi-Tenant Residential Properties
  • Government and Municipal Buildings

Why SOSS 418 Series?

SOSS 418 Series hinges deliver professional-grade reliability with complete 316 stainless steel construction and UL-labeled fire ratings up to 3 hours on qualifying door and frame assemblies. Engineered for demanding commercial entry applications where flush appearance, smooth single action operation, and long-term corrosion resistance are essential.

Product Specs

Subcategory:
Hinges and Pivots
Product Group:
Door Hinges and Pivots
Product Type:
Invisible Hinges
Product Subgroup:
Concealed Hinges
Commercial/Residential:
Commercial
Duty Level:
Heavy Duty
Electronic:
No
Corner Type:
Radius
Series:
418 Series
Product Function:
Invisible Hinges
Product Size:
4-39/64"
Product Category:
Door Hinges and Pivots
Product Substrate:
Stainless Steel
Department:
Door Hardware

SOSS 418SSUS32D – Frequently Asked Questions

1) Will the SOSS 418SS invisible hinge work on a 1-3/4 inch door?
That's exactly what the 418SS is built for. It calls for wood or metal doors and frames with a minimum material thickness of 1-3/4 inches, which is the standard commercial door thickness. Thinner doors and frames don't give the mortise pocket enough material for a flush concealed install, so on a 1-3/8 inch interior door you need a smaller SOSS model, not this one.
2) Can I use the SOSS 418SS on a fire rated door, and what rating does it carry?
Yes, and the rating depends on the door assembly, not the hinge alone. Underwriters Laboratories labeled the 418SS for hollow metal, sheet metal, tin clad and steel composite swinging fire doors and frames rated up to and including 3 hours; wood core doors and frames up to 20 minutes; and wood/plastic composite doors and frames built with Georgia Pacific FS 1 or FS 2 banding up to and including 90 minutes. So the same hinge gives you 3 hours on a hollow metal opening and 20 minutes on a wood core one. Match the rating to the door you actually have.
3) Is the SOSS 418SS suitable for an exterior door or a coastal, high humidity building?
Yes. The 418SS is built entirely of 316 stainless steel, which is the corrosion resistant grade you want on exterior openings, pool rooms, coastal sites and washdown areas. It's listed for exterior, metal and wood applications. Note it is not just a stainless finish over another base metal, the construction is 316 throughout.
4) What size mortise do I need to rout for the SOSS 418SS, and are the corners square or rounded?
The 418SS is a 4-39/64 inch hinge with a radius corner profile, so a router with a bearing guide cuts the pocket without needing corner chisel work to square it out. Cut the door edge and the jamb to the template dimensions before hanging; SOSS publishes both a 418SS model drawing and a hinge location drawing for laying out the pocket positions on the door height.
5) What is an invisible hinge and when should I use one instead of a butt hinge or a pivot?
An invisible hinge mortises into the edge of the door and into the jamb, so nothing shows when the door is closed, on either face. The 418SS is the concealed choice where you want a flush, unbroken look on a full sized entry door and you still need a fire rated, heavy duty commercial hinge. A butt hinge is easier to install and easier to swap later because it screws to the surface of the door edge and jamb rather than into a routed pocket. If nobody cares that the hinge is visible, a butt hinge is less prep work. If the appearance of the door face and edge matters, or the design calls for a flush door with no visible hardware, that is what the 418SS solves.
6) How far does the SOSS 418SS open, and will the door clear a wall or adjacent trim?
180 degrees, as a single action hinge, so the door swings one way through a full half circle. That full swing needs the jamb and casing detailed to suit, so check the opening geometry on a cased jamb before you rout. SOSS publishes the 418SS clearance detail, the cased jamb detail and a 90 degree open drawing that show exactly how the leaves fold and what space they take.
7) Do the SOSS 418SS hinges come with screws, or do I need to buy fasteners separately?
Both wood and machine screws ship in the box, so you're covered whether you're going into a wood door or a hollow metal frame. Counter bored screw holes are not required on this model, which means no extra prep beyond the mortise itself.
8) Does the SOSS 418SS need handing, or is one hinge good for a left or right hand door?
No handing to specify on the 418SS. It is a single action invisible hinge that mortises symmetrically into the door edge and jamb, so the same part works on a left hand or right hand opening. What you do have to get right is the count, the 1-3/4 inch minimum material thickness, and the finish.
9) Can I add a closer or run power through the SOSS 418SS for an electric strike or maglock?
No on both counts. The 418SS is a mechanical hinge with no power transfer path and no built in closer, so it can't carry wiring to an electrified lock, exit device or monitoring contact. If the opening needs current at the door, plan on a separate electric power transfer device or a door loop, and specify a surface or concealed closer independently.
10) What finishes does the SOSS 418SS come in, and which one matches my existing hardware?
Two: 629 bright stainless steel and 630 satin stainless steel. 630 satin is the workhorse commercial finish and is what most lever trim, exit devices and butt hinges in an office, school or healthcare building are specified in, so it's the safer match for standardizing an existing fleet of openings. 629 is the polished bright version for a more decorative entry. Since the hinge is concealed when the door is shut, the finish only reads on the exposed edge when the door is open.
11) Is the SOSS 418SS heavy duty enough for a high traffic commercial entrance?
It's classified commercial and heavy duty, and built for full sized entry doors in offices, schools, healthcare facilities, retail, industrial buildings, multi-tenant residential and government work. Size the number of hinges to the door: one per 20 inches of height or one per 60 lbs of weight, whichever gives the higher count. On a heavy exterior door that calculation, not the duty rating, is what usually decides how many you buy.
How fast can I get the SOSS 418SSUS32D delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the SOSS 418SSUS32D come with a warranty?
Absolutely. The SOSS 418SSUS32D is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the SOSS 418SSUS32D?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
Why buy the SOSS 418SSUS32D from ZenSupply?
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