THERMOWELLS & ACCESSORIES
Thermowells
• In case the environment is corrosive or harsh, it is recommended that thermocouple / RTD should
be placed in a Thermowell or protection tube.
• These wells can be made from different materials like SS304, SS316, HRS446, Inconel, Monel,
Ceramic, etc.
• The construction can be fabricated or solid drilled bar stock.
Construction of Thermowells
Stepped Shank Also called “reduced tip”. The shank O.D. is reduced over the last 2½” of the “U” dimension from the standard root diameter to ½” O.D. The stepped shank is available with a 0.260” bore diameter only.
Straight Shank Shank O.D. is the same from the root diameter (“Q” dimension) to the tip diameter (“D” dimension). The straight shank is generally used with a 0.385” or larger bore diameter, but is also available with a 0.260” bore.
Tapered Shank Shank O.D. is gradually reduced from the root diameter (“Q” dimension) to the tip diameter (“D” dimension). The tapered shank is recommended for heavy duty applications characterized by high vibration, pressure, temperature, and/or velocity.
Construction of Thermowells
Process Connection External means to connect thermowell to process system. Wells can be threaded, bolted (to matching flange), clamped, or welded in place.
Instrument Connection Internal threads to connect temperature instrument to thermowell.
“U” / "IL" Dimension Length of thermowell immersed into process system. Measured from the base of the process connection to the end tip of the well.
“T” / "EL" Dimension Also called “lag length” or “lagging extension”. Extends length between the instrument and process connections to accommodate vessel or piping insulation.
“S” Dimension Instrument insertion length into thermowell. Equal to bore length.
“D” Dimension Also called “tip diameter”. Diameter of thermowell shank at the end tip of the thermowell. This dimension may vary with process connection and/or shank design as per ASME PTC 19.3
Bore Diameter Dimension of internal bore to match the diameter of the instrument inserted into the thermowell.
Selection Consideration of Thermowells
Insertion Length For best temperature measurement accuracy, the “U” dimension should be long enough to permit the entire temperature-sensitive part of the measuring instrument to project into the medium being measured.Liquid temperature measurement: one inch or greater.Gas temperature measurement: three inches or greater.
Bore Diameter Will depend on inset size, Inset is normally 6/ 8 mm
Thermowell Style Tapered shank wells provide greater stiffness for the same sensitivity. The higher strength to weight ratio gives these wells higher natural frequency than for equivalent straight shank wells, thus permitting operation at higher fluid velocities.
Vibration effect
The calculations necessary to provide adequate strength under given conditions are familiar enough to permit proper choice of wall thickness and material.Less familiar are the vibrational effects to which thermowells are subjected. Fluid flowing past the well forms a turbulent wake (the Von Karman Trail), which has a definite frequency based on the diameter of the well and the velocity of the fluid. The thermowell must have sufficient stiffness so that the wake frequency will never equal the natural frequency of the thermowell itself. If the natural frequency of the well were to coincide with the wake frequency, the well would vibrate to destruction and break off.
Thermowells/Protection TubesMaterial Selection
Material Recommended maximum
temperature
Remarks
Carbon steel 538⁰ C For non corrosive liquid and gases
Cast Iron 700⁰ C For Molten Aluminum
SS 304 870⁰ C Resistant to oxidation and corrosion. Generally used in wet process application such as stem line, oil refineries and chemical solution.
SS316 870⁰ C Good resistance to corrosion applicationSuperior to SS304 in corrosion resistance, resist putting in phosphoric and acetic acids
SS 310 1100⁰ C Superior to SS316, used for high corrosive resistance at elevated temperatures
Inconel 1150⁰ C Excellent mechanical properties and oxidation resistance at high temperatures, used for furnace parts, heat treatments. And heating element sheathings in nuclear engineering. Do not use in Sulphur applications.
Monel 450⁰ C Good resistance to corrosion by sea water sulfuric, Hydrochloric and phosphoric acids. Mostly used in chemical industries
Thermowells/Protection TubesMaterial Selection
Material Recommended maximum
temperature
Remarks
HRS 446 1090⁰ C Excellent resistance to oxidation and corrosion at high temperature, do not use in carbonizing atmospheres.For sulphuric applications, salt bath and molten metals.
Nickle 1090⁰ C Excellent resistance to attack by many chemicals at high temperature. Do not use in sulfur above 538⁰ C
Ceramic tube 60% alumina
1500⁰ C High temperature application, beyond 1200⁰ C to 1400⁰ C. Contaminates the noble metal element on long term.
Ceramic tube 99.7% Allumina
1700⁰ C Gas tight protection, excellent resistance to thermal and mechanical shocks.
Recrystallized Silicon carbide
1600⁰ C Good thermal shock properties, direct flame impregment and abrasion applications.
Facilities
CNC Turning Centers – 13 Nos
Turn Mill center – 1 No.
VMC Machines –1 No.
Deep Hole Drilling Machines up to
1500mm drilling capacity – 17 Nos
Manual Lathe Machines – 60 Nos
Cutting Machines – 8 sets
Machining Facilities
Testing & Calibration
Welding Facilities
Facilities
Laser Welding (YAG) – 2 Numbers
Programmable Micro Plasma
Welding Machines 3 Numbers
TIG Welding machines with pulse
modulation and rotary positioner –
10 Nos
Resistance Welding
Approved and qualified Welders
WPS and PQR for each job
Full penetration welding
Welding Facilities
Machining Facilities
Testing & Calibration
Facilities
Testing & Calibration
Machining Facilities
Welding Facilities
PMI setup for chemical analysis of
Alloys
Pressure test setup
Helium & Nitrogen leak detector
Profile Projector
Dye penetration test setup for weld
joints
Ultrasonic thickness test
Mechanical checks - lengths, gauges,
concentricity checks
Radiography
Thermowells
Material : SS304, SS316, SS316L, SS321, SS310,
HRS446, INCONEL 600/800, 601
Hastalloy, Monel, Titanium etc.
Type : Drilled barstock, Fabricated
Construction : Tapered, Straight
Process Connection : Screwed, Flanged
Certification : IBR certification on request
Thermowell Models
Special Thermowells/Protection Tubes
• Metal Thermowells with Tungsten
carbide/Ceramic/ PTFE/PVDF/PFA coatings.
• Solid sintered tungsten carbide
• Silicon carbide(Re-crystallised & Nitride Bonded)
• Platinum thimble
• Tantalum, Titanium, Nickle cladding,
• Tantalum Tungsten (Ta10W) Alloy
• Graphite
• Silicon Nitride
• Other Materials in various sizes available on
request
Protection Tubes
Material : Re-crystallised Alumina 99.7%
Type : KER 710(C-799) Open Ended, Close
Ended
Length : 350, 530, 600, 650, 740, 900, 1030,
1200, 1430 mm etc.
OD x ID : 6x4, 8x5, 10x6, 12x8, 15x10, 20x15,
24x18mm etc.
Insulating Tubes : 2/4/6 Holes etc.
OD : 1.5, 2.8, 3.5, 5.5, 8.5 etc.
Material : SS304, SS304L, SS310, SS446,
Inconel-800/600,Hastalloy,
Titanium etc.
Type : Open Ended, Close Ended ,Round
Ended Length : As per requirement
Ceramics Stainless Steel Tubes
Quality Test Certificate
Accessories
Material : Die cast aluminium, Stainless steel,
Plastic etc.
Types : A, B, C, DAN, DAN-W, KNE etc.
Single entry, Double entry, miniature
Cable Entry : M24x1.5, M20x1.5, 3/4" ET, 1/2"
NPT/BSP
Bottom Entry : ½” BSP, M20x1.5, 1/2" NPT
Protection Class : IP 65, IP 67, Ex-proof II A/II B, II C
Connection Heads
Terminal Blocks
Material : Ceramic
Terminal : Two, Three , Four, Six, Eight
Accessories
Connectors
• Plug and jack compensated for thermocouples.
• J, K, N, R, S, B, T, E, Types
• Standard, Miniature, Panel mounted, Simplex, Duplex
• Material : Glass Filled Nylon and Ceramic
• Colour Coding : Various Standards
• Lemo Connectors
Compression Fittings
Material
AISI SS316, SS304 ,SS303, Carbon Steel, Brass
Thread
NPT, BS
Accessories
Precision Pipe Fittings
Material
AISI SS316, SS304 ,SS303, Carbon Steel, Brass
Thread
NPT, BS
Seal Pots & Accessories
Material
SS316, SS304, SS303, Carbon Steel, Brass etc.
Thread
NPT, BSP
Accessories
Flanges
Bayonet Caps
Material
AISI SS304,SS316, SS316L,Carbon Steel, Cast Iron etc.
Size
1/2" to 4" & Others
Rating
150# to 2500# etc.
Material
SS316, SS304, SS303, Carbon Steel, Brass etc.
Thread
NPT, BSP
Pyrometer Accessories
Airpurge Unit Adustable mounting (8000-04) Stand
Water cooling Jacket
Packaging & Dispatch
A unique serial number along with material is marked on
each thermowell manufactured by Tempsens.
This unique serial number for each thermowell ensures
vendor accountability for each and every thermowell.
If required, Tag numbers are also marked on it.
Thus, there is 100% full traceability for every thermowell
manufactured in Tempsens.
Special attention is given to deliver the most fragile or the
bulkiest products.
Thermowells first are packed with PVC sleeves to protection
it from Scratching and then these are packed in carton and
the finally in wooden boxes before dispatch.
We ensure that Thermowells are delivered in perfect
condition at the destination.
TEMPSENS INSTRUMENTS (I) PVT. LTD. : UNIT #2A-190, Road No. 5, MIA, Madri
Udaipur - 313 003 (Rajasthan) INDIAPhone : +91-294-3052929/3052953
Fax : +91-294-3052950
Temperature Sensing, Heating & Cables
THANK YOU!
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