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What is DIN7989?
DIN7989 is a German industrial standard that specifies the dimensions, technical requirements, and delivery conditions for thick washers used in steel structures.
📌 Key Characteristics
The primary feature of these washers is that they are thicker and have a larger outer diameter compared to standard flat washers (like those defined by DIN125). This provides a larger contact surface area, which helps distribute the load from the bolt or nut more effectively. This reduces the risk of crushing or damaging the connected material.
🔧 Typical Applications
Due to their superior load-bearing capacity, these heavy-duty washers are commonly used in applications that demand high strength and stability, such as:
· Heavy timber construction (e.g., decks, docks)
· Steel construction
· Any heavy-duty connection requiring greater support from the fastener
📑 Standard Structure & History
The DIN7989 standard currently consists of two parts, which specify different product grades:
· DIN 7989-1: Product Grade C
· DIN 7989-2: Product Grade A
Both parts were published in April 2001, superseding a single, older version from 1974.
📏 Main Technical Specifications
Key technical requirements defined by the standard include:
· Dimensions: Dictated by the associated screw thread size.
· Material Properties: Specifications for the mechanical properties (e.g., hardness grade) and chemical composition of steel or stainless steel.
· Tolerances: Governed by DIN EN ISO 4759-3.
· Surface Finish: Often supplied with an 8 µm yellow zinc plating (for steel versions) for corrosion protection.
Compatible Bolts, Screws, and Nuts
The DIN 7989 standard specifies that these thick washers are suitable for use with the following standardized components:
· Standard: DIN7990
· Description: Hexagon head bolts for structural steel bolting, supplied with a nut.
2. Hexagon Fit Bolts
· Standard: DIN 7968
· Description: Hexagon fit bolts for structural steel bolting, supplied with or without a nut.
3. Countersunk Head Screws
· Standard: DIN 7969
· Description: Slotted countersunk head screws for structural steel bolting, supplied with or without a nut.
4. Hexagon Nuts
· Standards:
· DIN EN ISO 4032 (Style 1, Product Grades A and B)
· DIN EN ISO 4034 (Product Grade C)
💡 Application Context
The mentioned products are part of a system for structural steel bolting. An engineering manual confirms that for steel structural assemblies, "black bolts including hex nuts and washers" should conform to both DIN 7989 (washers) and DIN 7990 (bolts). This indicates a common pairing in practice. The washers' large diameter and thickness provide a greater bearing surface to distribute load and prevent damage to the connected material.
📏 Selecting the Right Size
The washer's dimensions are based on the screw thread size (e.g., M10, M22). A product listing for a DIN 7989-2 washer specifies it is "Suitable for screw thread M22". You need to match the washer's nominal size (its inner diameter) to the diameter of the bolt you are using.
If you have a specific bolt size or application in mind, I can help you look for more detailed technical parameters.
💎 In Summary
In essence, DIN 7989 defines a heavy-duty flat washer. It's a critical component for ensuring secure and reliable bolted connections in demanding structural applications by providing enhanced support through its larger dimensions.
I hope this explanation is helpful. If you are interested in specific dimensions or parameters for a particular product grade, I can assist you in finding more detailed information.