BISEP Line Plugging

STATS BISEP® offers pipeline operators a solution using industry-leading technology for temporary line plugging. Achieved using patented and DNV Type Approved technology, the BISEP provides a fail-safe double block and bleed isolation deployed through a single full bore hot tap intervention, without the need for additional hot tapped bleed or vent ports. The BISEP offers significant safety advantages over traditional line stop technologies, with the hydraulically activated dual seals providing leak-tight isolation of live, pressurised pipelines.

Onshore BISEP Hot Tapping and Plugging Bypass

High integrity isolation

This high integrity isolation is provided by a spherical dual seal plug which is hydraulically deployed into the pipeline from a pressure competent launcher, through a dual seal isolation valve. The seals are hydraulically compressed resulting in radial expansion against the pipe bore. During isolation barrier proving, each seal is tested independently with full pipeline pressure in the direction of the expected pressure differential, proving both seals of the double block isolation are leak-tight. Following successful seal proving, the vented annulus void is then closed and monitored confirming isolation integrity throughout the isolation period.

Find out more about our: Seal Testing & Verification Sequence

Hot Tap installed BISEP with Integrated Bypass, Pipeline Re-Route

The line pressure acting against the BISEP pressure head offers a fail-safe feature by providing actuation independent of the hydraulic system. The ejection load resistance is provided by the BISEP deployment head.

Multiple BISEPs can be used to provide mid-line isolation of pipeline sections and the introduction of a bypass line allows sectional isolation to take place without the need to shut down the entire system or affect product flow.


Reinstatement Pressure Testing

The BISEP is designed to resist backpressure and therefore can also be used as a test boundary for pipeline reinstatement testing. Uniquely the BISEP is designed to take 50% of its design pressure in the reverse direction. This allows pressure higher than the isolated pipeline pressure to be applied to the reinstated pipework (as a pressure test or purge) prior to removing the BISEP.

STATS also supply split tee fittings or mechanical tie-in clamps for hot tap and line stop applications along with its patented dual seal slab valves and SureTap hot tap machines. To allow the BISEP and valve to be recovered completion a plug and blind flange can be provided to isolate the fitting branch off-take.


  • Pipeline launcher valve installation/replacement
  • Pipeline/rise repair, replacement, or decommissioning
  • Pipeline/pipework re-routing
  • Mid-line repair or pipeline defects
  • Isolate pressure vessels
  • Water or gas injection line isolation
  • Isolation of pipeline end manifolds, pipeline end terminals for repair, upgrade, or replacement



3”– 56”


up to 153 bar / 2220 psi


DNV Type Approval


-20°C to 100°C

Key Features

  • Monitored dual seal annulus void proves seal integrity before and during intervention work
  • Isolation integrity continuously monitored through annulus void, hydraulic set circuit and body vents
  • Seal annulus void provides a Zero-Energy Zone (minimal volume x pressure)
  • Design provides axial restraint through bearing on dual clevis plates (no single point failure)
  • Dual compression seals provide higher integrity isolation than traditional cup seals
  • Hydraulically activated seals can be manipulated to improve performance when sealing in pipes with issues such as ovality and internal surface irregularities, ie weld seams, corrosion, erosion
  • Self-Energisation of seals maintains isolation integrity independent of hydraulic control circuit
  • Hydraulic rotation of the plugging head enables BISEP deployment into pipes in any orientation. In addition to horizontal and vertical pipes the BISEP can also operate in pipes inclined from the horizonal making it more versatile than traditional line stop systems.
  • No additional pipeline hot taps required for bleed or vent ports
  • Plugging head designed to take pressure in the reverse direction. This allows pressure higher than the isolated pipeline pressure to be applied to the reinstated pipework (as a pressure test or purge) prior to removing the BISEP.
  • BISEP isolation installed upstream of fitting, maintaining fitting in safe zone during workscope
  • BISEP launcher ported to facilitate venting, purging and flushing of isolated section
  • Can be deployed through a conventional equal tee, clamp or branch
  • Design allows for deployment into flow conditions (Engineering Assessment Required)


BISEP with integrated bypass

48in BISEP Hot Tapping and Line Plugging, USA 2

BISEP with Integrated Bypass

The BISEP can be configured in the Dual Set (DS) configuration which includes an integrated bypass through the launcher, ideally suited to lower pressure applications. The BISEP DS includes many of the benefits of the standard BISEP in addition to the points below:

Key Features

  • The BISEP launcher (housing) includes an integrated bypass which maintains production once the isolation is activated, resulting in no loss of production
  • Double block and bleed isolation through a single fitting with integrated bypass requires fewer fittings and significantly reduces costs and project timescales
  • Pipeline pressure maintains a fail-safe isolation independent of hydraulic activation
  • The BISEP is installed into the pipeline unset allowing deployment into a flowing pipeline, resulting in no interruption to production and saving time on site



3”– 56”


up to 102 bar / 1479 psi


-20°C to 100°C

Related Resources

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Temporary Line Plugging
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