Tube Skin Temperature Measurement

Tube Skin Temperature Measurement

Why do we need Tube skin temperature measurements?

To determine accurate temperature data on the surface of the tube
• To withstand corrosive and harsh environment for prolonged period
• To secure weld attachments to the tube wall to fit any tube size
• Fast installation and quick replacement during maintenance period
• To monitor temperature in case of over heating of the tube/ pipe which leads to reduction of the
life period
• To obtain maximum product flow through heat exchanger

What is the Tube skin thermocouple?

The Tube-skin thermocouple features a powerful, reliable, and suitable design to measure the surface
temperature of the most critical, heavy-duty furnaces, heat exchanger, and reactors. Welded directly to the
tube skin (surface), the tip of the tube skin thermocouple provides precise measurement of the surface
temperature of the process tube. Aheat shield is added to prevent the addition of external/ambient gases and
flame temperature on the hot junction, thereby providing more accurate temperature results.

Tube skin Thermocouple Assembly

Expansion loops or coils are designed to avoid the effect of tube expansion which is subject to thermal
growth. Mounting clamps are welded along the pipe to provide additional support. Mineral insulated cable
(sheathed cable) is the flexible part of the sensor. It consists of a metal outer sheath of stainless steels or
Inconel depending on the applications, which contains the insulated conductor wires, compressed within a
high-density magnesium oxide composition.
At one end of the sheathed cable, a non-insulated (grounded or ungrounded) junction, also known as
measuring point (hot junction), is formed by welding the internal conductor together at the center of the weldpad. The measuring point is brought out closer to the tube to provide a faster and accurate measurement of
the tube temperature.

Key Features

• Higher precision can be obtained with the
addition of an optimized shield
• Easy to install
• Reliability combined with fast temperature
response behaviour
• Mineral insulated with flexible sheath cable
• Customizable according to sheath diameter
and sheath materials
• High mechanical strength and shock-resistant
• No special machining of the contact block is
required to match the tube profile.

Application Areas

• Petrochemical and oil industries
• High temperature industries and corrosive
environments
• Boilers, furnaces and ovens
• Gas and chemical industries
• Power plant technology

Technical Specification

Element K, N, E, J
No. of sensors Simplex, Duplex
Hot junction Grounded, Ungrounded
Sheath material Stainless steel, Inconel
Sheath diameter 12.6, 10, 8, 6 etc.
Response Time Less Than 10 sec.
Temperature Range 0-1200°C
Accuracy Class 1, Class 2

Sensor Design

Tempsens provide custom build tube skin thermocouples as per the user requirements and
drawings. Thermocouple assembly consists of different types of pad as illustrated below. Assembly
also consists of an optional ceramic terminal block or head mounted transmitter