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Having a tool that can insert and remove an isolation spade on any live flange pair to create a zero-energy zone during inspection, modification and maintenance work can go a long way to increase safety and efficiency while maintaining production.
Developed by IK-Group, the AOGV Mechanical Isolation Tool has been approved and deployed by oil and gas supermajors and multinational NOCs across upstream, downstream, and integrated gas assets.
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Applications include:
- Onsite repair of valves and valve replacement
- Repair and modifications of parts of process facilities
- Retrospective installation of equipment
- Emergency plant and piping repairs
HOW DOES THE AOGV WORK?
The AOGV tool is assembled in sections over any live flange pair, upstream or downstream of the pipework or equipment requiring intervention.
Sealing on the flange circumference and the flange bolt holes, the pipe pressure and inventory is contained within the AOGV housing. The flanges are separated, the gasket removed, and a spade is inserted for isolation purposes.
The AOGV tool is then disassembled and moved to the next location leaving the flange pair and pipework in the same condition as it was post intervention.
POSITIVE ISOLATION
Positive Isolation is regarded as the most secure method for energy isolation and the use of the AOGV facilitates:
- Spool removal: removal of a piped section or spool piece and blanking the live end - also called ‘air gapping.’
- Blind isolation: insertion of a blind between flanges (spade)
Passing valves and leaking flanges challenge any process plant. Built-in isolation points can require partial facility shutdowns and the ejection and flushing of large inventory volumes. Typically, this type of work must wait for – or trigger – a full or partial facility shutdown, leading to significant production loss and increased exposure to risk for personnel.
By bringing the isolation point closer to the point of interest, the AOGV reduces the area impacted by the work thereby negating the likelihood of shutdown and a large ejection of inventory.
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The AOGV is designed to ensure facility downtime is kept to a minimum, asset integrity is maintained, and the risk is mitigated to “as low as reasonably practicable.”
ENVIRONMENTAL IMPACT
The AOGV reduces the isolated area, meaning that more of the process inventory is left in the plant, diminishing the risk of spill and volume of emissions.
- AOGV enables reduced requirement for drainage, venting, purging and flushing
- Reduces volumes to be gas-freed and flared
- Minimizes requirements for storing or transport of drained fluids
- Minimizes disposal of unwanted fluids
- Minimizes release of Volatile Organic Compound to the environment
INCREASES MAINTENANCE FLEXIBILITY
The AOGV can insert an isolation spade at any live flange pair, isolating individual pieces of equipment or sections of the process plant where no other means are provided. This makes it possible to execute inspection, modification and maintenance work, as and when needed, without interruption to production.
The AOGV technology provides quantifiable value by reducing the time spent “in-plant” and the area of the facility impacted. Compared to alternatives, the AOGV allows:
- Isolation of individual parts of equipment where no other means are provided or available
- Execution of work outside of a turnaround (TAR), increasing asset uptime (reliability)
- No requirement for “hot work”
- No permanent alteration to the pipework
- Reduction in maintenance schedule by minimising isolation impact
- Reduction in drainage, venting, purging and flushing time and cost
- Maintained production through simplified isolation
The AOGV is tested to and complies with all relevant regulations and standards – PED2014/68/EU, EN 13445, ASME B31.3, and is CE marked by DNV.
FREQUENTLY ASKED QUESTIONS
1. What temperature and pressure ranges can the AOGV be used?
The temperature range is from - 280 degrees to + 400 degrees Fahrenheit (-173 degrees to +200 degrees Celsius) Pressures up to 2500 psi (175 bar).
2. What sizes of pipe and pressure class combinations can the AOGV be used?
We have been focusing on the ASME class 150 & 300 in sizes 1” to 24” but have tools that can handle sizes up to 36” ASME and up to class 2500. The AOGV can also accommodate other flange standards such as DIN, JIS and Compact Flanges. Please see our tool fleet at AOGV.com for available on-the-shelf sizes and class combinations.
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3. How much clearance does the AOGV need on either side of the flange to be able to be installed?
As a rule of thumb, for pipework from 1” to 4” the AOGV needs 2” of clearance and from 5” and upwards a 1/2 of the pipe diameter is needed. This measured from the bolts and nut side of the flange.
4. How is the AOGV going to seal on the full circumference of the flange and the bolt holes?
The flange seal is pre-energized, acts as a plug, and seals directly from the flange circumference to the inside of the AOGV. The bolt holes are also plugged with mechanical plugs bolted to the AOGV kit. The type of seal used is dependent on the application and process inventory but typically elastomer is used to make sure uneven surfaces will be sealed properly.
5. Can the AOGV be fitted on the flange of a 3-piece valve?
The AOGV can be fitted on most valve types and nozzles including 3-piece valves.
6. Does the pipework have to handle the weight of the AOGV?
For some of the smaller sized AOGV’s, the pipe can easily handle the weight. However, it is normal practice to suspend the weight of the AOGV in chain hoists attached to a super-structure or scaffolding above the AOGV.
7. What about the condition of my flange face?
As part of the AOGV operation, we remove the old seal/gasket at the beginning of the operation and replace it with a new seal/gasket at the end. So far, we have been 100% successful in restoring the flange integrity.
8. How do you perform the splitting of the flanges after the AOGV has been installed?
Either the system pressure is used for splitting the flanges or the pipe is gently moved by use of e.g., chain hoists to pull them apart. The stress tolerances are calculated for the displacements, and we analyze where in the plant you’re able to give a little with your pipe to handle the movement. The movement itself is controlled by gradually releasing the compression exerted by the integrity clamps of the AOGV.
For more information, please contact AOGV Business Development Manager Kenneth Låtveit at kenneth.laatveit@ik-worldwide.com, and to learn more visit AOGV.com.
