Double Block and Bleed Test / Isolation Plugs

Positively Isolate Explosive Vapors From Hot Work Areas When Performing Modifications and Repairs

  • 3/4″ to 24″ Pipe Sizes
  • Schedule 40, 80 and STD


Double Block & Bleed (DBB) Plug from EST Curtiss Wright Group, revolutionizes isolation and testing of pipe connections. The DBB Plug allows an operator to positively isolate and monitor potentially explosive vapors during “hot work”, then effectively hydrotest the new weld connection with one easy to use tool. The Aluminum/Steel construction makes the tool highly portable, and easy to position. The volume of water required for a test is so small that testing can be accomplished using a hand pump. This greatly facilitates testing in remote areas of the facility.

Double Block and Bleed Plug TEchnical Specification Sheet – Justram.

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After determining pipe and schedule size:

  • Install DBB upstream of “hot work” Area.
  • Expand Seals by tightening compression nut(s).
  • Inject inert gas or water between seals (Isolation Zone) and pressurize.
  • Monitor isolation zone and upstream pressure during “hot work”.
  • After Weld cools release pressure and seal, reposition isolation zone over weld area.
  • Pressurize isolation zone (up to 2,250 psi (155.1Bar)


  • Aluminum/Steel Construction: Plug is portable and easy to position.
  • 1.5:1 Safety Factor: Minimum.
  • Reduces NDE.
  • Low Water Requirements: Uses less than a gallon of water, reducing waste/treatment expense.
  • Quality Assurance System: Manufactured under a Quality Assurance Program certified to ISO 9001 and several U.S. nuclear undustry standards including ANSI N45.2, NQA-11, 10CFR 50 Appendix B, and 10CFR 21.
What is the temperature rating of the Urethane Seals and will the close proximity to heat transfer area compromise the seals during the welding process?

The temperature rating for the Urethane seals is 180°F (82°C). When the plug is installed 12” (305 mm) from the weld, the distance between the weld and the Double Block and Bleed Isolation Plug allows the heat to dissipate and decrease to a temperature that is within the rating of the seals.

Will the Double Block and Bleed Pipe Plug accommodate slight weld intrusion?

The Double Block and Bleed Isolation Plug is designed with increased clearance (up to 3/8” on larger size plugs) to allow the plug to be
positioned over the weld for testing even when slight weld intrusion is present on the Inner Diameter of the pipe.

What is the average amount of time required to install a Double Block and Bleed Isolation Plug and achieve a pressure test?

After the weld area has cooled to an appropriate temperature, the Double Block and Bleed Isolation Plug can be used to complete pressure tests in as little as 10 minutes from insertion to removal.

What upkeep and storage conditions are required to preserve the quality and performance of the Double Block and Bleed Test / Isolation Plug – EST Group Curtiss-Wright?

The Double Block and Bleed Isolation Plug requires periodic inspection of the O-Rings and Seals prior to testing. The compression shafts should be inspected and anti-seize should be applied as needed. After a test has been completed, the compression nuts should be retracted so the seals can fully relax; allowing the Urethane Seals to return to their original size, preventing any permanent swelling and/or deformation.