Thermowells for Fluid and Gas

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Fluid & Gas Temperature Measurement

EMI are specialist designers and manufacturers of Thermowells for fluid & gas temperature measurement for industrial use. We are proud to be the preferred supplier of specialised Thermowells for BP. The company also has experience specifying alternative temperature monitoring solutions and can source equipment to suit customer requirements. The company has vast experience working with a variety of materials and bespoke designs.

Thermowells for Fluid & Gas Temperature Measurement Tools by EMI Limited
Selection of Thermowells: Flanged Thermowells, Hubbed Thermowells, Welded Thermowells, Weld-in Thermowells
Thermowell Data Sheet

Process Connection:

Flanged, Hub Connector, Screwed, Weld-in, Vanstone,


Solid Barstock, Single Piece Forged, Welded, Fabricated with Solid Tip

Nominal Pipe Sizes:

½” – 4”NB / DN15 – DN100 – Others available on request

Stem Type:

Parallel, Tapered, Stepped

Stem Diameters:

10+ mm

Bore Diameters:

3 mm – 25 mm – Single or Multiple [Single bore 6.6mm most common]


Up to 1200mm overall solid drilled as single piece – Others options available

Instrument Connection:

Male or Female Threads: NPT-F, BSP, Metric Threads

[½”NPT-F Most common]

Material Grades:

Carbon Steel grades

ChromeMoly Steels (F9, F11, F22, F91 etc.)

Austenitic Stainless Steel Grades (300 Series: 316, 304, 310… / 400 Series.)

Duplex/Super Duplex Grades (F51, F53, F55 & F60)

High Moly Stainless Steel (F44 / 6-Mo SS)

Hastelloy (C22 / C276 / B3)

Inconel® Grades (Alloy 600 / Alloy 625 / Alloy 718)

Incoloy® Grades (Alloy 800 / Alloy 825 / Alloy 800H & 800HT)

Monel® (Alloy 400 / 500)

Cupronickel (70/30 & 90/10)

Titanium (Grade 2 – Grade 5)

Tantalum, Zirconium

Material Certification:

EN10204 3.1

EN10204 3.2

NACE – MR0175/ISO 15156 & MR0103 requirements for sour gas applications



Stellite6, Ebonite Lining, Corrosion Resistant Coating. Other available on request


Thermocouples, Platinum Resistance Temperature Detectors (PT100), Bimetallic Sensors. Calibration of sensors available on request


Nipple/Union/Nipple arrangements, Connection Heads, Transmitters


Wake Frequency Calculations to ASME PTC-19.3 (latest version)


ATEX certified assemblies available

  • Carbon Steel grades
  • ChromeMoly Steels (F9, F11, F22, F91 etc.)
  • Austenitic Stainless Steel Grades (300 Series: 316, 304, 310 etc.)
  • Duplex/Super Duplex Grades (F51, F53, F55 & F60)
  • High Moly Stainless Steel (F44)
  • Hastelloy (C22 / C276 / B3)
  • Inconel® Grades (Alloy 600 / Alloy 625 / Alloy 718)
  • Incoloy® Grades (Alloy 800 / Alloy 825)
  • Monel® (Alloy 400)
  • Cupronickel
  • Titanium
  • Tantalum, Zirconium
Thermowells can be designed to suit the following applications:
  • CNC Vertical Machining Centre
  • Many options for materials of construction*
  • 3.1 or 3.2 Materials Traceability & NACE Compliance
  • PTFE/Ebonite/Stellite6 (or equivalent)
  • Cladded
  • ASME, API, PN Rated Process connection to suit all requirements
  • Design Pressures & Temperature to customer requirement
  • Non-Destructive Testing
  • Wake Frequency Calculations to ASME PTC 19.3
  • PED Compliance
Testing available on Thermowells:
  • Hydrostatic Pressure Testing – External & Internal
  • Radiography of Full Penetration Welds
  • Liquid Dye Penetration Testing to PCN Level II
  • Positive Material Identification
  • Ferrite Content Measurement with Ferritescope Tester for Duplex Stainless Steels

Product Samples

Full Thermowell Assembly. Monel® 400 Material (ATEX / Ex d / Ex ia)

Full Thermowell Assembly. Monel® 400 Material
(ATEX / Ex d / Ex ia)

Cross Section of an EMI Thermowell

Single Piece Forged (L) vs Full Penetration Welded (R)

Thermowell Forging Solution by EMI

Single Piece Thermowell Forgings

What Type of Thermowell do I Need?
  • Thermowells we offer:
    • Single Piece forged, Full Penetration Welded, Van Stone
    • Flanged, Threaded, Hub Connector, Weld-in
  • RTDs & Thermocouples
  • Connection Heads
  • Transmitters
  • Accessories
What is a Thermowell?

Thermowells are used when temperature measurement and control is required in a process line or vessel. Thermowells come in many different shapes and sizes. They usually consist of a bar with a blind hole or a capped piece of small bored tube for housing the sensor, a process connection for linking to process pipe or vessel and an instrument connection for connecting a temperature transmitter or terminal block. The temperature sensor is inserted into the blind hole until it touches the thermowell tip on the inside. The thermowell is then fitted to process line or vessel via a standoff or nozzle with matching process connections (e.g. flanged, threaded or welded in). The thermowell will be designed so that the tip protrudes into the process fluid to provide most accurate representation of the fluid temperature for measurement.

Why use a Thermowell?

A thermowell serves as a protective guard for the temperature sensor against damage from the process fluid where fluid pressure, velocity, erosion and corrosion would otherwise cause the sensor to fail. Another major advantage is that the thermowell maintains the pressure boundary allow sensor maintenance or replacement without needing to drain the system.

Thermowell design suitability

In process pipes where the fluid velocity high, the forces acting on the unsupported portion of the thermowell can pose a threat to its integrity and eventually cause failure. Therefore, each thermowell has to be properly designed and optimized to ensure that the thermowell stress level caused by the load doesn’t exceed the temperature-dependent breaking point of the thermowell during operation and/or start-up. Structural damages to the thermowell can be catastrophic and cause the stem to fracture and risk of shearing off into the process line releasing potential explosive, toxic or ecologically harmful substances as well as the injury of subsequent plant sections like turbines, pumps and valves.
EMI use CONVAL software to perform wake frequency calculations. The program calculates critical values for stress and frequency of thermowells in pipelines and compares these values to the allowed limiting values. Temperature dependent values for the maximum allowable working stress, the elasticity modulus and the density are available for many materials. Calculations can be accomplished according to ASME PTC 19.3 respectively DIN 43772:2000-3.

Thermowell Temperature Assembly

Thermowell Temperature Assembly

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Vanstone Thermowell

Vanstone Thermowell by EMI