Conventional flange-to-pipe weld testing often carries with it high costs and risks in the form of downtime and delays, wastewater disposal challenges and potentially dangerous work conditions. Curtiss-Wright EST Group developed its GripTight® Isolation Plug to resolve these challenges and keep workers safer during hot work.
Safe and secure isolation
The GripTight Isolation Plug is a one-tool solution that positively isolates and monitors potentially hazardous and/or explosive vapors upstream of a welding job and effectively hydrotests the new weld connection.
GripTight gripper technology is designed for reliable sealing and adheres to the principle, "The greater the pressure, the greater the grip." If a faulty valve or other event should cause a rapid increase in upstream pressure, the grippers use that pressure to increase their grip on the pipe's ID wall. The grippers hold the GripTight Isolation Plug in place and withstand the full-rated line pressure up to 1,500 psig (103 BarG), thus preventing a failure that could damage the line or lead to serious injury for the on-site work crew.
Testing of a 42-inch GripTight® Isolation Plug.
A two-seal system
The GripTight Isolation Plug is built on the functionality of the proven Double Block and Bleed (DBB) Test Plug. Its dual-port design allows an inert gas or water to be introduced to the cavity section between the two seals through the fill port. At the same time, air is evacuated through the vent port, resulting in a safe, positive pressure barrier between the hot work and any residual upstream gases.
This cavity is pressurized and constantly monitored. Any decrease in cavity pressure, which might indicate a leak, is detected instantaneously. This allows the operator to stop the welding operation and immediately attend to the pressure drop to prevent the possibility of an explosion or fire.
The plug's dual-port system also allows water (or other media) to be circulated between the seals, providing enhanced cooling capabilities during pre-/post-weld procedures. This cooling feature can improve safety for work in areas with tight space restrictions that require the plug to be set in close proximity to the weld area.
Pressure testing
Once welding is complete, the seals are released and the plug can be moved to reposition the isolation cavity over the weld. The plug is then reset and pressurized to test the integrity of the weld, up to a test pressure of 2,250 psig (155 BarG). Pressure tests can be completed in as little as 10 minutes from insertion to removal.
The GripTight Isolation Plug also permits pressure testing with significantly less water than traditional pressure test methods. For example, using a traditional blind flange to test a weld in a 1,000-foot-long, 12-inch Schedule 40 pipe would require filling the entire line with approximately 5,800 gallons of water. Using the GripTight Isolation Plug to test that same weld requires less than a gallon of water. This not only significantly reduces fill time and minimizes the challenges associated with disposing of large volumes of potentially contaminated water, but also helps get the line back into service more quickly.
Availability
The GripTight Isolation Plug is available in a wide size range -- from 3/4 of an inch to 48 inches nominal pipe size (DN20 to DN1200) -- with larger sizes available upon request. The plug's lightweight aluminum and steel construction make it easy to transport and install, oftentimes circumventing the necessity for cranes or other lifting devices, which are typically in high demand.
Curtiss-Wright EST Group can supply GripTight plugs to plants, shipyards and refineries across the Gulf Coast quickly, thanks to a Houston-based distribution network that stocks plugs of various sizes and specifications.
For more information, visit www. cw-estgroup.com/bic0618 or call (215) 721-1100. â¢
