Details

A thermowell is a pressure-tight cylinder designed to protect temperature measurement insturmentation from harsh process environments by extending a fitting into the process flow (stream, gas, or liquid). Since thermowells are exposed to some of the most corrosive environments, the design and manufacture of these devices is application specific. During the design stages, factors such as the corrosive agents and temperatures the themowell will be exposed to as well as the mechanical stresses anticipated are taken into account.  From these factors, MPP-USA can assist its clients to select the proper materials and end connections.

 

MPP-USA has the ability to make thermowells in a wide variety of materials, sizes, and end connections, which allows MPP-USA to meet any project requirements.  To this end, MPP-USA maintains an inventory of special allows and exotic metals, such as Titanium®, Hastelloy®-B & C, Incoloy®, 446SS, 410SS, Nickel, Monel®, Alloy® 20, Inconel 600, Teflon®, Aluminum, Duplex SS, F-11, F-22, F-91, and A-105.  Over the years, MPP-USA and its affiliates have developed an engineering, materials, and production database, which ensures MPP-USA's clients the best value in quality, delivery, and service in the industry.

 

Straight Type Reduced Type Tapered Type Fast Response Type

 

Connections:

Threaded Connections:

Threaded wells are made with weld or braze ready materials for installation requiring seal welding or brasing.

The NPT threads provdes mechancial strength, the weld merely acts as a seal.

Flanged Connections (ANSI/ASME and Van Stone):

Flanged wells - except Van Stone type- can consist of a bar stock well, which is is welded to a flange or a well and an integral flange.

Standard weld construction uses a "J" type weld for primary containment and a bevel groove on the secondary weld.  Both welds are then machined to produce a clean fillet.  The double weld construction eliminates any possibility of corrosion and stress problems as no open joints are exposed inside or outside the installation.

Socket Weld:
Socket weld wells are eay to install.  Insert the well in a weld-o-let and weld in place.  Socket weld thermowells are designed to be fitted into ANSI Standard Socket Weld couplings or flanges.

 

Threaded End Connections Flanged End Connections Socket Welds

 

Insertion Length:

The distance from the end of the well to the underside of the thread is designated as U is the insertion length.  The length has be long enough to permit the entire temperature sensitive part of the thermometer bulb to project into the process medium being measured. When installed correctly the thermometer bulb will project into liquid a length equal to the sensing section plus one inch. In gas service the bulb has be immersed this length plus three inches. Thermocouples or thermistors both have short sensing sections, and require minimum insertion lengths. Bi-metal thermometers, resistance thermometers and liquid-in-glass thermometers have bulbs with sensing sections between one and two inches long. For these devices the minimum insertion length is two and one half inches proper accuracy.  Filled system thermometer bulbs may have sensitive portions from one to several inches in length. It is necessary to determine the sensing length of the bulb before choosing an insertion length. In addition to the sensing length you must add in the required length to pass through walls, pipe fittings, insulation, etc when determining the necessary insertion length.

 

Standard Lagging Extention

 

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