What Is a Screw Plug?
A screw plug is a type of plug that is secured into place by screwing. These plugs come in various designs based on the screwing method and whether they include through holes. Common types include hexagonal hole type, hexagonal flange type, and hexagonal flange with a mortise. They are also available in combinations with or without through holes.
The pitch of the screw threads varies, with options like coarse thread for sizes m10 or smaller, and a 1.5 mm pitch for sizes m12 or larger, among other specifications.
Uses of Screw Plugs
Screw plugs are used in various applications, including plugging fluid orifice holes or as mechanical element parts in molding and related fields. They come in a wide range of sizes, from as small as m3 to as large as m48 (with a 2 mm pitch), allowing for selection based on specific needs. These plugs are designed for ease of use, maintaining consistent flange thickness even in larger bore diameters.
Features of Screw Plugs
Screw plugs typically have a large-diameter thread, with nominal diameters ranging from m5 to m18. Materials such as oil cans are often used, necessitating durability, chemical resistance, and airtightness over strength.
Common materials include free-cutting steel like “sum22k” with trivalent chromate treatment. “NBR” nitrile rubber is usually attached as an oil seal to prevent leakage and ensure airtightness.
Screw plugs used in piping often resemble set screws without heads, known as “sunken plugs,” and feature hexagonal holes. These are typically made of austenitic stainless steel, like SUSxm7 (equivalent to SUS304).
While the name ‘screw plug’ is common, the specific types and applications can vary significantly across different fields.