Misalignment in rotating machinery is a major problem in modern power systems. Giles Goldsbro, founder of Alphatec Engineering, discusses the importance of foundations in the mechanical maintenance process and the benefits of using epoxy grout.
Alphatec has over 35 years of engineering expertise in manufacturing and installing epoxy grout bases for heavy machinery. We operate throughout Europe, the Middle East, Africa, South-East Asia and Japan, and are one of only a handful of other companies that produce and install grout.
Misalignment is our greatest area of expertise; it is by far the most common problem in rotating machines, accounting for approximately 70% of mechanical failures, according to experts in the field. We can usually find the root cause with a simple visual inspection, and can then propose an engineered solution.
Often the grout used for machines is the wrong sort; for example, with cement grouts, oil can leak in and decrease its resistance to the loading of the machine. This affects the anchor bolts, which results in unwanted machine movement that leads to distortions and, eventually, complete misalignment in the machine.
The other major cause of misalignment is that machines do not get the amount of attention they need when they're first installed. Companies often spend a lot of time on the big turbines, but things like pumps, and ID and FD fans get pushed onto the subcontractors - nobody takes much interest in ensuring their foundations are laid correctly.
Misalignment means you've got a rotating shaft that is out of line. Every time it rotates it will flex, and that flexion eventually causes fatigue failure. Worse, it causes the machine to vibrate, resulting in degradation of the grout and damage to the foundation, which will obviously lead to more deterioration; it's a vicious circle.
These sorts of mechanical issues can create significant problems; for example, if a firm has a problem with a boiler water feed pump, that can lead to a turbine being shut down, which is obviously extremely expensive. If the faulty machine is also being used to make something, misalignment can result in faulty products and further loss of revenue.
There isn't really a huge amount of choice. Unless it's possible to carry out mechanical adjustment, regrouting is the only real option. People try and offset misalignment problems by shimming the machine. But for that to work, you need a firm base, and often the only real way to get that is to opt for a regrout. Shimming on concrete is not a long-term solution; within as little as three days, the poor operating conditions will return.
We use a high-quality epoxy grout to attach the machine directly to its foundation, removing shims, wedges, chocks and soleplates, except where they are absolutely necessary, or required by the client or the machine designer. We also pour grout up the side of the machine to provide lateral and longitudinal support.
Alphatec's unique method of high-pressure epoxy resin injection with added reinforcement returns foundations to original, or better, condition, saving a great deal of time and money compared with a rebuild. If a company purchases grout from us and we install it, the material will work properly and their machines will function at optimum capacity for many years, saving them a great deal of money in the long term.
The main advantage of epoxy grout is its longevity. It's got better flexion, tensile and torsion strength than most cement grouts, and has greater resistance to dynamic loading, as well as chemicals, oil and water. The American Petroleum Institute also recommends using an epoxy grout if you're installing a rotating machine on a concrete foundation.
A lot of machine maintenance, such as predictive preservation and vibration monitoring, is still very much aimed at providing a mechanical solution. This will no doubt start to change as people realise there's more to a machine's operating environment than the mechanical layout and base on which it sits. The whole foundation is part of the structure; if that isn't right, you'll inevitably have problems.
