GE SoftwarePosted by Deb Frodl, GE ecomagination Global Executive Director on Tue, 2014-11-04 17:17 How Software Is Helping to Save the World | GE Software.
Interchanging and Intermixing Tube Fittings, Part 2 Posted by David Brown on Jul 31, 2014 7:30:00 AM inShare 0 Intermixing Tube Fittings In a previous blog, I wrote about interchanging tube fittings. In this blog, I will discuss a more controversial topic - intermixing tube fitting components. Intermixing stainless steel tube fittings means using the components (body, ferrules or nuts) from one manufacturer with the components from another manufacturing. Some Issues Most manufacturers discourage this practice. Their logic is easy to understand. While most tube fittings seal using the same basic principles, each tube fitting design is unique and each tube fitting components is specifically designed to work with the other components to achieve a seal can increase dramatically. The more dissimilar the design; the more likely it is that they tube fitting will leak or fail. In order to work as designed, the components from one manufacture would have to be identical in geometry and function as the intermixing brand. Even then, it would be advisable to conduct testing to ensure that the tube fitting combinations sealed properly. So why do companies intermix tube fittings. The basic reasons are: Many different tube fittings are available at their facilities. OEM equipment, site built systems, contractor supplies and other sources might increase the number of tube fitting designs in a plant. Installers and maintenance people are not able to tell the difference between tube fittings tube fitting designs. Purchasing may change suppliers and, by extension, change their tube fitting supplier. When maintence orders new fittings to repair a system, they order the current tube fitting carried by their supplier. The current tube fitting vendors carry only one tube fitting design and that design is not compatible original fitting. Done incorrectly, intermixing can lead to leaks, productivity and quality problems. At worst, it can lead to safety and environmental problems. Possible Solutions It seems that the solutions might be straight forward. Maintenance and Purchasing Departments must recognize that they have a variety of tube fitting designs in their facilities and that it is nearly impossible to change this. Purchasing should establish channels to obtain replacement components for each brand. Establishing a mulit-line source for most or all of your tube fitting replacements will reduce handling and inventory costs and stocking issues. Train maintenance and installers on the proper identification and replacement of tube fitting components. Check to see the tube fitting components have been tested to intermix with the current component. Conclusions Intermixing tube fitting presents problems for maintenance and production. The best course of action is to address these situations inadvance by recognizing tube fittng brands and having a source that can supply components that are completely intermixable with the original brand. via Interchanging and Intermixing Tube Fittings, Part 2.
Intermixing Tube Fittings This is the first of a two articles focused on interchanging tube fittings and intermixing tube fitting components. Part one deals with interchanging tube fittings. Part two will take up the issues in intermixing tube fitting components. The Problem Creating leak-tight systems is important to most manufacturing process. The integrity of instrumentation and control systems have significant impact on: Safety and the environment Product quality Productivity and costs When tube fittings leak, it is usually due to improper installation, tubing quality, or product selection. Other times leaks are caused when the components of tube fittings are mixed when making up a fitting. This is called intermixing tube fittings. We will talk about this in my next blog. Interchanging tube fittings is when one tube fitting brand is substituted for another. While this usually happens during maintenance, especially when OEM equipment or original system installation need updates or replacement. It can also occur when an individual maintenance worker or contractor substitutes the brand specified by the system designer with another brand. This usually happens because: The current or specified brand is not available at the time of installation The installer or owner company prefers a different tube fitting brand based on cost and/or experience with the brands. Some Considerations Installers and desigers can be confident when interchanging tube fittings if: They know the replacement brand is a “drop-in” replacement in terms of both size and performance for the current component. Installers are familiar with assembly and installation practices. The fittings have the necessary approvals and meet the performance standards for the application and for material traceability. And Some Guidelines Therefore, when choosing a substitute tube fitting brand, installers and purchasing agents should choose brands that: Are drop-in substitutes for the current brand in terms of size and installation practices. This means that the distance between the points where tubing seats into the tube fitting are identical. Have documented performance demonstrating that the tubei fittings meets or exceed the performance of the current tube fitting brand. Offer documentation and certification that meet material and traceability requirements for the industry and application. Conclusion Designers, installers and OEMs having service issues or are who simply looking for a replacement or backup for their current tube fitting brand can save a lot of engineering and maintenance time, installation problems, and dead inventory by following a few simple guidelines. via Interchanging and Intermixing Tube Fittings.
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Torque tube instrumentation has been a common solution for level control applications. However, many processing plants are converting to a displacer level transmitter, which uses range spring technology, for more reliable level measurement and control. Displacer level transmitters, such as the Magnetrol® E3 Modulevel® linear variable differential transformer (LVDT) transmitter, feature greater output stability, structural integrity and ease of installation, compared to torque tubes. The following outlines why displacer level transmitter technology offers an excellent alternative to existing torque tube units. Principle of Operation E3 MODULEVEL electronic level transmitters are advanced, intrinsically safe, two-wire instruments that utilize a simple buoyancy principle to detect and convert liquid level changes into a stable 4-20 mA output signal. The linkage between the level sensing element and output electronics greatly simplifies mechanical design and construction. Liquid level change acts upon the spring supported displacer causing vertical motion of a core within a linear variable differential transformer (LVDT). The enclosing tube acts as a static isolation barrier between the LVDT and the process media. As the core position changes with liquid level, voltages are induced in the secondary winding of the LVDT. These signals are processed in the electronic circuitry and used to control the current in the 4-20 mA output current loop. Benefits Over Torque Tubes As noted above, reliable output, structural integrity and ease of use are primary reasons displacer level transmitter technology outperforms torque tubes. Range spring technology dampens the effects of vibration and features a longer travel zone, yielding an output signal that is four times more stable than torque tubes. Range spring movement is free of wear and friction, unlike torque tubes, whose twisting motion causes friction buildup and fatigue failure. Displacer level transmitters are easier to install than torque tubes, and don’t require shutdown of process lines. Replacing Existing Torque Tubes I&C technicians who want the benefits of a range spring controller can reduce installation costs by not having to field pipe new cages. The existing torque tube cage may be used, based on the following considerations: Torque tube units should have side/bottom or side/side process piping connections. It is not possible to utilize the existing cage on a top-in/bottom-out torque tube cage. By replacing the entire unit with a complete MODULEVEL device equipped with top-in/bottom-out process piping cage connections, the process piping connection can be matched. If the existing cage has a vent connection piped into the top of the torque tube cage, it will also have to be repiped to a tee. The tee will have to be added to the top process connection on the cage side of the isolation valve or to a vent connection. The displacer length must be the same or shorter than the existing torque tube displacer. Torque tube displacers are larger in diameter than the MODULEVEL and manufactured in the same standard spans. By matching the torque tube chamber parting flange size, pressure, material, bolt circle, and the displacer span, a MODULEVEL unit can be mounted on the existing chamber. via Displacer Level Transmitter Technology Offers Advantages Over Torque Tubes.