AOGV Saves shutdown time of major offshore LNG facility


First Izomax use for Client

Successful deployment, delivered within a critical timeframe

Zero non-productive time


No hot-work

Safety & Utility systems kept operational

First deployment of AOGV in the Asia pacific region

A major customer in Western Australia was planning for a production tie-in on one of the region’s largest offshore LNG facilities. Key to the tie-in was preparation of critical utility systems required for the new production phase, whilst minimising a planned tie-in shutdown.

The Tie-ins involved dismantling a blind flange and installing a valve on three sizes of piping and 3 different systems (DN40, DN50 and DN80).

The facility is one of the region’s largest suppliers of LNG. Bearing in mind the global energy requirements, and current supply issues, any extended production outage was detrimental to the client and their customers.

Critical utility systems such as nitrogen gas, plant air and instrument air are required in any new extensions of oil and gas facilities. Changes or additions to these systems often involve shutting down large parts of the main process systems. When reviewing Izomax proposals and comparing to alternative solutions, the client saw the possibility of reducing the planned shutdown if the tie-ins could be performed while the utility systems were kept operational. A total of 9 tie-ins were required to enable the required extension of the 3 systems.

  • Extended production shutdown required for alternative solutions
  • Tie-in with no hot work
  • Few, if any, alternative solutions available without extending planned shutdown
  • First Izomax project for client


The Izomax patented AOGV is a mechanical isolation tool which can set and retract a blind spade in a pair of flanges on a pressurised process system. The blind spade or a combination of several spades in different locations can facilitate the replacement of valves, and pumps, The AOGV can also be used to take a vessel out of a closed loop temporarily for safe entry and bringing it back on-line. whilst the main process is kept in operation continuously.

Testing, Planning and Preparing

The operation was performed using off-the-shelf stock AOGV mechanical isolation tools. The team that performed system checks and prepared the equipment in the workshop prior to shipping also performed the operation on-site, ensuring continuity from planning, preparation, testing and final job execution.
The design of the AOGV meets or exceeds the requirements of the Pressure Equipment Directive (PED), following the unfired pressure vessel standard EN 13445. The AOGV design is verified by FEM/FEA (Finite Element Analysis) on each individual unit. The AOGV’s conformity to the regulations, directive and standard is assessed by DNV, this includes review of the design calculations report; review of material selection; follow-up of production; welding; material traceability, and proof testing.

Site Operation

Due to multiple personnel working simultaneously in a relatively confined space, the coordination of activities had to be well planned.
The AOGV mechanical isolation system was installed and operated by a team of two trained Izomax technical specialists, based on the established site procedures. The AOGV was suspended throughout the operation, so the plant pipework did not carry any additional loads.
Following installation and leak testing, the flanges were separated using the internal pressure of the line, which separated the flange couple allowing removal of the existing gasket and placement of a spade with integrated seals bolted to the upstream flange.
Following the placement of the AOGV blind, the existing blind flange was replaced by the new flange on the tie-in spool, then the AOGV blind was retracted, and a new gasket was installed. Once the flanges were compressed on the new flange gasket and the joint was verified leak tight, the flange couple was fitted with new bolts and torqued to the client specifications.

The whole operation was completed without any incidents and to the client’s full satisfaction. The Izomax AOGV team executed work on critical systems without interfering with the other activities on the installation. As with all Izomax AOGV mechanical isolation work, no hot work was required, saving the operator considerable time and costs related to planning and executing hot work, in addition to mitigating complex HSSE risk. System integrity was maintained throughout the operation, with plant returned to original status and condition.

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