Process plants around the world depend on millions of rotating machines: compressors, pumps, blowers, fans, presses, generators, mills, mixers, and so on through a long list. The maintenance department is generally pretty busy keeping these machines together, repairing them, and making sure they are available for production.
Mis-alignment causes excessive vibration, increased power consumption, reduced output, and wear and tear on components. But the major cause of mis-alignment – grout failure – is very rarely diagnosed. During the last 35 years or so our group of companies has regrouted and repaired the foundations for thousands of rotating machines in all types of industrial plant.
We are able to restore a machine to a condition which is close to original, or even better in cases where “original” was actually sub-standard.
The basic philosophy behind our approach to foundation repairs is to restore the integrity of the concrete block and to assure that it performs its functions as a vibration damping device – the primary purpose of a foundation. Having identified the cracks and separations, we design a repair procedure to resolve the cause or causes of the cracking, and not merely fill the cracks themselves.
The premises upon which we base our work are:
– The concrete foundation is the main vibration absorbing element of the installation, provided that it is of sufficient mass; that it is one integral whole; and that it is properly connected to the machine.
– The primary cause of a foundation’s inability to attenuate vibrations is the cold joint (see cold joint). Use of an epoxy bonding agent is the only way to obtain full adhesion between pours, and its use is rare. Most foundations therefore have this inherent problem, which can be corrected by Alphatec’s epoxy injection process.
– The best way to ensure that the foundation is correctly connected to the machine is to use epoxy grout, and good anchoring techniques.
– The photo on the right reveals bad installing practices for positioning a baseplate. Shims and other contraptions only worsen grouting adhesion and the transmission of vibrations to the foundation.
– Full-contact grouting is always advised. Soleplate grouting, a second-best approach, stems mainly from the many small failures which are built into a majority of installations, and the necessity to make subsequent modifications and adjustments.
– We drill through the foundation to install epoxy cores with a high-tensile strength steel backbone for the repair.
– The shaft alignment must be as close to “zero-zero” as possible when the machine is operating in its normal condition, not when it is stopped for repairs, adjustment, etc. The question of offsets, both thermal and mechanical, must therefore be addressed before pouring the grout.
Using our hydraulic leveling system (ALPHAPAD®) we can work with the machine in place or even realign it. This technology allows us to repair foundations while machines are still in situ, thereby reducing potentially expensive down-time.
We also take special care of the anchoring bolts, see anchor bolts for further details.
A refurbished foundation where all the cold joints, the polluted concrete and cracks have been addressed, will perform even better than the initial foundation. If the machinery installed on it is properly aligned, grouted with AT800 by a team of experts, and taken care of, there’s no reason why the machine won’t last 50 years or more!