The VortexWell® and its Innovative Helical Strakes

At Okazaki we are very proud of our VortexWell® Thermowell. So I thought it would be good to discuss the Helical Strake design we have used and how it works to greatly reduce the formation of Vortices.

Why the VortexWell®?

When fluid flows around a blunt object in it’s path, such as a standard Thermowell, it forms vortices downstream of the object. This is commonly known as Vibration Induced Vortices. The implications of these vortices can have a huge impact, from inaccurate readings to complete failure of the thermowell.

After extensive R&D and independent evaluation, we have developed a unique design of thermowell which we call the VortexWell®. This doesn’t require a velocity collar and is cost effective for the end user in terms of purchase, installation and maintenance costs.

What is the VortexWell®?

The VortexWell® incorporates an innovative helical strake design, very similar to the helical strakes seen on columns and cooling towers. By using the latest CFD software to visualize the flow behaviour, we were able to accurately compare a standard tapered thermowell and the VortexWell®.

In the tests, the standard tapered thermowell showed classic shedding behaviour as expected, whereas the VortexWell® demonstrated no signs of natural flow behaviour. The VortexWell® helical strake design disturbed the flow sufficiently to interrupt the regular formation of vortices. Whilst a small vortex was observed in the wake of the VortexWell® this was a localized stagnation point and didn’t shed.

How the VortexWell® works?

As the vortex shedding frequency approaches the thermowell natural frequency, the tip displacement and stresses are greatly magnified and the thermowell can fail. Even when the thermowell has passed calculations to the ASME PTC 19.3 standard, failures are still known to have happened, Monju Power Plant being a prime example.

To solve this issue, we looked at several different ideas, from increasing damping to streamlined cross sections. It was found that the best solution was to incorporate a helical strake as a vortex suppression method which made our VortexWell the best performing and safest thermowell available.

More information.

If you’d like to learn more about our VortexWell® Thermowell you can view more information here https://www.okazaki-mfg.co.uk/products/sensors/vortexwell-thermowell.

Alternatively, you can all us on 029 2081 4333 or email the team on sales@okazaki-mfg.co.uk.

Recognising the increasing challenges that our clients face, we are proud of the work that our engineers do to bring the latest technological advances to our cabling, heating and temperature measurement solutions. 

Our clients work across the globe in some of the most challenging environments there are and here are a few examples of Solutions we have provided which provide greater stability and more accurate readings.

When it comes to a hydrocracker or hydrotreater unit, our range of specialist multi-point assemblies enable a full 3D temperature profile to be carried out.  We’re also able to offer a unique supply chain solution using our AeroPak mineral insulated cable and laser-welded systems.

An area of particular concern for fluid catalytic cracking units is the harsh operating conditions that they need to work in.  This where our advanced temperature measurement solutions are highly effective.  Clients can choose either our dip-leg or catalyst cooling measurement solutions.  For highly abrasive process conditions, we also have specially coated thermowells that have the ability to operate in such environments.

For the actual catalytic process, we’re fully aware of space being limited, consequently we’ve developed a range of miniature specialist temperature assemblies using our AeroPak mineral insulated cable.  This includes the AeroMini, with an OD of 3mm, it has multiple individual measuring points found on its length.

Other locations where extreme temperatures are also a major factor for consideration include sulphur recovery units.  These are widely recognised for having a harsh process temperature. Our products are frequently chosen due to their ability to ensure the safe and efficient operation of these units.  Storage tanks are certainly another area where there’s great demand for temperature assemblies. 

Cryogenic applications such as LNG storage require an extremely high level of accuracy, and over the years we’ve worked hard to develop the design of our temperature assemblies to meet these demands.  We’re able to supply our RTD or thermocouple assemblies with extended lengths using our patented AeroPak mineral insulated cable.

If you’d like to discuss any of the above or learn about other products contact the team on 029 2081 4333 or sales@okazaki-mfg.co.uk.

At Okazaki, we deal with clients in some of the most demanding industries on the planet – and sometimes beyond! Within the various industries we work within there are numerous challenges that our clients face, and they look to us to help them overcome these challenges.
 

One of the big issues that was faced in the Oil, Gas and Petrochemical industries was the problem of Flow Induced Vibrations around a standard Thermowell, which at best made readings difficult and unreliable, but at worst would result in complete failures and system shutdowns.
 

So, our engineers started at looking into ways we could reduce these vibrations and create a product which would not only be more reliable but also give more accurate results. While researching into possible solutions our team looked through a new guideline which was published by JSME after the failure at the Monju nuclear power plant in Japan. Within this document was mention of several solutions which would prevent the Karman Vortex effect, one of these was the use of ‘Helical Strakes’.
 

Helical Strakes are not an original idea, they had been used for some time in other applications such as industrial cooling towers and car aerials. But it was our own engineers that discovered that this technology would also work on a Thermowell to reduce vibrations. And after testing numerous configurations of strake height, form, pitch, and width we came up with a final solution that along with our Aerodynamic tip provides industry leading results.
 

We call this the VortexWell Thermowell and from its development in 2006 can be found in sites all over the world.
 

But how good is the VortexWell?
 

Well, it has proven through various testing including CFD analysis to be the most reliable and accurate solution by massively reducing the effects of vibration induced vortices and has overcome the risk of Thermowell failures.
 

If you would like to learn more about the VortexWell you can look here (web link) or contact our team on 029 2081 4333 or sales@okazaki-mfg.co.uk.

At Okazaki, we’ve built our reputation on delivering solutions that meet the ever-growing needs of our valued clients. 

And in over 60 years, we’ve continued to develop our solutions using the latest technology.  We know that accuracy and safety are at the top of your agenda which is why, particularly in the case of our Fan Type thermocouples, they’re unique in offering higher reliability than that of competing thermocouples on the market.

The Fan Type has been designed to deliver maximum results for process fired heaters.  We know that failure in your facilities can have a critical effect.  And owing to the exact accuracy required, our thermocouple was designed to deliver meticulous accuracy and reliable temperature measurement capability. 

By installing the Fan Type you’ll also benefit from lower installation costs as the Fan Type removes the need for costly installation engineers.  Its unique design combined with mineral insulated cable also means that you’ll benefit from quality results such as higher levels of accuracy, a reduction of process variability and long life potential – the Fan Type is guaranteed for four years plus.

The clever design of the Fan Type means that it’s the optimum size for attachment to the pipe.  Also, it’s not too large to act as a fin and draw radiant heat into the measuring point; increasing the tube measurement temperature.  Plus there will also be a significant reduction in any heat sink effects and metal dustings in the pipe.

The Fan Type is suitable for an extensive range of heating equipment.  So regardless of whether it’s gas-fired, light fuel or heavy fuel oil burning heaters, you’ll be able to choose a standard Hastelloy-X sheath that meets the individual needs of your requirements.

We also know that when your heater is up and running, the tubes in the furnace have the ability to move and expand between 50 and 350 metres.  Which is why the Fan Type is a far more reliable solution.  It can be adapted easily – both bent and coiled, forming expansion coils.  So you’re able to benefit from compensatory movement in both horizontal and vertical axes.

And not forgetting the safety side, our Fan Type thermocouple meets stringent international approvals.  Plus you can also remain safe in the knowledge that they’re fully certified for use in hazardous environments. 

In April we were pleased to receive certification from Exida to show that our Thermocouples and RTD Temperture Sensors have obtained the level of integrity to meet SIL 3 standards and have been rated to IEC 61508.

All of our products are produced in our state of the art factories and are manufactured to the most stringent standards possible. And we are delighted that this certification along with others we hold proves that our Sensors and Heaters can be trusted for accuracy and reliability in the most demanding environments. 

At Okazaki, we’ve always made it our absolute focus to solve issues that we know our clients constantly face.  So, when it comes to solving thermowell resonance failure issues, we’ve always strived to use the latest technological advances to find the latest solutions.  Which is why since the introduction of the VortexWell thermowell in 1999, our engineers have meticulously developed our solution; ensuring you benefit from market-leading temperature measurement.

A simple and effective solution, we recognise that the industry has been facing several issues when it comes to vortex induced resonance failures.  This is why we’ve continued our extensive research and development to find the most cost-effective and vastly technically advanced product available to you.  We also know that you want to find a solution that easily assesses and calculates potential issues.  The VortexWell meets all of these requirements and more.

Through its clever helical strake design, the VortexWell is able to encounter the issues faced by fluid flowing around a blunt object in its path; forming vortices downstream of the object – also known as vortex shedding.  We’re fully aware of the implications from the vortex shedding frequency or Stroudhal frequency approaching the thermowell natural frequency.  When faced with this situation, the tip displacement and stresses become greatly magnified; causing the thermowell to fail.  We also know that even when the thermowell has passed the ASME PTC 19.3 TW-2010 regulation, failures can still happen.

In considering alternative solutions to solve the original cause of the problem of vortex induced vibration rather than just masking the symptoms, our engineers looked at several ideas including adding a vortex suppression device, avoiding resonance, increasing damping and using a streamlined cross section.

Eventually our engineers discovered that incorporating a helical strake as a vortex suppression method certainly delivers the best performing and safest thermowell solution available.  Through this technique, engineers found that not only the flow disturbance was minimised thanks to its aerodynamic tip, but it also ended the possibility of vortex induced vibration.

If you’re interested in finding out how Okazaki can help you deal with your temperature challenges, contact us on sales@okazaki-mfg.co.uk.

Image 1: Showing flow around a standard Thermowell

Image 2: Showing flow around our VortexWell Thermowell

Out of this World Sensors and Heaters

When it comes to some of the most challenging environments known and even unknown to man, there can be few locations that are as challenging as the moon.  So, when Okazaki was challenged with delivering heaters and sensors for the NASA Mars Curiosity Rover, this certainly presented a worthy proposition.

At Okazaki, we’ve always understood that our valued clients across the globe require extreme levels of product reliability.  We know that time is money, and any impact on production or service can result in serious implications both financially and regarding safety.  We also know that our clients appreciate that world-class quality is our benchmark.

For the purpose of the NASA Mars Curiosity Rover, NASA opted to use Micropak heaters in order to heat the sampling tubes inside the vehicle.  The challenge here was to benefit from greater flexibility when space is particularly paramount. With a small bend radius as a ratio to the outside diameter of heater, the units proved flexible thanks to their ability to be coiled and freely formed into complex and desired shapes.

As part of their investigations, demands on working in an extreme temperature range were certainly met thanks to the operating range of -200 to 500°C which can be achieved by the Micropak heaters.

A further benefit to the project was that the Micropak heater has the same diameter hot and cold sections.  Also, it has no external join which reduces the risk of mechanical joint failure while at the same time as being suitable for being installed in vacuum sealing flanges.

At Okazaki, our engineers and developers are constantly looking to use the latest technical advances to improve the efficiency and safety of our products.  For more info on how our heating and temperature sensors can be used in extreme working environments, please contact Leona Lilford