BISEP: Temporary Line Plugging

STATS BISEP® offers pipeline operators an industry leading technology solution for temporary line plugging. Achieved using patented and DNV GL 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.

Hot Tapping & Plugging BISEP
Hot Tapping & Plugging with Bypass, 42
Dual BISEPs with Integrated Bypass
Subsea Hot Tapping & Plugging, 8
Hot Tapping & Plugging, 10
Hot Tapping & Plugging, BISEP with Bypass
Hot Tapping & Plugging, 24
Hot Tapping & Plugging with Bypass, 42

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.

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 back pressure 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 a pressure 50% higher than the isolated pipeline pressure to be applied to the reinstated pipework as a pressure test, 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.

DNV GL Type Approval

STATS inline isolation tool the Tecno Plug® and BISEP® line stop tool are fully certified by DNV GL to verify that the design criteria satisfies the requirements for Pipeline Isolation Plugs to provide dual seal and isolation in accordance with; DNV-OS-F101 (Submarine Pipeline Systems) and recommended Practices; DNV-RP-F113 (Subsea Pipeline Repair) and in compliance with the following code; ASME BPVC Section VIII, Division 2.


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


BISEP DS, Pipeline Hot Tapping & Plugging

Pipeline Hot Tapping & Plugging: BISEP with integrated bypass, USA


BISEP: double block and bleed isolation to reduce risk during pipeline maintenance

BISEP: double block and bleed isolation to reduce risk during pipeline maintenance

This webinar will provide a technical overview of the BISEP functionality and its key benefits to increase safety and reduce costs during planned and emergency repairs and maintenance.

Watch Now

Operator Benefits

  • Fully verified double block and bleed isolation through a single hot tap intervention
  • Leak-tight isolation dramatically increases safety over traditional line stop technologies
  • Isolation remains stable and leak-tight even with significant fluctuating pipeline pressures
  • Single hot tap intervention significantly reduces timescales and costs and also allows installation on short sections of pipework
  • Full compliance with oil and gas industry standard double block and bleed requirements
  • Minimal production disruption on interconnected pipeline networks during valve repairs / tie-ins

BISEP 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
  • Ability to accommodate reinstatement pressure test against the rear of the plugging head
  • 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)


  • Size range: 3”– 54” lines*
  • Pressure range: up to 153 bar / 2220 psi, available in ANSI Class 600 and 900 ratings
  • Maximum operating temperature: 100°C, minimum operating temperature: -20°C
  • Other pressure and temperature combinations available by request
*For sizes 2” and below see STATS BI-STOP™ range