Proper instrumentation is critical to a plant’s successful production and operation, which makes it very easy to become overwhelmed with all the different options available. The components that make up instrumentation must be monitored and put on a path that best eliminates the possibility of other forces negatively affecting their performance. One area where instrumentation can be improved is during the selection of the most optimal type of fittings. Safety, efficiency, and costs are all determining factors during the selection process, to help choose whether a single- or double-ferrule fitting makes the most sense for a given application.
In all industrial processes, it is important to ensure that equipment is properly installed and maintained to avoid unplanned stoppages. Often, it is the simplest of oversights that can result in expensive downtime, although there are more serious consequences associated with failure, such as blowouts which have the potential to compromise the safety of the workforce. Installation error accounts for a large majority of tube fitting failures, which results in significant cost increases associated to retubing the installation and has the potential for leaks or more serious safety issues. With a double-ferrule fitting design there are over 14 different ways in which the fitting can be made up, of which only 1 is correct. The rear ferrule is the most common cause of installation error and performance issues as it can easily be installed backwards or missing all together, yet still shows as made up correctly when gauging it. Pieces of the double-ferrule system can be small and easily dropped or lost. Single-ferrule fittings have only 2 parts, the nut and ferrule, which is significantly larger and easier to handle than the 2-ferrule design. In addition to that it can only be made up 3 possible ways, 2 of which are easily identifiable as an incorrect make up as shown below.
If the ferrule is missing completely the nut will bottom out on the fitting body, and if the ferrule is in backwards it will not engage the threads, both of which are quickly identifiable problems that will not permit tube make up. Systems will not have to be re-tubed to correct ferrule to body seal integrity issues, thus saving substantial costs in labour and extra materials.
Both single- and double-ferrule instrumentation fittings require lubrication on the nut’s threads to prevent galling. This is an important aspect of the fitting design, but the fittings approach this challenge in two entirely different ways. Double-ferrule fittings use a wax layer with a silver coating, which can melt in a high-temperature environment and becomes ineffective through repeated use. Single-ferrule fittings use a molybdenum disulfide coating, known as moly for short which is used extensively in aerospace applications as a lubricant for stainless steel. It is the most effective anti-gall lubricant available and burnishes itself on to body threads through repeated use, thus extending the life of the fittings. It also does not wear off or degrade in elevated temperatures such as steam, unlike its wax counterpart.
Selecting the most optimum ferrule design for reliable plant operation is a critical step for decision-makers. Spending the time and money to get this piece of the puzzle right has the potential to save plant leaders stress, anxiety, and most importantly revenue. The single-ferrule design simplifies the installation process making it the safer and more reliable choice. Contact us today to discuss how a single-ferrule design can help save you money, while increasing plant safety and reliability.
For your convenience, Viking offers free consultations to assist you and your company in determining your needs. Contact us to discuss how we can help.