WIKA TW15 Threaded Thermowell from Solid Bar Stock

Overview

The WIKA TW15 is a series of threaded thermowells machined from solid bar stock in an international heavy-duty design. It screws directly into a threaded process coupling and gives a dial thermometer, resistance thermometer or thermocouple a pressure-tight pocket, so the sensor can be removed for calibration or replacement without opening the line. WIKA lists the chemical industry, process technology and equipment manufacturing as typical areas, for high chemical stress and high process loads, and the WIKA TW15 suits numerous electrical and mechanical WIKA thermometers.

Seven Star LLC supplies the WIKA TW15 to skid fabricators, HVAC and utility contractors, plant maintenance departments and OEMs in Oman and throughout the GCC, with engineering support in Muscat. Threaded wells are the most common thermowell on utility, chilled water and packaged equipment, and we can match them to the thermometers on the same order.

Why a Solid-Drilled Well

WIKA separates protection tubes, made from tubing closed with a welded tip, from thermowells, which are drilled from solid material. The WIKA TW15 is a true thermowell: the bore is drilled into a single bar, and the 6.4 mm tip is integral, with no weld between the stem and the tip. As general engineering background, this gives higher pressure capability and better fatigue resistance than a fabricated tube, which is why bar-stock wells are the default in most oil, gas and chemical specifications.

The stem can be tapered, straight or stepped. As a general guide, a tapered stem offers the best strength-to-response balance, a stepped stem reduces the tip mass for faster response, and a straight stem gives the most material for erosive service. Process limits for the WIKA TW15 depend on the design, dimensions and material, and on process conditions such as flow rate and medium density, so WIKA recommends a wake frequency calculation per ASME PTC 19.3 TW-2016 for flowing lines.

Engineering Design of the WIKA TW15

Three head designs are available: TW15-H with a hexagon, TW15-R with milled wrench flats and TW15-M, a round head with hexagon. Process threads are ½ NPT, ¾ NPT or 1 NPT male, and the thermometer connection is ½ NPT or G ½ female, with bore sizes of 6.6 mm or 8.5 mm, which as a general rule accept 6 mm and 8 mm sensors and stems. The standard connection length H is 45 mm, extendable up to 250 mm where lagging or a cooling distance is required.

Standard insertion lengths U run from 50 mm to 400 mm, or 6 to 16 in, with a one-piece maximum of 800 mm and longer lengths up to 1,575 mm on request. For dial thermometers, WIKA’s formula l1 = U + H − 10 mm for parallel threads, or U + H − 2 mm for tapered threads, gives the correct stem length. Materials include 316/316L, 304/304L, A105, 1.4571, Alloy C4, Alloy C276, Alloy 400, titanium grade 2 and materials per ASTM specifications, with 2.2 test reports or 3.1 inspection certificates available.

Key Features

The WIKA TW15 brings these benefits to threaded temperature points.

• Machined from solid bar stock with an integral 6.4 mm tip and no stem-to-tip weld.
• Three head styles: hexagon, milled wrench flats or round with hexagon.
• Process threads of ½, ¾ or 1 NPT cover the most common instrument couplings.
• Tapered, straight or stepped stems to optimise strength or response time.
• Insertion lengths from 50 mm to 400 mm as standard and up to 800 mm in one piece.
• Wide material choice from 316L and A105 to Alloy C276, Alloy 400 and titanium grade 2.
• Bore sizes of 6.6 or 8.5 mm fit standard WIKA RTDs, thermocouples and dial thermometer stems.
• Optional wake frequency calculation and 2.2 or 3.1 certification for project documentation.

Industrial Applications

Across Oman the WIKA TW15 is installed on chilled water and condenser water headers in district cooling plants, on hot water and steam condensate lines in hospitals and hotels in Muscat, on lube oil and jacket water circuits of gas engines and compressors, on chemical dosing skids at water treatment plants, and on small-bore process lines in the Sohar and Duqm industrial areas. Threaded wells are especially popular on packaged equipment because they install in a standard half-coupling or thredolet.

The WIKA TW15 pairs naturally with a bimetal dial such as the WIKA Model 55 Stainless Steel Bimetal Thermometer, EN 13190, a resistance thermometer like the WIKA TR10 RTD Sensor or a thermocouple like the WIKA TC10-B Thermocouple for Additional Thermowell. For hydrocarbon lines where the client standard requires flanged connections, the flanged WIKA TW10 is the alternative. Seven Star LLC supplies the WIKA TW15 with engineering support, so contractors across Oman and the GCC can order wells and sensors together.

Technical Specifications

The WIKA TW15 values below are taken from WIKA data sheet TW 95.15.

Installation Advice

As general guidance, the tip of the well should reach roughly the central third of the pipe for a reading that reflects the bulk fluid temperature, and on small pipes an elbow or tee installation may be needed to gain insertion length. Use a suitable thread sealant on NPT threads, tighten on the hexagon or flats rather than on the stem, and confirm the thermometer stem length before ordering so the sensor tip touches the bottom of the WIKA TW15 bore for good heat transfer.

How to Order

Ask Seven Star LLC for a quotation on the WIKA TW15 by sending the head design, process thread, thermometer connection, bore, insertion and connection lengths, material and certificate needs. Our Muscat team will confirm availability and lead time, share the WIKA data sheet TW 95.15 and support temperature measurement points for customers across Oman and the GCC.