BISEP Hot Tapping and Plugging

Hot Tapping and Plugging can be achieved using the DNV GL type approved BISEP®. STATS patented BISEP provides fail-safe double block and bleed isolation deployed through a single full bore hot tap penetration, without the need for additional bleed or vent ports. The BISEP offers significant safety advantages over traditional line stop technology, the hydraulically activated dual seals provide leak-tight isolation of live, pressurised pipelines.

This high integrity isolation is provided by a spherical dual seal plug which is deployed from a pressure competent launcher through an isolation valve and rotated towards the flow of pressure to be isolated. The seals are activated by a hydraulic cylinder inside the plug which compresses the seals, the resultant radial expansion pushes the seals out against the pipe bore. Further application of hydraulic pressure generates a rubber pressure in the seal elements which allows the annulus void between the seals to be pressure tested. Each seal is independently tested with full pipeline pressure in the correct direction to verify leak-tight isolation. The seal annulus void is vented to ambient through the BISEP plugging head to provide a zero-energy zone and provides constant monitoring capabilities to prove the seal integrity before and during maintenance, repair, or modification activities.

Line pressure acting against the tool pressure head maintains seal pressure creating a fail-safe feature providing actuation independent of the hydraulic system. The ejection load resistance is provided by the BISEP deployment head.

Dual 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 production.

Once the BISEP is deployed and set in position the pipeline repair or maintenance activities can take place safely and efficiently.

Reinstatement Pressure Testing

The BISEP is designed to resist back pressure so can be used as a test boundary for the reinstatement test. This back pressure is however limited, as the pressure must be retained by the hydraulic set pressure. The BISEP is designed to take 50% of the design pressure as a reverse pressure differential. This is a differential pressure and allows a test pressure 50% higher than the isolated pipeline pressure to be applied to the reinstated pipework as a pressure test, prior to removing the BISEP isolation.

STATS can supply welded split tee fittings or temporary mechanical hot tap clamps along with STATS patented dual seal slab valves and hot tapping services. Once the BISEP is recovered, STATS can provide a completion plug to provide permanent isolation to the branch off-take and enable the removal of the slab valve allowing a blind flange to be fitted.

DNV GL Type Approval

STATS BISEP is 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 Offshore Standards; 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 pipeline repair due to corrosion or mechanical impact
  • Isolate pressure vessels
  • Water or gas injection line isolation
  • Isolation of pipeline end manifolds, pipeline end terminals, subsea manifolds or skids for repair, upgrade or replacement


Hot Tapping & Plugging: Leak-tight Double Block and Bleed Isolation of High Pressure Gas Pipelines

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.

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Operator Benefits

Fully verified Double Block and Bleed isolation through a single hot tap point:

  • Leak-tight isolation dramatically increases safety over traditional line stop technology
  • Single operation significantly reduces timescales and costs. (Single fitting, welding, inspection, scaffolding, crane and excavation costs)
  • Single fitting allows installation on short sections of pipework
  • BISEP technology complies with operator double block and bleed requirements
  • Minimal production disruption on interconnected pipeline networks during valve repairs / tie-ins

Key Features

  • Dual seal annulus void proves and monitors the seal integrity before and during any intervention work
  • Isolation integrity continuously monitored through annulus void, hydraulic set circuit and body vents
  • Seal annulus void provides a Zero-Energy Zone
  • Design provides axial restraint through bearing on dual clevis plates (no single point failure)
  • Dual compression seals are more compliant and have a far higher success rate than traditional cup seals particularly in pitted pipework
  • Self-Energisation of seals maintains isolation integrity independent of hydraulic control circuit
  • No need for additional taps for bleed or vent ports
  • The BISEP can accommodate a 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 conventional equal tee / clamp / branch


  • Size range: 3”– 54”
  • For sizes 2” and below see STATS BI-STOP™ range
  • Pressure range: up to 153 bar
  • DNV GL Type Approval
  • Design allows for deployment into flow conditions (Engineering Assessment Required)