3 Effective Ways To Eliminate Pipe Strain
A significant amount of the effort involved in choosing equipment goes into selection and installation. While greater emphasis is now being placed on maintenance to get the best life possible out of your investment, there are some widespread issues that are often overlooked. Pipe strain, for instance, is one of the most common reasons that pumps fail prematurely.
Pipe strain is defined as a 'misalignment between the pump suction and discharge flanges and the corresponding pipe flange connections. Unacceptable pipe strain can be defined as any forces from unanchored piping that will cause equipment deformation of more than .002-in.'**
Pipe strain sometimes occurs while machines are working. This is called dynamic strain. The other type of strain happens regardless of whether your machines are running or not and is called static pipe strain; the most common type typically.
Pipe strain is relatively easy to check and control. Here are three ways to help you get started.
1. Know the cause of your strain
Pipe strain is most often caused by errors at the time of installation, lack of proper support for your pipes, a change in your processes that overlooked piping, or a realignment of things caused by a change in the elements including temperature and pressure. When you suspect pipe strain, first check the supports to see if everything is in place and bolted down. Then think about any recent changes that could be contributing - new valves, machines? Extreme changes in temperature? Obvious signs of movement? Check them all. Identifying your causes and taking effective steps to manage these is your first step to resolution. One of the most effective ways to promote awareness of potential issues is training. A program that covers prevention, the ability to spot a problem should it occur, and a set of protocols to address the problem should be delivered to all maintenance staff.
2. Use established tracking and analysis practices to spot your issues
Often the same contributing factor drives multiple cases of pipe strain. To avoid this, there are best practices followed in the industry. Vibration analysis is one way to gather data that can identify specific installation issues. Another option for static pipe strain is to disconnect the pipe flanges and measure any piping misalignment. Standard practice is a distance of less than 1/64" between the flanges. Dial indicators are mounted at each bearing. Keep an eye on these dials to ensure movement is not greater than 0.002".
Dynamic pipe strain, while harder to spot since it occurs when machines are working, is caused by thermal expansion of piping, weight of fluid and inadequate support. The easiest way to track this is by using a device that measures differences in machine movement while it is working and at rest.
3. Cross check installation to delay future issues
As much as '70% of all pump failures are attributed to misalignment'**. That is an overwhelming majority. One common mistake, for instance, is the use of force. To avoid this, during installation, take steps to ensure no kind of force at all is being used to connect pipes to the pump. The surfaces to be joined must be brought together and the bolts must slide through easily. At the risk of repetition, we must emphasize that all parts that need support must be adequately supported to avoid strain on the pump. Piping must be designed to start at the pump and work its way back, taking into account accurate machinery installation and support requirements to minimize the load on piping.