A Thermowell is a protective enclosure for Temperature Gauges and Temperature Sensors ( Inserts), which enhance the life of the Inserts from the corrosive and abrasive( harsh) service conditions at the installation point without affecting the performance of the Temperature Sensors or Gauges.
A Thermowell allows the temperature sensor to be removed and replaced without compromising either the ambient region or the process.
Three Major Types of Thermowells.
Using Bar
- Bar Stock Flanged
- Bar Stock Threaded
- Bar Stock Weld In
Using Pipe & Bar
- Fabricated Flanged
- Fabricated Threaded
- Fabricated Weld In
Bar Stock Thermowells are offered for Insertion Lengths up to 600mm as a Standard.
Insertion Lengths can also be provided up to 900mm in Bar Stock if required.
Fabricated Thermowells are generally preferred for Insertion Lengths above 600mm.
Van Stone Type Thermowell
Such Type of Thermowells are used in High Pressure applications, where the presence of any Weld Joints is highly undesirable.
Due to its sturdy and rugged design, these thermowells are highly suited to resist the effects of High Pressure present in the process medium.
These type are machined from a Single Bar Stock, provided with a Collar of suitable thickness, the OD of which corresponds to the RF OD of the Cover or Companion Flange. These thermowells are sandwiched between a Cover Flange and the Nozzle Flange.
Various types of Instrument Connection and Collar OD can be provided as per the requirement.
Solid Sintered Tungsten Carbide Type Thermowell
Such Type of Thermowells are used in highly abrasive environments such as Coal Based Power Plants and Air Preheaters etc.
Solid Sintered Tungsten Carbide has got high resistivity to abrasions due to Coal particles, due to which such type of thermowells are highly preferred mostly in Coal Based applications.
Generally the entire Insertion length comprises of Tungsten Carbide. But in cases where insertion length is very long only Bottom Tail Portion is provided with Tungsten Carbide, which would normally come in contact with the abrasive media.
Sanitary Type Thermowell
These type of Thermowells are generally used to adapt a thermometer or temperature instrument to a Sanitary pipe or tank with a Tri-Clover Clamp connection.
These type of thermowells allows the instruments to be removed for repair, rework or replacement without opening the process connection. These types are specially designed specifically for Food, Dairy and Pharmaceutical Industry.
Lined or Coated Type Thermowell
Such type of thermowells are used in chemically active environments. In these type ,a lining or coating, of a suitable Lining material is done, so as to cover the entire Insertion Length .
The Lining material protects the Base material of the thermowell against the corrosive , chemically inert elements present inside the Process medium. Commonly used Lining materials include PTFE, PFA, PVDF. The Thickness of the lining can be provided as per the requirement.
Sleeved Type Thermowell
Such type of thermowells are also used in chemically active environments. In these type ,a sleeve of the suitable material is made, so as to cover the wetted portion.
The sleeve protects the Base material of the thermowell against the corrosive , chemically inert elements present inside the Process medium. Commonly used Sleeve materials include Hastelloy –C, Nickel, Titanium, Tantalum. The Thickness of the sleeve be provided as per the requirement. Sleeves can only be provided for straight construction.