GUIDE ON HOW TO
GROUT ROTATING EQUIPMENT
Techmar has established a step by step guide to show best practices for optimum equipment performance with machinery grout. The goal is to set equipment with epoxy grout creating a monolithic structure between the foundation and the piece of rotating equipment. This monolithic structure (created by the epoxy grout) is an effective means to transfer the vibration from the equipment to the foundation, resulting in an overall increase of reliability of the equipment. If you have any questions please do not hesitate to contact us at firstname.lastname@example.org.
Step 1: Concrete Foundation
A piece of rotating equipment needs a properly sized foundation (mass) to support the equipment and dissipate vibration. The foundation should be sized three times the equipment weight for a rotating piece of equipment. Similarly, the foundation should be sized five times the weight for a reciprocating piece of equipment. This is normally achieved by pouring the mass out of concrete. The concrete needs to be completely hydrated before moving to the next step. This occurs approximately 28 days after the concrete is poured. If you don’t have 28 days, a high early concrete mixture can be poured, requiring 7 to 10 days for proper concrete hydration. If you need an even faster turnaround on your foundation the concrete can be dosed with Gill-33 which can achieve “28-day hydrated concrete” in one day.
Step 2: Prepared Concrete
Now that our concrete foundation is completely hydrated, the surface needs to be prepared. The preparation of the surface is to remove the laitance layer of concrete. This layer is approximately the top 3/8” to 3/4” of the concrete foundation. The laitance layer is the weakest part of the concrete, typically a few hundred psi in compression. API requires that at least 1” of concrete be removed in preparation for epoxy grout. This can be achieved by using a 30-pound chipping hammer to remove the laitance layer, exposing broken aggregate. The profile of the surface should have approximately a 1” difference between peaks and valleys creating more surface area for the epoxy grout to bond with the strongest part of the concrete. When chipping the foundation, you should chamfer the corners of the foundation and round the edges to avoid any sharp corners.
If your prepared surface extends greater than 6” past the foot print of the base you may want to consider pinning the perimeter of the foundation surface to prevent edge lifting. If your base plate is larger than 5' to 7' in any direction you may want to consider installing expansion joints. Click on the learn more for further details.
Step 3: Anchor Bolt
The anchor bolt is the main hold down of the equipment. In our illustration, the anchor bolts were poured into the foundation and there is a sleeve around the anchor bolt. This sleeve is installed to allow for proper stretch of the anchor bolt. The stretch length should be approximately 8 to 10 times the bolt diameter. More details can be found on our anchor bolt FAQ page. To allow for proper bolt stretch, the space between the pipe sleeve and the anchor bolt needs to be filled with a non-binding material. A non-binding material will prevent the grout from entering the sleeve and bonding to the anchor bolt. A good example would be to fill this area with an expanding spray foam level to the surface of the prepared foundation.
Step 4: Bolt/Leveling
Prior to setting the base plate, the exposed threads of the anchor bolt need to be protected from grout contact, thus allowing for stretch. One method of protecting anchor bolts from grout contact is to place foam pipe insulation over the threads. This can be done before or after the base plate is set. Next to each anchor bolt a flat surface is required to set the leveling bolts and provide a temporary means to support the piece of equipment. This is generally a piece of 2” round stock with all edges radius eliminating sharp corners. This leveling pad needs to be affixed to the prepared foundation. This can be set using an epoxy putty, Phillybond #6. With your anchor bolts protected and leveling pads in place, you are ready to set the base.
Step 5: Base Plate Setting
The foundation is ready to have the base plate set. Base preparation should be done to ensure the base is clean and ready for epoxy grout installation. Please see base plate preparations. The base can be landed on the foundation and set to your precise leveling tolerances. The base is supported on the leveling screws next to each anchor bolt. If your base does not have a leveling device installed, you will need to install them on the base. A hex nut welded to the top of a steel base plate works well for the installation of a jack (leveling) bolt. A base plate should never be set or supported by the anchor bolts on jam nuts, this prevents the “free” stretch length of the anchor bolts, limiting their ability to properly anchor the base. Once the base is level a small torque should be applied to the anchor bolts to hold the base in place during the grouting process. Make sure the anchor bolts are completely sealed between the foundation and the bottom of the base plate as to not allow grout to contact the threads. If pipe insulation is not available, several wraps of duct tape will work. The jack bolts (leveling screws) will need to be coated with a releasing agent, grease or never seize, to the threads allowing for their removal after the grout has cured. Please use caution when applying a release agent to the leveling device as to not coat the underside of the base plate or contaminate the concrete.
Step 6: Form Work
Now that your base is set you are ready to install the grout forms. The forms should be installed approximately 2 to 4 inches from the edge of the base plate. The forms should be constructed of sturdy material. It is recommended to use at least a two-by dimensional lumber. The forms should have several coats of a paste wax to allow for the grout release after it has cured. The forms should have 1 inch chamfer strips installed horizontally at the top of the bottom base flange. This level will aid to ensure contact is made with the base plate on the lock-in pour. A vertical chamfer should be installed in the corners of the form not to allow for sharp edges when the grout has cured. Please see the detail on the sketch. The forms must be constructed for either a one or two pour method. Be sure the forms are water tight. This means the formwork should be caulked to the base to ensure the grout does not leak. Silicone sealant works well for sealing forms.
Step 7: Lock-N Pour
Mixing per manufacturer’s instructions, please see our page on mixing of grout. Once the grout is properly mixed it is ready to be placed. Care should be taken to pour the material in one direction ensuring contact with the bottom of the frame rail. In this illustration, the material should be poured inside the frame and the material will be pushed to the outside forms. You do not want to pour from both sides of a frame rail as the material is not capable of relieving trapped air. If there is trapped air, this will result in a void or insufficient support of the equipment. Once the material has made full contact with the bottom of the frame rails, make sure that your forms are not leaking. If a leak is found it must be plugged or stopped immediately.
Step 8: Cavity Fill
Your lock in pour was successfully completed and sufficient curing time has passed (approximately 24 hours depending on temperatures). The next step is to fill the cavity of the pump with grout. If you are wondering why to fill a cavity, that can be answered here. When the second lift or cavity fill is done, the material will chemically bond to itself creating a monolithic structure required to effectively transmit vibrations from the piece of equipment. We want to ensure full contact with the entire base and need to fill each cavity and maintain hydraulic head pressure after we are full. This can be done with a head box, funnel, or even a traffic cone. Maintaining pressure until the material sets will help to ensure there are no air pockets and thus voids. When filling a cavity in a closed top base make sure there are sufficient vent holes in the corners of the compartments where the grout is filled. When in doubt add additional vent holes to help ensure trapped air is released to minimize any voids. After the grout has been mixed all cleanup should take place immediately. Tools can be cleaned with water and agitation. A power washer usually does the trick.
Step 9: Stripped Form Work
The grout is now fully cured and you are ready to strip the forms. Generally, this is done 24 hours after the last grout is poured, however API states that the forms should not be removed for at least 48 hours after the last grout pour. Your forms should come off easily, provided they were properly waxed. Now make sure there are no sharp corners on the grout and the chamfered edges came out as expected. They may need a little touch up if so you can take a grinder to smooth out the edges or cut in a chamfer if needed. Once the forms are removed the temporary leveling bolts or jack screws need to be loosened or removed. If they are removed, make sure the hole is filled up as to not allow any liquids to get into the hole. After and only after the jack bolts are removed or loosened should you commence taking the final torque sequence on the anchor bolts.
Step 10: Final Product
Now that your base is properly set the pump and motor can be reinstalled to the base. Now, final piping can be landed to the suction and discharge flange of the pump. Please note that no piping should be attached prior to grouting or setting of the equipment as it can cause a strain on the equipment which it was not designed to withstand.
For additional information on pipe strain please click the learn more button below.