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To assess an application for AOGV we will review operation data, photos, P&ID and isometric drawings. In some cases, we will need detailed geometry of the flange connection and immediate surroundings.

For complex geometry locations, the site needs to be modeled in our CAD software to ensure no clashes; this can be done by taking accurate measurements or by 3D scanning the location. If 3D scan is used it needs to be of a quality that gives less than 1mm accuracy and high precision, so laser type point cloud scanning will not provide sufficient accuracy to replicate the location in CAD software.

The AOGV needs to be supported at all times by overhead rigging, the flanges need to cleaned and we need access to utilities such as compressed air, leak test medium and connection to applicable drain facilities.

The flange and bolts should be clean from loose particles; it is advisable to replace the bolts and clean the flange bolt holes to avoid delay in the operation. The surface condition required will vary with pressure; a high-pressure gas application will need a better surface finish than a low-pressure water application.

The separation depends on the application, for an application where a blind is to be set the thickness of the blind as a product of the pressure and temperature, typically 80% of the flange bolt diameter.

The AOGV can be designed to accommodate various obstacles on site, but typical space requirements are ½ pipe diameter around the flange and 2x flange diameters in one sector.

That will vary based on the site’s readiness and material handling efficiency, but normally a small AOGV operation like a 2in will take 2 days and a large 18in will take a week.

A small AOGV operation can be executed by a two-man team and a large-size AOGV such as an 18in will require a three-man team.

We need one tool per flange size, the AOGV can leave the blind in place and be moved to subsequent isolation locations.

Yes, the same tool can be used on several
locations.

The AOGV will be designed for one flange geometry.

The AOGV is manufactured and certified in accordance with the European Pressure Equipment Directive (PED). As the original equipment manufacturer, Izomax designs and manufactures the tool to the Unfired Pressure Vessel standard EN 13445 and uses DNV as the Notified Body to fulfil the requirements under PED Module G (unit verification) and issue Certificates of Conformity.

The AOGV will be depressurized and then do a pressure build up test to verify that the blind is leak tight.

The AOGV is designed so the operation can be reversed to rectify any issue. If the leak test is not passed, the leak is addressed and corrected before proceeding.

The blind is verified by leak testing witnessed and signed off by the onsite operator.

Installing an AOGV is a rigging operation that involves the normal risks associated with such an activity. Other risks relate to working on a live, pressurized system and to the handling of process media during draining, venting, and purging. These risks are managed through a job-specific risk assessment, a detailed operating procedure, certified AOGV technicians, and step-by-step verification including verification of the isolation before any downstream work begins.

If process conditions change during the operation, the AOGV can be held at any stage or fully reversed, because it is a mechanical tool that does not rely on the process being stable. The drain, vent, and test ports allow the contents to be drained, depressurized or purged in a controlled way, and the operation is only continued once conditions are understood and confirmed to be within the planned envelope.

The expected process conditions are confirmed with the operator as part of the feasibility review before mobilization. This is also a part of the steps in the procedure on site. If any deviations are discovered, an MoC with help from on call engineering support will be performed to assess the implications.

Double block and bleed (DBB) rely on the sealing integrity of two valves with a bleed between them, so the isolation is only as good as those valves. Where a valve is passing or leaking, which is often the reason the work is needed in the first place, DBB cannot provide a reliable barrier. The AOGV instead sets a physical blind in the flange, creating a positive isolation that does not depend on valve condition. The barrier is leak tested and witnessed before any downstream work begins, so the integrity of the isolation is verified rather than assumed. Failure mechanism of inline isolations such as DBB and plug solutions are also avoided by using a blind.
Link to: https://izomax.com/insights/double-block-bleed-vs-aogv/

The AOGV provides access between the flanges to deploy different mechanisms to remove the gasket, so if the planned solution fails alternative solutions can be deployed.

A sticky or bonded gasket is worked loose mechanically through the access the tool provides. The tool facilitates deployment of several contingencies if needed.

The AOGV has been used on all common gasket types, including RTJ, BX-rings, spiral wound, CFG, CNAF, graphite laminate and CAF.

Yes. The AOGV has a track record across six continents covering a wide range of flange sizes, gasket types and process conditions, and the lessons from these operations feed into the feasibility review and procedure for each new application. Specific reference cases can be shared on request – see our projects page or contact our team.

The condition of the flange faces it assessed indirectly through its ability to seal and the existing gasket, on the blind.

No, the AOGV does not have camera capabilities.

Residual product or sludge at the flange can be drained and flushed through the AOGV drain and purge ports before the new gasket is set. Where heavy deposits are expected, this is allowed in the operating procedure.

The AOGV is designed and modelled to the actual flange geometry, so minor misalignment is accommodated in the tooling. Significant misalignment is identified during the feasibility review and addressed in the operation plan.

The AOGV provides a mechanical isolation that can be held safely in place for as long as needed, so the operation can pause without compromising the barrier. Any schedule impact is managed with the site, but the integrity of the isolation is not affected by the duration.

The operation is reversible at every stage. If an issue arises, the AOGV can be held in position or backed out and the situation rectified before continuing. The barrier is only relied upon once it has been leak tested and verified.

Mobilization time depends on tool availability and site location. Where a suitable tool already exists for the flange geometry, mobilization is driven mainly by logistics and technician availability, typically 4-6 weeks. If a new or modified tool is required, the design, manufacture and certification lead time is added typically 12-24 weeks. We confirm a realistic mobilization date as part of the quotation.

This depends on whether an existing tool fits the application, or a new build is needed, and on shipping to site. For an available standard size, the lead time is largely logistics; for a purpose-built tool the manufacturing and certification time applies. A specific timeline is given with the quote once the application is defined.

Logistics are agreed per project. Izomax prepares and packs the tool, and responsibilities for transport, customs clearance and on-site material handling are usually handled by the client or client-appointed company. Site lifting and rigging support is provided by the client.

Rental terms, including the treatment of transit and standby time, are set out in the commercial agreement and confirmed in the quotation.

The rental terms are defined in the commercial agreement. It is typically based on the time the tool is committed to the project, with the start and end points confirmed in the quotation.

Cost depends on the tool size, the number and complexity of isolations, site conditions, and the rental duration. We provide a quotation once the application has been assessed through the feasibility review.

The AOGV is provided on a rental basis with operation by certified Izomax technicians. Alternative commercial arrangements can be discussed for specific needs.

A tool can be placed on standby or dedicated at a client’s location under a commercial arrangement, for example where a recurring or rapid-response need is expected. This is agreed case by case.

Under the standard rental model, the tool remains the property of Izomax, including the design and intellectual property, whether or not it was purpose-built for the application. Ownership and any alternative arrangement can be discussed as part of the commercial agreement.

Tools cover a wide range of flange sizes, from small bore (around 1 inch) up to large diameters 36 and 48 inch, across multiple pressure classes, and each tool is designed to the specific flange geometry for the application. The current size and pressure-class range can be found online.
Can be found here