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High Pressure Isolation & Testing Products

GripSafe® ST IIB Inboard Insertion Blocking Isolation & Test Plug

The reverse pressure GripSafe® plug. Pair it with a ported blind flange to test flange welds under the same axial, hoop, and radial loads as a full system hydrotest, or block vessel outlet piping for cleaning and testing, without welding end caps. Back pressure up to 10,000 psi. Sizes 3/4" to 36", to rent or buy. Find your size ›

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GripSafe ST IIB inboard insertion blocking plug family, 3/4 inch to 36 inch

GSST IIB Family, 3/4" to 36"‹›

Medium Size GSST IIB‹›

Small body GripSafe ST IIB plug with extension

Small Body GSST IIB‹›

USA Industries hands-on GripSafe training with an EPC crew

Hands-On EPC Crew Training‹›

Available to Rent or Purchase‹›

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GSST plug model (IIB)
Pipe size and schedule
Flange rating
Test pressure
Quantity needed
Rental or purchase
Date needed

Get A Quick Quote Call (800) 456-8721

Technical Data Sheet

GripSafe® ST IIB

DS-GSST-IIB-001 Rev. Current

Specification	Details
Sizes	3/4" – 36" (larger and custom on request)
Schedules	10 through XXH (see size chart)
Back Pressure Rating	Up to 10,000 psi (varies by size and schedule)
Seals	Tri-Ply® multi-durometer
Gripping	Self-adjusting wedges • Gritlock® surface
Body	Aviation-grade aluminum
Back Pressure Vent	NPT, sized per plug
Temperature	−10°F to 170°F continuous • 200°F intermittent
Body Styles	Small body, 3/4" – 4" • Large body, 4" and up (4" Sch 120, 160, XXH use the small body)
Availability	Rent • Purchase

ASME StandardB16.5

ASME StandardB31.1 / B31.3

ASME StandardPCC-2-2018

The Basics

What Is the GripSafe® ST IIB?

IIB stands for Inboard Insertion Blocking. It is the reverse pressure member of the GripSafe® ST family, built for tests where pressure pushes the plug further into the pipe, such as behind a ported blind flange.

It is also the only plug in the line that does not lock automatically on insertion. Its wedges sit on the far end of the plug, so they hold against pressure from the open end rather than grabbing as the plug goes in. As pressure builds, the wedges grip harder.

Testing open-ended pipe instead? See the GSST ORB. Need double block and bleed? See the GSST DBB.

GripSafe ST IIB family of inboard insertion blocking isolation and test plugs — GSST IIB Family of Isolation & Test Plugs

Applications

Where the IIB Is Used

Flange Weld TestingPaired with a ported blind flange, the IIB puts the weld joint under longitudinal (axial), circumferential (hoop), and radial pressure, the same loads as a hydrotest of the entire piping system. Traditional flange test plugs apply only hoop and radial stress.

Pressure VesselsBlock outlet piping so the vessel can be pressurized for cleaning or testing.

Need flange-only testing? See our Flange Weld Test Plug.

Medium size GripSafe ST IIB inboard insertion blocking plug — Medium Size GSST IIB

GripSafe ST IIB plugs, 3/4 inch to 36 inch — GSST IIB, 3/4" to 36"

Patented Technology

Key Features

Independently Self-Gripping WedgesMounted on the far end of the plug to hold against reverse pressure. Each wedge adjusts on its own to pipe ovality and irregularities, spreading load evenly, and grip increases with test pressure.

Gritlock® Surface TechnologyA brazed texture with thousands of microscopic contact points. Strong grip, minimal marking, and no carbon contamination, so the same plug works in carbon, stainless, and alloy pipe.

Tri-Ply® SealsPatented multi-durometer seals resist deformation and edge mushrooming.

No Sharp EdgesNo serrated jaws or sharp edges, so virtually no surface damage or pipe cleanup.

LightweightAviation-grade aluminum. On average lighter than competing plugs, up to 50% lighter in larger sizes.

Temperature−10°F to 170°F continuous, up to 200°F intermittent.

ReusableProven over hundreds of cycles.

Thin Wall & High Pressure

Pipe Reinforcement Device (PRD)

Some pipe needs extra support at higher back pressures.

RequiredWhen testing A106 Grade B pipe, 4" and larger, at a back pressure above the P-value shown in the size chart.

RecommendedStrongly recommended for all Schedule 10/10S and thinner pipe.

Other MaterialsFor pipe other than A106 Grade B, consult our engineering team.

Proven in the Field

What Crews Say

"GripSafe plugs have been valuable assets on the LNGC site. The quick and easy installation, use, and removal of the plugs have made testing plain end pipe simple. The Lifting Device makes rigging of the larger plugs into position fast, convenient, and safe. The design of the grippers leave little to no marks inside the pipe. Torque values and plug info on the front plate makes plug identification and double-checking for the right plug usage easy. Overall, the GripSafe plugs are an excellent product."
T. Read, Hydro Foreman, and S. Daigle · Global EPC Company

USA Industries hands-on GripSafe plug training with an EPC crew — Hands-On Training with an EPC Crew

Pressure Testing Solutions

Test Plugs vs. Welding End Caps

GSST Test PlugsWelded End Caps

SpeedInstalls in minutes, ready to test right awayWeld, cool, test, then grind off. Hours per cycle

CostReusable. No welders, consumables, grinding, or NDESingle-use caps, welder labor, consumables, and inspections

SafetyNo hot work permits, arc flash, fumes, or burnsOpen flame and hot metal. Permits, fire watch, and PPE required

FlexibilityReposition and reuse across spools and test setupsPermanently welded. Changes mean cutting off and starting over

Pipe QualityNo heat-affected zone. Low risk of contamination or distortionHeat-affected zones, possible distortion, post-weld NDE

The Bottom LineIsolation and test plugs transform pressure testing from a bottleneck into a streamlined operation, delivering speed, savings, safety, and flexibility that welding end caps simply cannot match.

Critical Safety ReminderPressure testing is hazardous. Make sure all connections, valves, flanges, and fittings are suitable for the test, and verify the line ID falls within the plug's range. Never stand in front of a test plug or enclosure during testing; a discharge can cause severe injury or death. Follow the full installation procedure in the operating manual, and never exceed the rating of the lowest rated component in the system.

Available to Rent or Buy

Rent GripSafe® for Your Next Turnaround

Rent the plugs you need for the job instead of buying and storing a full set, with our team on call 24/7/365.

Lower Upfront CostPay for the job, not the inventory

No StorageWe keep them between jobs

On Call 24/7/365Support whenever the job needs it

Get A Quick Quote See Rentals

Common Questions

GripSafe® ST IIB FAQ

What is the difference between the IIB and the ORB?

The IIB is built for reverse pressure, where the test pressure pushes the plug further into the pipe, as it does behind a ported blind flange. For testing open-ended pipe, use the GSST ORB.

How is it better than a traditional flange test plug?

Paired with a ported blind flange, the IIB tests the weld under axial, hoop, and radial pressure, matching a full system hydrotest. Traditional flange test plugs apply only hoop and radial stress.

How much pressure can the IIB hold?

Up to 10,000 psi on smaller sizes. The rating varies by size and schedule, so check the size chart for your plug. Never exceed the rating of the lowest rated component in the system.

When do I need a Pipe Reinforcement Device?

In A106 Grade B pipe, 4" and larger, when the back pressure will exceed the P-value in the size chart. It's strongly recommended for all Schedule 10/10S and thinner pipe. For other materials, consult our engineering team.

How do I choose the right plug?

Start with pipe size and schedule in the size chart, then confirm the measured pipe ID falls within the plug's recommended ID range. On 6" through 24", the tool OD must be within 1/8" concentricity to the pipe ID. Not sure? Call us and we'll match it for you.

Do you make sizes larger than 36"?

Yes. Larger sizes and custom configurations are available on request.

Can I rent IIB plugs?

Yes, rent or purchase. See rentals.

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