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!