Navigating the temperature instrument industry for pricing information might be difficult. There is a wide variety of testing and material options for thermowells that will add to cost. Due to the extensive range of tests offered and the wide variety of materials available, these additional costs can equal or exceed the base cost of the thermowell.
Many materials are offered, including Carbon Steel (various grades), 304SS, 316SS, Hastelloy-B, Hastelloy-C, Nickel, Tantalum (sheath) and Titanium.
Additionally, upwards of 20 additional tests are offered, including MTR’s, PMI, Dye Pen, External Hydro Test, External Hydro Test, Ferrite, X-Ray, Ultrasonic and Dye Pen.
Many factors influence the price of instruments such as thermowells, and in my role as engineer and product manager over the past six years, I have pinpointed a few of the key cost drivers that I will detail in this article.
The costs represented in this article depend on the material, the requirements/tests needed, and the process conditions involved.
How Much Do Thermowells Cost?
Here are some general price ranges for various thermowells to give you an idea of pricing:
- Threaded Thermowells: $15 - $500
- Socket Weld/Weld-in: $45 - $600
- Sanitary: $95 - $500
- Flange: $125 - $2,000
- Vortex: $900 - $5,000
If you’re shopping around for thermowells, you should keep these factors in mind when comparing prices to understand the reasoning behind their value.
Top 5 Thermowell Cost Drivers
1. Overall Length of the Thermowell
The length of the thermowell plays a large role in determining its cost. For example, a limited space thermowell with an overall length of 4 inches can be as inexpensive as $30. Quite simply, the shorter the thermowell, the less material required to manufacture.
Conversely, the longer the thermowell, the more material required to make it, which will result in a higher cost. A thermowell with an overall length of 25 inches requires much more raw material, thus a higher cost.
Also adding to the cost, thermowells over 25 inches cannot be machined from solid bar stock. This requires welding the longer thermowells, which adds additional cost.
2. Material Used to Manufacture Thermowells
Ashcroft provides a wide variety of material options for thermowells that will add to cost. Brass, 304SS and 316SS materials are far more common in the manufacture of thermowells. Exotic materials, such as Titanium or Hastelloy-B or C material may be required as it has preferred corrosive properties to certain process media. Such materials are not as readily available from all suppliers and carry a higher raw material cost.
The country of origin of the raw material also plays a large role in the final cost of a thermowell. Materials sourced from vendors located in China or India are more readily available through suppliers, and those cost savings are realized in the final thermowell cost. Due to project or system requirements, it is common for material restrictions to be placed on the country of origin. Material mills in Western Europe or North America may be specified due to the quality of the material. Material such as this is not as readily available and carries a higher cost associated with sourcing.
3. Testing Requirements
Some manufacturers provide a wide variety of testing and material options for thermowells that will add to cost. Due to the extensive range of tests offered, these additional costs can equal or exceed the base cost of the thermowell. Many of these tests may be standard and can be performed in-house; however, some may require a third party due to the specialized requirements.
Wake frequency calculations are perhaps the most common testing requirement and are commonly performed by using a program per ASME PTC19.3 TW-2016 specifications. Other common tests such as hydrostatic testing and dye penetrant inspection (specific to flanged thermowells) can also be performed. However, certain tests may require a third party to complete due to their complexity.
For example, X-Ray and Ultrasonic analysis of flange welds are costly tests that require Ashcroft to use a third-party accredited testing facility. It is not uncommon for a thermowell to require seven or eight different test results based on project requirements.
4. Style of Thermowell
As illustrated in the table below, the style of thermowell also plays a large role in its final cost. There are five different thermowell types:
Threaded: Threaded thermowell process connections are the most common and least costly. Ideal for lower pressures where ½-inch NPT or 1-inch NPT are standards.
Socket Weld/Weld-In: A pipe attachment detail in which the thermowell will be inserted a pipe is inserted into a recessed area of a valve or fitting and welded in place. Socket Weld thermowell fittings are mainly used for small pipe diameters, so sizes 1 inch and smaller are most common.
Sanitary: While a sanitary thermowell also has smaller process connection sizes, it is a bit more costly due to the requirements for use in sanitary applications. Sanitary thermowells have a tri-clamp connection and smooth finish (32 Ra or better) to allow for easy cleaning as not to contaminate the process. There is an additional cost due to manufacturing requirements.
Flange: Piping requirements may necessitate a flanged thermowell attached to piping. In the case of a flanged thermowell, the flange is welded to the solid bar stock shank. The flange material adds additional cost and is subject to the same raw material source and availability described earlier. Flanges come in different styles and carry class ratings of 150, 300, 600, 900, 1500 and 2500. Each has a different rating and thickness based on process pressure and piping requirements.
Vortex: This is the most expensive thermowell style. It’s required for process conditions with extreme pressures and process flow. A vortex thermowell is designed to withstand applications that Standard Flange Thermowells are not to be used by ASME PTC 19.3 TW-2016.
5. Documentation Requirements
A manufacturer may have the thermowells manufactured and ready to ship, but it must now submit documents for shipment approval. All of the completed tests have individual reports that need to be reviewed and approved by the end-user. This may or may not require an onsite inspection to review these documents, stamp and approve. Dimensional drawings may have been required to be customized as well, which adds special dimensions and applicable tagging identification as the project may require.
We don’t like to pressure you, but we have more information.
Now that you have a better idea of price ranges for thermowells and what drives their cost, I hope your shopping becomes easier. You can always reach out to our temperature specialists here at Ashcroft if you have questions or research available thermowells.
To help explore various options available for temperature instruments, our website offers product information pages, white papers, specification sheets, material selection guides, videos, and many other tools.
For more information, explore temperature instruments.
Product Manager Paul Francoletti contributed to this article.