WHAT IS AN EQUIPMENT SKID BASE, AND HOW IS IT BUILT?
A skid base is a welded structural steel frame that equipment gets mounted to, piped up on, and then moved as a single unit. Instead of setting a pump, motor, filter, or tank on a concrete pad and connecting everything in the field, the whole package is built on the skid in a shop, then lifted or dragged into place and anchored.
The equipment on top gets most of the attention. The base is what decides whether that equipment stays aligned, survives the trip, and sets down level on site.
Published October 6, 2026 · JMC Fabrication
Shop assembly is faster and more controlled than field assembly. Alignment, piping fit-up, and testing happen on a level shop floor with the right tools and no weather. The finished package ships ready to set, which shortens the time crews spend on site, and that matters a lot on refinery turnarounds, offshore and marine work, and any job where site hours are expensive.
A skid also makes equipment portable. A package built on a proper base can be relocated later without tearing it apart.
- The main frame — Usually wide flange beams or channel around the perimeter with cross members under each piece of equipment. Tube steel shows up on lighter skids. Member size comes from the equipment weight, the span between supports, and the loads from lifting, which is often the worst case the frame ever sees.
- Mounting pads — Equipment doesn't bolt straight to the beams. It sits on raised steel pads welded to the frame, which are leveled or machined flat so the equipment can be aligned with a reasonable amount of shimming.
- Deck plate and drip lip — Many skids are decked with plate, often checker plate for footing, and finished with a raised lip around the edge so leaks and washdown stay on the skid. A drain connection lets that liquid be piped away.
- Lifting and handling points — Lifting lugs sized for the full loaded weight and placed around the center of gravity so the skid hangs level, plus forklift pockets on smaller skids. Some bases get tow or drag points for sliding into place.
- Anchoring and grout — Anchor bolt holes or clips that match the foundation drawing, and on heavier rotating equipment, grout holes and vent holes so the base can be filled solid once it's set.
A base that twists during welding will throw off every piece of equipment mounted to it. Shops control this with weld sequencing, fixturing the frame while it's welded, and checking the mounting pads for flatness and coplanarity before equipment goes on. Pump bases built to API 610, for example, carry specific requirements for mounting pad flatness and base stiffness, and many owners write similar requirements into their own specifications.
This is also why the base gets built and checked before anything else touches it. Fixing a warped frame after piping is attached is a much bigger job.
- Equipment list with weights, footprints, and bolt patterns or vendor drawings
- General arrangement drawing showing where each piece sits
- Foundation or anchor bolt layout, if it's already set
- Any lifting, transport, or size limits for getting the skid to site
- Coating requirements, such as a paint system or hot-dip galvanizing
- Applicable specifications, including any owner or API requirements
A skid base is a simple idea, a steel frame under the equipment, that takes real attention to get right: sized for lifting, flat where it matters, with room for piping, drainage, and anchoring.
JMC Fabrication builds structural subbases, mounting frames, and pump skids in-house out of a 50,000 sq ft shop in Pascagoula, MS, working from customer drawings for oil and gas, marine, and industrial projects across the Gulf Coast. For pump packages specifically, see our guide to pump skid design and fabrication.
This article supports the following JMC capabilities: