Lee 18 mm Short Betaplug

Meet the newest addition to our Short Betaplug product line. The 18 mm Short Betaplug is a pre-assembled, one-piece, tapered expansion plug. This one is specifically engineered to seal fluid passages in metal and plastic housings leak-tight, for life, without the use of threads, sealants or O-rings.

Lee 18 mm Short Betaplug

With this new size plug, Denis de Ploeg continues to expand the breadth of the Short Betaplug product line. The unique, tapered design of the Short Betaplug features controlled expansion during installation that causes the lands and grooves on the O.D. of the plug body to bite into the wall of the fluid passage, creating a leak-tight seal and ensuring retention. The tapered design also eliminates the tight manufacturing tolerances and extra machining necessary with cylindrical expansion devices or threaded plugs, and allows engineers to minimize the wall thickness required around the plug, even for brittle housing materials.

  • Ensures consistent performance
  • Eliminates cracking of brittle materials
  • Facilitates reliable automated or manual installation
  • Reliable seal for life
  • No extra machining necessary

18 mm short betaplug

Cross section - 18 mm Short Betaplug

* LOA before installation.

Maximum passage diameter

Maximum passage diameter - 18 mm Short Betaplug

All dimensions are in millimeters, except where noted.

The Betaplug Advantage

Conventional, cylindrical shaped expansion plugs require additional expansion for the clearance between the plug O.D. and the installation hole.

The matching tapers of the Betaplug and its installation hole create a perfect fit, eliminating the need for additional expansion. Since the Betaplug’s expansion is precisely controlled by the size of the tapered pin, the amount of expansion and any resulting boss stress is completely predictable.

Known Boss Stress - 18/20 mm Short Betaplug
Part Number Performance
PLBA1804610S Rated Pressure*: 35 Bar (500 psi)
Materials: 6061 Aluminium
Maximum Temperature Rating: 135°C (275°F)

* Rated pressures may be higher depending on specific application requirements. Contact your engineer for higher pressure requirements.

Installation hole

The installation hole for the 18 mm Short Betaplug has an included taper angle, Beta, of 4.5°, which matches the tapered outside diameter of the Short Betaplug. This included draft angle of 4.5° is very easy to achieve with a core pin in a die-cast or molded part, or to machine using a tapered tool.

A tolerance of ±0.5° on the taper angle of 4.5° is specified to guarantee that the Short Betaplug’s rated performance is achieved. If the taper angles are out of tolerance, the plug will either wedge first at the top or at the bottom, reducing sealing burst pressure. Tapered reamers are available, see table below for part number.

The Short Betaplug has to be installed below the surface of the housing to ensure optimum performance. The use of coatings or surface treatments in the area of the installation hole where the Short Betaplug is to be installed is not recommended.

Installation Hole - Depth of tapered hole

* Depth of tapered hole from depth of 18.23 minimum diameter.
All dimensions are in millimeters.

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    Betaplug installation

    The installation of these Betaplugs, whether performed manually or automatically, is very easy and economical. First, the pre-assembled Short Betaplug is inserted into the tapered installation hole narrow end first. The pin is then driven into the plug using the recommended installation/staking tool until the pin is below flush and the plug is staked. The installation tool is designed to install the pin below flush while staking over the back edge of the plug (see illustration below).

    The Short Betaplug pin should be installed 0.50 to 0.80 mm (0.020 to 0.031 of an inch) below flush. The installation/staking tool contains a centering feature which ensures proper tool alignment during installation.

    All short beta plug pins are coated with a wax that produces a thin, solid lubricating film that reduces friction, allowing the pin to be driven to its correct position relative to the plug. Do not clean prior to installation.

    The installation force required to drive the pin into the Short Betaplug is a function of boss material, installation hole and boss geometry, and plug size. A boss made of a stronger material or having a larger wall thickness will require a greater installation force than one made of a weaker material or having thinner walls. Typical installation force for A380 die-cast aluminum is shown in the table below.

    Driver - Staker open
    Driver - Staker closed

    Top view of installed short betaplug

    Top view of installed Short Betaplug
    Installation/Staking tool
    Part number
    Tapered reamer
    Part number
    Typical installation
    Force (kN)
    PLBT0160901S PLBT1800012S 8.8 (1980 lbf.)