Accurately Measure Process Temperature without a Thermowell or Process Penetration using Rosemount X-well Technology

temperature-surface-sensorUpdate: Download the whitepaper, Achieve Accurate Process Temperature Measurement with Surface Sensor Innovation for more on the Rosemount X-well technology.

Original post: In an earlier post, Online Calculation Tool for Thermowell Installations, we shared ways to avoid resonant frequencies caused by fluid flow around a thermowell inside of process piping.

But what if you could eliminate the need for the thermowell entirely?

Emerson's Ryan Leino


I caught up with Emerson’s Ryan Leino who shared Rosemount X-wellâ„¢ technology, which provides an accurate, repeatable, extrapolated process temperature measurement from a surface measurement. Just imagine being able to measure process temperature with no more leak points, no more process shutdowns due to maintaining thermowells, reduced design complexity which includes wake frequency calculations (WFCs) and more flexibility as project changes occur.

Traditional thermowell installations introduce design complexity, installation expense and require ongoing maintenance. The required pipe penetration introduces a potential leak point and the thermowell is subject to corrosion, abrasion and bending stresses by the fluid flowing around it.

Traditional surface sensors are one way you can go to avoid complexity and design issues associated with thermowells. However, this method gives you the temperature of the surface you are measuring, a value that does not provide an accurate or repeatable representation of an in-pipe process temperature.

The new Rosemount X-well technology removes the challenges of a thermowell assembly while providing a process temperature measurement that a standard surface sensor cannot.

Rosemount-X-well-graph

From the chart, note the green Rosemount X-well line and how closely it tracks the process temperature as ambient temperature changes, especially in relation to the yellow surface temperature. The temperature of the process fluid is measured without the need for a process penetration or thermowell.

This process temperature is calculated via a Rosemount X-well thermal conductivity algorithm in the Rosemount 648 wireless temperature transmitter and Rosemount 0085 pipe clamp and sensor assembly.

Rosemount X-well technology works by measuring the ambient and pipe surface temperatures. These values combined with an understanding of the temperature measurement assembly’s thermal conductivity properties and information of the process pipe material and schedule provide the input for the calculations and extrapolations of the process fluid temperature inside the pipe.

Ryan explained that Rosemount X-well accuracy is a function of ambient and process temperature differential. He shared several scenarios with me where the ambient temperature and the fluid inside the pipe were at various values. When process and ambient temperatures are similar, Rosemount X-well accuracy is approximately that of a traditional thermowell assembly.

As process and ambient temperature diverge, Rosemount X-well accuracy becomes slightly less than that of traditional thermowell accuracy with a total probable error (TPE) less than 1.2% of process temperature reading at its most inaccurate level. Some good applications for the Rosemount X-well technology include:

Rosemount-X-well-assembly

  • Pipeline monitoring
  • Retrofit existing pipes that need new measurement points
  • Pipelines requiring frequent cleaning
  • High velocities
  • Slurries and heavy particulate fluids
  • Clean-In-Place (CIP) processes
  • High viscosity fluids
  • Harsh processes requiring exotic materials
  • Wellhead monitoring

And, unless the temperature measurement is part of a safety loop, custody transfer calculation or control loop, all pipeline temperature measurement applications are good candidates for the Rosemount X-well technology.

Ryan indicated that the Rosemount X-well algorithm is currently available in the Rosemount 648 as a factory assembly with the 0085 pipe-clamp sensor.

You can connect and interact with other temperature measurement experts in the Temperature group in the Emerson Exchange 365 community.

Update: A question came in about measurement delays. Ryan notes that the measurement time response is based on many factors–material of construction, thickness, type of fluid through the pipe, etc. Consult with your Emerson sales team for help with your specific application.

4 comments

  1. Dear Ryan at Emerson,
    Although this technique may work for a particular constant situation whereby all mentioned influences like process fluid heat conductance etc. are constant so the dynamics are stable, how about any process behavior like chemical reactions that may rapidly change ?
    Just like a clamp-on flow measuring device the heat conductance is the main big issue that may result in huge errors that are simply not acceptable for Custody Transfer, although this fully depend on the parties involved but for Fiscal Metering there will be a long way to go before this is “Proven Technology” !
    Anyhow a good start of development like also others are doing research on e.g. reflection spectroscopy with glass fibers along a distillation towers.

  2. Natalie Strehlke says:

    Thanks Dirk for your insights on this new technology. You are correct that Rosemount X-well™ Technology is best suited for use in monitoring applications. For critical control or custody transfer applications, a more traditional solution using a thermowell would most likely be a better fit. That said, Rosemount X-well performance is very much dependent on the application, it’s difficult to talk in generalities about the best applications for the technology.

  3. Both of you are absolutely correct when it comes to measuring accurately and monitoring process temperature. The key points to note here is surface (monitoring only) and process (internal critical). In addition to the physical attributes of temperature change (temperature takes time), we also have to consider installation applications. The surface mounted thermowells as indicated above have a very small application range such that; in Oil & Gas applications, this specific clamp-on solution cannot be used since the application it is meant for does not meet offshore and onshore oil industry engineering specifications for outside pipe applications measuring over 12″ in diameter due to the installation clamps is not only “not approved” to insulation obstruction and pipe corrosion specs but, it also the clamping design does not conform to pipe surface contact specifications and standards. We have tested many of these surface applications out in the field and they do work if the temperature measurement you’re looking for is not critical in nature or accurate for that matter, in the case of freezing alarms the thermowells are fine but, not the mounting application. The main reason for this type of application is for reducing the cost of installation and integration.

  4. Natalie Strehlke says:

    Thanks Kevin for your comments! We have heard these concerns before and are working on a solution that does not require insulation. So stay tuned for more innovation around this technology.

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