Pictured above: Fabricator inspecting weld on skid
Skid-Mounted Units: ASME-Compliant Modular Engineering Solutions
Skid-mounted units, often referred to simply as “skids,” are self-contained process systems or equipment packages that are fabricated off-site and delivered as turnkey modules. These units are engineered and built to meet industry codes; including ASME Boiler and Pressure Vessel Code (BPVC) and associated piping standards ensuring performance, safety, and compliance across demanding applications.
Skids are a hallmark of modular design in industries such as oil & gas, chemical processing, power generation, water treatment, and food and beverage.
What Is a Skid-Mounted Unit?
A skid is a pre-engineered and pre-assembled system that is mounted on a structural steel base (the “skid”) and designed to be easily transported, installed, and integrated into a larger process system.
Typical skid-mounted systems may include:
- Pressure vessels and heat exchangers
- ASME B31.1 or B31.3-compliant piping networks
- Pumps, valves, filters, and instrumentation
- Control panels and safety systems
- Structural support frames
These are built as a cohesive unit in a controlled fabrication environment, then shipped as one piece or a few modular components ready for connection and commissioning on-site.
ASME Code Compliance in Skid Fabrication
Skid-mounted systems are subject to the same rigorous standards as individually fabricated components. Common ASME standards integrated into skid design include:
ASME Section VIII Division 1 or 2
For any pressure vessels used within the skid, ensuring they meet design pressure, material, and fabrication requirements.
- ASME B31.1 / B31.3 Piping Codes
For all pressure and process piping, depending on whether the system is considered power piping (B31.1) or process piping (B31.3). These codes govern:
- Pipe sizing and thickness
- Support and restraint design
- Thermal expansion and flexibility analysis
- Material and weld specification
- Non-destructive testing (NDE)
- WPS, PQR & Welder Qualification
All welding work on skid systems must comply with ASME Section IX, with validated Welding Procedure Specifications (WPS) and Procedure Qualification Records (PQR).
- Professional Engineer (P.E.) Review & Certification
Most skid systems require engineering validation and certification by a licensed P.E., particularly for pressure-retaining items and regulated installations.
Advantages of Skid-Mounted Systems
Modular Efficiency
Skids can be designed, built, and tested independently from site constraints, dramatically reducing construction time and coordination issues in the field.
Cost and Time Savings
Off-site fabrication reduces on-site labor costs, accelerates commissioning, and minimizes disruptions to ongoing operations.
Quality Control
Manufacturing in a controlled shop environment leads to better QA/QC, improved weld quality, and fewer rework issues.
Ease of Transport and Installation
The entire system is mounted on a base frame designed for forklift or crane handling, simplifying logistics and minimizing installation steps.
Safety and Compliance
ASME-coded skids ensure the entire system—vessels, piping, and supports—is built to meet rigorous safety and performance standards.
Pictured above: Skid-Mounted Units Diagram
Applications for ASME-Certified Skid Packages
Skid-mounted systems are widely used for:
- Fuel gas conditioning systems
- Boiler feedwater skids
- Chemical injection skids
- Water purification and treatment units
- Compressed air and gas systems
- Lube oil or hydraulic skids
Each skid is custom-designed to the project’s needs and built for plug-and-play integration, reducing start-up times and improving reliability.
Why ASME-Compliant Skids Are a Smart Choice
Combining the benefits of modularity with the confidence of ASME compliance, skid-mounted units represent the future of scalable and efficient process system design. Whether you’re upgrading a legacy facility or building new, ASME skid systems offer flexibility, safety, and performance with minimal disruption to your operation.
