Processing, April 2019

Couplings Fittings T h e s i x s tag e s o f coupler evolution Having grown from the basic threaded connection to next generation dry disconnects chemical processors now have a wide range of choices for their uid handling applications By David Morrow OPW Engineered Systems harmaceuticals soaps and fuels are all products that solve a type of problem for their industries As industries evolved these products have undergone engineered changes to satisfy new process and operational P needs Great product manufacturers constantly strive to improve and develop new products not only to solve industry related problems but also enhance customer experience One industrial product that is an integral cog in the production and supply chain for processes is the coupler As industries have evolved the demands for coupler capability have grown as well Today couplers must ensure uid handling applications meet strict safety and regulatory standards Simultaneously couplers must provide optimized containment of a wide range of uids that can have unique and varying operational conditions Fluid handling operations have continually demanded reliable connections to avoid leaks or spills of high value and or oftentimes hazardous fluids Some of these fluids may often be flammable explosive toxic or even carcinogenic Further in many applications with extreme conditions such as high pressure or temperature connections are required to be more robust Coupler manufacturers saw these demands as opportunities to introduce new and improved designs to the market starting from basic National Pipe Tapered NPT threads to cams and grooves to robust ball valves that minimize spills However over the years the range of options to consider for customers when out tting connections became cumbersome because much research was required before the right coupler could be chosen for the specific fluid handling application e remainder of this article looks at how couplers have evolved in six stages over the years to o er solutions and guide end users on which coupler is a t for their potential application Threads e rst and still most common way to attach a coupler to a hose or pipe is through a threaded connection Speci cally NPT thread remains the standard for all piping and valve threads in the United States Unlike the straight threads found on a typical bolt NPT threads pull together tighter due to the taperedthread design and increased torque is reduces the chance for leak pathways to develop An important operational bene t of NPT threaded couplers is that they are intuitive to connect compared to varying styles of hosing or piping readed connections are optimal for use with low pressure low stress piping and especially in small pipes with diameters of 1 1 2 inches or less The main drawback of a threaded connection is that it will wear out over time if the connection is coupled and uncoupled frequently As a result it must be monitored on a regular basis so that no leak pathways form In addition the connections can be prone to leaks if they are not sealed with Te on tape or another approved sealant In high pressure applications resulting from vibrations or loading threaded connections are less reliable ough the design of threaded connections makes them simple to connect excessive force from using pipe wrenches to tighten them can create safety and ergonomic issues for operators Another point to keep in mind is that while more force usually results in a tighter connection an equal amount of force will be required to undo the connection This can lead to unintentional damage to the coupler followed by leaks and ultimately repair or replacement Flanges Flanges are another type of coupler technology that have found success when used in high pressure uid transfer applications Flanges di er from NPT connections in that they feature two discs that are connected to each other with nuts and bolts with a gasket situated between them The use of this gasket improves seal quality and reliability when compared to a basic threaded connection A properly installed gasket is critical to providing a reliable seal If installed incorrectly the ange will inevitably begin to leak While they offer advantages in sealing capability anged connection systems require more space and are more expensive to install Also because anged systems are heavy to handle and a speci c number of nuts and bolts are required 4 8 16 etc they can be time consuming to connect and may require more operators to install 38 Processing APRIL 2019 Threads All images courtesy of OPW Engineered Systems