Inflatable Pipe Plugs

Inflatable pipe test plugs are primarily used in applications where time is critical and pipe conditions & geometry are unknown. Inflatable pipe plugs are particularly useful in highly out-of-round pipes and temporary isolation units.

Low Pressure Pipe Plug

The Sealfast® Low-Pressure (LP) inflatable pipe plugs, featuring the double acting seal ring, are available in sizes ranging from 1/2 inch to 144 inches. These easy to install pipe plugs have been used for isolation of piping systems during testing, repair and maintenance, for bypassing of damaged lines, and for isolation of piping systems during construction. The L.P pipe plugs have received wide acceptance in many industrial applications including nuclear and hydro plants, chemical and petrochemical plants, water treatment plants and water and sewer lines.

Medium Pressure Pipe Plug

The Sealfast® Medium-Pressure (MP) pipe plugs, featuring the double ring seal and locking lugs, are available in sizes ranging from 1/2 inches to 144 inches and can withstand pipe pressures up to 100 psig. Applications have included testing, repair and maintenance of piping systems, including the bypass of damaged line sections for continued service.

High Pressure Pipe Plug

The Sealfast® High-Pressure (HP) mechanical plugs are available in sizes ½ inches to 144 inches with a maximum pressure rating of 5000 psig. Test ports allow testing of pipe or tubing through the pipe plug.

Standard Inflatable Plug Series

Standard Tools Restrain and Seal on Pipe I.D. / for Carbon Steel Pipe S40 or thicker
Low pressure – LPI® Series  <25 PSIG Sizes .5″ I.D. thru 144″ I.D.
Medium pressure – MPI® Series <100 PSIG Sizes .5″ I.D. thru 144″ I.D.
High pressure – HPI® Series 100 PSIG to > 5000 PSIG Sizes .5″ I.D. thru 144″ I.D.

Note: Plugs are customized from the standard for different pipe materials & thinner pipe thickness.

How Do Inflatable Pipe Plugs Work?

  • Tighten the restraint screws to center the pipe plug and provide full pressure restraint in the pipe
  • Inflate the inflatable seal to provide a leak-tight seal
  • Fill the test region through the test/fill port, bleed air through the vent port
  • Close the vents and bring the system up to test pressure

H-Frame Inflatable Test Plug Design Concept

The “H” dimension concept is designed into all standard LPI and MPI test plugs 18” and over. The H-Frame style permits the edge-on entry of the plug into the pipe I.D. At this point, it can be rotated to the closure position and installed.

Benefits of the H-Frame Design

  • Allows large diameter MP plugs to be “rolled” as a wheel in the upright position
  • Allows user to navigate bends of up to 90 degrees, providing a reduction in pipe I.D. does not occur

Sealfast® Double-Acting Principle

The Sealfast® Double-Acting Ring Principle embodies a design which produces tensile stress in the outer wall (cross-section) of the uninflated ring while the inner wall is under compressive stress. When the Sealfast® ring is inflated, this built-in stress balance is upset, causing both the inner and outer walls to deflect outward. This forms similar curved configurations without stretching the walls, while sharing equally in radial displacement. Total displacement action and sealing inside the pipe is accomplished with minimum volume of inflation air, which saves considerable effort and time. The Sealfast® Double-Acting Principle embodying thick wall construction of the ring is absolutely essential to withstand the heavy duty service for which the plug is intended, while also improving safety. Contact Us today for standard design literature, product specifications and sizes larger than 144″ for custom design submittals.

Typical Materials of Construction
  • Lightweight structural aluminum plate
  • Stainless and bronze fasteners
  • Can be fabricated from nearly any material, depending upon environmental concerns:
    • Stainless steel (304, 316, Nitronic, 17-4 PH)
    • PVC and other plastics
    • Carbon steel
    • Titanium
    • UHMW
    • Delrin
    • PTFE
    • Cobalt 6B
Typical Sealing Surfaces
  • Carbon steel and stainless steel pipe
  • PVC, HDPE, PVC-lined pipe, Polyethylene, Polypropylene
  • Composites, FRP, Graphite
  • Concrete pipe, RCP, etc.
  • Ductile iron
  • Copper and stainless tubing
  • Hoses
Coatings and Anodic Protection
  • Hard-coat anodized coatings
  • Epoxy coatings
  • Flame spray coatings
  • Zinc and magnesium anodes
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