Skid-mounted pumps are subjected to mechanical stress induced by vibration. If the vibration isn't kept contained, then these forces can cause damage to the pump, its powerplant and power transmission equipment. On a properly-secured skid, vibration is transferred through the skid and into the ground, thus dampening its effects. That is why more powerful pump skids should be installed on a more permanent foundation; otherwise, any cost savings hoped to be gained by avoiding a grounded installation will be offset by increased pump maintenance and repair expenses. Below are three important considerations to keep in mind when installing skids to solid foundations:
Choose the type of grouting that matches your needs and cost structure
Grouting refers to the use of compounds such as Portland cement or epoxies for the purpose of constructing a solid base of support. Both Portland cement and epoxies have advantages and disadvantages, so be sure you compare needs with costs to determine which is best for your situation. Portland cement is less expensive, but it is also less durable and can be more difficult to use during the pouring process. For example, Portland cement tends to lose its structural integrity in the presence of petroleum products, which is of great significance when used in oilfield operations. Epoxies are higher-priced, but they offer increased durability and their fluid characteristics enable easier pouring into forms. There is no right or wrong choice, but take into consideration the duration of your equipment needs at a given site and base your decision accordingly.
Ensure the skid baseplate is prepared for installation
Another important consideration when installing skids is baseplate preparation. The baseplate, which is the underside of the skid, must be both level and clean to create a strong bond between the skid and foundation. Warped baseplates will not properly adhere due to curvatures across the components, and that requires them to be machined prior to installation. On-site machining costs money and will decrease the bottom line, so be sure to inspect arriving skids to discover flaws that will inhibit grout bonding. In addition, before installing skids, use power washers to strip away soil and other debris that might lessen the adhesion between grout and metal surfaces. If skid surfaces are contaminated with petroleum products, use a degreasing agent along with power washing to remove these compounds.
Prevent voids from forming in the foundation
The most effective of vibrations from the pump machinery to the underlying ground only occurs if the path of transmission is solid. Air pockets in the grouting material will disrupt this process and ultimately lessen the effectiveness of the foundation. That's why it's important to use proper pouring techniques when "grouting" a skid. A couple of things you can do to keep voids from becoming a problem include:
Use multi-level pouring - A single pour of cement or epoxy is often the lowest cost and simplest option, but it also introduces an increased likelihood of void formation in the foundation. The shouldered areas beneath forms can prevent grout materials from flowing into these spaces, though the problem is less acute with epoxies. A double pour of cement or epoxy involves the construction of a single-level form followed by pouring, then repeating the process by constructing a second, top-level form and pouring the second layer. This is more labor-intensive and elevates the cost of pouring, but it does lessen the possibility that voids will be formed.
Use good pouring practices - In all circumstances, you should utilize sound pouring practices to reduce air pocket formation. Create vent holes in the forms so that gases can exit the forms, and be sure that materials are properly mixed before pouring. In addition, closely monitor the curing of the materials so that it doesn't occur too quickly and trap bubbles before gases have an opportunity to escape.