Looking For Thermowells ?

We are one of the leading manufacturers and exporters of Thermowells from India we manufacturer threaded Standard Thermowell, Flanged Thermowell, Socket Thermowells, Sanitary Wells, Van Stone Wells, Weld in Wells in Stainless Steel 304, 316, 304L, 316L, 310, 321 and 446. Additionally we custom manufacturer Thermowell in Inconel 600, Incoloy 800, Nickel, Hastelloy, Brass, Copper, Aluminium or special Alloy metal, we have wide range of standard products to chose from, our standard Thermowell are in stock and ready to ship if you need small quantity, send us your engineering drawing and material specifications one of our Engineer will send you quote immediately.

Our customers are mainly OEM's and Distributors in Europe and USA, we accept blanket orders and can ship in custom packaging with 100% quality inspection which includes ASTM Lab testing reports with each order, for custom small to medium size order we offer quick turnaround time of 2-3 weeks, orders can be shipped via UPS / FEDEX / DHL service to anywhere in the world delivery time is maximum 4-5 working days. We have negotiated special rates with these carriers this makes sense to even import small quantities.

thermowell flangedthermowell
flangethermowell thermo-well
customthermowell ssthermowell


Leg Extn
"T" mm
Process Connection
Inside Bore
DIA mm
Outside Diameter MAX
Length Max
Straight Step Taper
1/2" 6.5 16 16 - 12 16 - 12 300
1/2" 9.5 16 -- -- 300
3/4" 6.5 19 19 - 12 19 - 12 400
3/4" 9.5 19 -- -- 400
1" 6.5 25 25 - 12 25 - 12 600
1" 9.5 25 25 - 16 25 - 16 600
  • Standard Instrument connection (IC): 1/2" NPT/BSP/Metric Threads
  • Longer 'U' lengths offered by BUTT welded multipule sections
  • Other Requirements - please Specify in your drawing


Leg Extn
T mm
Inst Conn
Inside Bore
DIA mm
Outside Diameter
Length Max
Straight Taper
16 MIN
28 MAX
Partial or Full FULL TAPER :600mm
STRAIGHT:1000 mm/
Well Flange
* SS 304, 316, 304L, 316L, 310, 446 * Forged ASTM Gr A182 in SS 304, 316, 304L, 316L, 310, 446
* Inconel 600 or Equivalent * Carbon Steel A105
* INCOLOY 800 or Equivalent * Forged ASTM A182 Gr. F5, F11, F22,LF1
* Nickel * Nickel, Incoloy 600
* Monal or Equivalent * Monal, Incoloy 800
* Titanium * Titanium
* Hastelloy 'B','C' or Equivalent. * Tantalum - Shield
* Ceramic Tube * Other - Please Specify
* Other Specification Please Specify  
Flange Details
PIPE SIZE 1", 1 1/2", 2", 3" NB
150#, 300#, 400 to
600#, 900 to 1500#
Other options available
Well Protection
* COBALT BASE ALLOY, Gr. ST6 or Equivalent
* Tungsten Carbide Coating, PTEE Lined
* Sleeved in Monel, Nickel, Titanium, Tantalum

How to select correct Thermowell

The reason we use Thermowell is because we want to isolate the sensing material to Thermocouple sensors, the reason to isolate could be any to avoid direct high pressure on the Thermocouple material or could be corrosive sate of the material to be tested. Thermowells are made up of different specific metal based on the application material varies from Food industry to use in Oil & Gas industry.

It is very important to select right thermowell for your application one must take Thermal lag which is also called the metal response time, the faster heat conduction of thermowell tube the better would be the sensing accuracy, other technical parameters one should consider is the amount of pressure going to be applied on the thermowell, what temperatures you would need the thermowell to withstand, are you going to use in highly corrosive environment?, the last not least what is the flow velocity of the material being sensed this point is very important in chemical and oil & gas industry.

It is very important to know how you would be mounting the thermowell, is it going to be welded, bolted or you are looking for threaded Thermowell. Selecting material of thermowell is also an important factor we have give list of material recommended for each application based on material temperature to be sensed.

Common Thermowell material used –

  • Carbon Steel ( A105, A350, CF2 ) – Commonly used in oxidizing environments. Its melting point is 2500°F and is used for peak operating temperature is 1300°F

  • 304 SS ( A105, A350, CF2 ) – Widely used for application upto 1650°F This nickel based alloy has good corrosion resistance and can be used in both reducing and oxidizing atmospheres.

  • 316 SS ( A105, A350, CF2 ) – This material can be used for operation temperatures upto  1300°F but the advantage is it has higher corrosion resistance and better creep strength, can be used in both reducing and oxidizing atmospheres.

  • 446 SS ( A105, A350, CF2 ) – Widely used ferrritic stainless steel, ideal maximum operating temperature can be upto 2000°F application condition include reducing oxidizing, vacuum and neutral atmospheres.

  • Brass ( A105, A350, CF2 ) – Used for Food processing industry and temperature upto 550°F

  • Low Carbon Stainless Steel ( A105, A350, CF2 ) – Special quality steel SSi in 304L and 316L ( L = low carbon steel ) operating temperature is similar to SS 304 & SS 316 but the advantage is to reduce the effect of carbide precipitation.

  • Alloy 600 ( A105, A350, CF2 ) – Peak operating temperature for this material is 2100°F, it has excellent corrosion resistance at high elevated temperatures, not recommended in reducing or high sulphur environments.

  • Alloy 800 ( A105, A350, CF2 ) – Operating temperature of is 2100°F the only advantage with Alloy 800 is it has great resistance to sulphur and surface corrosion.

  • Hastelloy B ( A105, A350, CF2 ) – Material can be used for temperatures upto 1500°F in inert atmospheres and 1500°F in highly oxidizing environments, excellent resistance to pitting, stress-corrosion cracking.

  • Hastelloy C ( A105, A350, CF2 ) – Very good corrosion resistance to ferric and cupric chlorides solvents, contaminated mineral acids, wet chlorine gas oxidation resistance to 1800°F and continous service upto 2200°F

  • Monel ( A105, A350, CF2 ) – Strong resistance to sea water and not subject to chloride stress cracking, not recommended for oxidizing atmospheres upper temperature range is 1000°F

  • Nickel ( A105, A350, CF2 ) – Precious metal use in environments highly oxidizing atmospheres, with no sulphur traces, can be used for temperature upper 1400°F

  • Tantalum ( A105, A350, CF2 ) – Upper temperature range is 5000°F widely used as sheath material for stainless steel flanged thermowells, has good resistance to corrosion to most chemicals and a high heat conductivity coefficient.

Mechanical design of Thermowell

This is very important after you have selected appropriate material, the mechanical construction of Thermowell will have to be considered based on the application, below we will discuss some very important consideration.

Connection Type – Generally there are five different types of process connection used in thermowells 1) Threaded, Flanged, Socket Weld, Weld-in and Vance Stone. Threaded wells are widely used in all industry and are made upto 40” length which has NPT type connection. Flanged wells consist of stem welded to an ANSI rated round flange, the weld is commonly referred to as double weld that eliminates crevice corrosion since no open joints are exposed.

Stock weld Thermowell fits ASA standard couplings and flanges, are easy to install and have a very tight fit, weld-in Thermowells are very expensive to install and are used where flanges are not ideal to use. Van Stone Thermowell are one piece construction well installed with a lap joint flange.

Thermowell Length – More than commonly used “U’ Dimension. The immersion length of a Thermowell typically referred as the “U” dimensions and is measured from the bottom of the threads or flange to the tip of the Thermowell. Thermowell which are tip sensitive are less likely to be affected by short “U” length, while RTD’s which are stem sensitive would require longer “U” for the same type of process condition. As a thumb rule engineers consider to immerse a thermocouple at least 3” in gases and 1” in liquids, add 2” to this rule for RTD sensors.

Bore size of Thermowell - Standardization is the key in Process & Automation industry, most of the common bore size used are 0.260” with option of 0.385” upon request, the Bore diameter are common between Thermocouple and RTD sensors.

Well Shank of Thermowell - Strength is key for any Thermowell design. Tappered wells provide greater protection against breaking in high velocity fluid process, higher strength to weight ratio makes tapered the choice over straight Thermowells due to their natural high frequency , reduced tip diameter provides increased sensitivity.

Thermowell & Vibration – This is very important factor one has to consider selecting thermowell, excess pressure, temperature and corrosion are the major causes of Thermowell failure. Vibration, although less common, is significantly more dangerous. A condition called the Von Karman Trail can be caused by fluid flowing by the well which forms a turbulent wake. This wake has a frequency which is based on the diameter of the well and the velocity of the fluid. If this wake frequency is the same as the natural frequency of the well, the resonance could cause the well to vibrate to the extent that the stem fractures and breaks. It is difficult to provide specific information in chart form to assist you in well selection when vibration is a consideration. Maximum allowable velocities will change depending on the “U” length, well material, temperature, type of fluid and well construction. For example a 316SS well with a 3-1/2" U can handle a maximum velocity of 100 feet per second in water at 200°F. The same well in 1000°F superheated steam allows 375 feet per second.

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Our Advantages

  • Compliance with ASTM and ANSI specifications
  • Additional test like Hydrostatic, Dye, Ultrasonic & X-ray offered
  • Custom designed Thermowells as per your drawings
  • Blanket OEM orders accepted
  • We offer Thermowell assembly including RTD
  • Heavy duty design
  • Quick quotes in 24 hours
  • For small orders we can accept Credit card payments
  • Select material as per your specifications

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Transglobe Engineering

F-101 Vraj, Dinesh Mill Road, Baroda - 390007, India Email :

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