• Wide Range of Materials
  - Stainless Steels
  - Exotic Materials
  
• Choice of Process Connections
  - Flanged
  - Screwed
  - Weld-In
  
• One Piece Forgings
  
• ASME IX Coded Welding
  
• Special Coatings
  
• Non Destructive Testing

General Description
Solid Drilled Thermowells are precision components manufactured to the highest standard from bar or forgings, to serve as protective devices for primary sensing elements of all types.

A wide range of possible products are available. Conditions of pressure, temperature and corrosion resistance govern the size, shape and selection of materials to ensure optimum dependability system response and accuracy.

Specification

Materials
We are experienced in the manufacture of solid drilled thermowells in a wide range of materials, including 304, 310, 316 and 321 Stainless Steels, 446 Cr-Fe, 6% Mo, Haynes Alloys 214, 230, 556 and HR-160, Carbon Steels, Chromium Steels, Duplex and Super Duplex Stainless Steels, Hastelloy B3, C22, C276 and X, Incoloy 800, 825 and MA- 956, Inconel 600 and 625, Monel 400 and Titanium.

For recommendations on the use of materials, please click here

Instrument Connection
Instrument connections may be male or female, with API, NPT, BSP, or other thread forms.

Process Connection
Connection to the pipe or vessel may be by means of thread, flange or weld.

Threaded Connection
Using standard tapered or parallel pipe threads for simplicity and low cost is popular, generally for low pressure applications.

Standard threads are NPT, BSP(Pl), BSP(Tr) and API. The thread size is dependent on the application, but ¾” and 1” are common.

Flanged Connection
All sizes and pressure ratings are available to DIN, BS, ANSI/ASME and JIS or other standards. Flanged connections are now the petrochemical standard for all applications.

Weld-In Connection
Weld in thermowells are normally used where process pressure and velocities are too great for flanged and threaded, or where long term inexpensive connections are required.

Immersion Profile
The profile should take account of fluid flow characteristics, strength of thermowell and immersion length.

Tip Profile
Consideration should begiven to tip profiles when designing the thermowell for a specific application . As a rough guide, flat tip should be used for lower pressure applications, where flow characteristics around thermowell are not important. Domed and spherical profiles should be used in medium and high pressure applications respectively where flow characteristics around thermowell are important.

Bore
Selected to suit primary sensing element, ensure ease of removal and minimise the amount of free air space around sensor, thus providing optimum response time. In general the outside diameter and bore of the thermowell should be such that the minimum wall thickness is 3 mm.

We operate specialised deep bore gun-drilling machines to ensure the concentricity and finish of the thermowell bore.

Immersion Length
The immersion length should be calculated to ensure that the sensing element has sufficient immersion into the process medium to give accurate measurement. To ensure optimum results and freedom from outside influences, thermowell tip should be located at a point which equates with the lower portion of the centre third of the pipe line.

For tanks, the depth of immersion obviously varies considerably but, as a rule of thumb, 300 mm from outer wall will give ideal results.

In high velocity applications, wake frequency effects must also be considered.

British Rototherm Company Limited,
Kenfig Industrial Estate, Margam,
Port Talbot   SA13 2PW
United Kingdom

Telephone: +44 (0) 1656 740 551
Facsimile: +44 (0) 1656 745 915
E-mail: rototherm@rototherm.co.uk

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