Category: rtd with thermowell

Thermowell Special Coating

Variety of Thermowell Special Coatings

Tests on Thermowell 

Thermowell Material Selection

 

Most industrial facilities rely on some form of temperature measurement in order to monitor and control processes. One of the most critical aspects of temperature measurement is the thermowell. A thermowell is a protective sleeve that houses the temperature sensor. It acts as a barrier between the process and the sensor, allowing the sensor to be removed or replaced without disrupting the process. The thermowell is basically the component that is used to protect sensors from high temperatures. In order to prevent damage to the sensor, a thermowell is often used. This tube-like component is inserted into the process stream. The sensor is placed inside the thermowell. The thermowell protects the sensor from the high temperatures of the process stream. The thermowell also allows the sensor to be removed from the process stream without interrupting the process. Thermowells are often subjected to harsh conditions, which can lead to corrosion and wear. In order to protect the thermowell and extend its lifespan, many facilities specify a special coating for their thermowells.

Thermowell Special Coating

Thermowells are often coated with a special coating to protect the sensor from the high temperatures of the process stream. The coating also allows the sensor to be removed from the process stream without interrupting the process. The coating is applied to the thermowell before the sensor is placed inside the thermowell. The coating is applied to the outside & inside of the thermowell, to the sensor, lead wires, electrical connections, solder joints, terminals, housing, base, cover, mounting bracket, support bracket, gasket, seals, o-rings, washers, screws, and nuts & bolts.

Variety of Thermowell Special Coatings

There are a variety of special coatings that can be applied to thermowells, depending on the specific needs of the application. Some common special coatings include:

• Teflon
• Tungsten
• Boron Nitride
• Zirconia 
• Alumina
• Stellite 

 

The type of special coating that is applied to a thermowell will depend on the specific needs of the application. In many cases, a combination of coatings may be used in order to achieve the desired results. If you are specifying a thermowell for a temperature measurement application, be sure to discuss your coating requirements with your supplier. They will be able to recommend the best coating for your particular application.

Tests on Thermowell 

Some Thermowell tests include the following:

• Radiography
• Material tests
• Dimensional tests
• Dye penetration tests
• Hydrostatic pressure tests

Thermowell Material Selection 

The choice of material is the most significant aspect in the service life of a thermowell. Selection of the thermowell is entirely based on the application temperature & process environment.

• Connection: This happens to be the installation factor
• Insertion Length: This happens to be the accuracy factor
• Bore Size: This happens to be the interchangeability factor
• Tapered/Straight Well: This happens to be the factor for velocity rating 

PTC 19.3 Thermowell Standardization 

ASME (American-Society-of-Mechanical-Engineers) PTC (Performance-Test-Codes) have been made use of for determining the performances of particular, mechanical equipment that tend to be constructed for meeting some required criteria for performance as well as operability. 

Heatcon Sensors

Thermowell Special Coating is a type of coating that is applied to thermowells in order to protect them from the environment and extend their life. There are many different types of thermowell special coatings available, each with its own set of benefits. Choosing the right coating for your thermowell is important in order to get the most out of it. Contact Heatcon for the best range of products in this domain.

 

 

Basic Thermowell Structure – Shank Construction

Flange Face Types

Thermowell Welding

WPS & PQR

 

Thermowell Tip Profile

• Tapered: The outside diameter progressively reduces along the length of the immersion. This is utilized for various high-speed applications. 
• Flat Tip: One end of this is having a flattened surface. This one is utilized for low-pressure applications or in places where the flow characteristics that are around the body aren’t that significant. 
• Domed Tip: This type of protective cover has a hemispherical tip at the thermowell at one of the ends. This one is utilized in various high-pressure applications or in places where the flow characteristics, which are around it, are quite significant. 
• Spherical Tip: For this, a special drill with 118ºC tip angle is utilized for thermowell’s production. The end is spherical i.e. in the shape of a ball, for achieving wall thickness as uniform as possible. 

Basic Thermowell Structure – Shank Construction

• Q-Dimension: This happens to be the shank’s thickest segment on the hotter side of flange or process connection. This depends on the size of the bore & that of the process connection. 
• Bore size: This is Thermowell’s inner diameter. This can also be referred to as the diameter of the cylindrical cavity inside the thermowell or protective tube. The standardized drilling dimensions are 6.5mm and 8.5mm. 
• Immersion U-Length: Thermowell’s length or that of the protecting tube, which is under the flange, the mounting threads, the bushing, etcetera; extending into the area of the process. This length, ‘U,’ is actually measured from the process connection bottom to that of the Thermowell’s tip. 
• Lagging Extension T-Length: Additionally to the standardized head lengths, the trailing extension length is required to allow access to the end of the trailing extension and allow the probe to reach through insulation/walls. 
• Inside Mounting Thread: Thermowell’s inside thread shields to secure the junction temperature device & nipple extension for the assembly of a Thermowell. 

Flange Face Types

• Raised-Face or RF: This is the most commonly used flange type, and this one can be easily identified. This is called an RF or the raised surface as the sealing surfaces are raised above the surface of the bolt circle. 
• Ring-Type Joint or RTJ: Its flanges have grooves, which are cut into the surface that seal with steel rings. 
• Flat Face or FF: This one has a sealing surface that is in the similar plane as the surface of the bolt circle. 

Thermowell Welding 

Welding is actually the process in which 2 metals are joined by heating them to a suitable temperature. This can be made with or without pressure, and with or without any filling. The 2 main types are as under:

• Full Penetration – This particular type of weld provides a fully-welded interface between 2 parts & is usually the sturdiest joint. 
• Partial Penetration – This particular type of weld consists of an interface that is partially welded with a filler metal placed on the surface of the 2 metals.

WPS & PQR 

WPS stands for Welding-Procedure-Specification. It is actually a document, which tends to describe the process of welding and how it should be done in production. These are advisable for all sorts of welding operations as well as the many application codes & standards tend to make them kind of mandatory.  WPQR or PQR is shortened to Procedure-Qualification-Record. This is something that supports the WPS. This is actually a test-weld that has been made & tested (quite rigorously) for ensuring a good weld with the procedure.

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