INTRODUCTION
A skid-mounted electric heating system combines the heater with selected pumps, valves, piping, instruments, controls, insulation and structural support as one coordinated package.
The key engineering task is not simply mounting components on a frame. The thermal design, hydraulic design, mechanical layout, electrical system, control logic, maintainability, transport limits and site interfaces must work together.
1. Define the Process Duty
Confirm:
- heating medium and composition
- normal / maximum flow
- inlet temperature
- required outlet temperature
- working pressure
- design pressure
- allowable pressure drop
- viscosity versus temperature where relevant
- fouling / solids / water content where relevant
- continuous or intermittent operation
- startup and shutdown requirements
The heater duty should be calculated before the skid layout is finalized.
2. Define the Supply Boundary
Clarify whether the skid includes:
- electric heater
- circulation or transfer pump
- standby pump
- strainer / filter
- valves
- flow instrument
- pressure instruments
- temperature sensors
- expansion vessel where relevant
- piping
- drain / vent
- insulation
- skid frame
- control cabinet
- PLC / HMI
- junction boxes
- field cable inside skid
- local lighting or tracing where required
The scope boundary should identify customer tie-in points for process, power, control and utilities.
3. Heater Selection
The heater type may be:
- inline gas heater
- inline liquid heater
- circulation heater
- thermal-oil heater
- crude-oil / heavy-oil heater
- explosion-proof heater
- multiple heater banks
Review total duty, surface watt density, material, pressure drop, maintenance and hazardous-area requirements.
4. Pump Selection
Where a pump is included, review:
- required process flow
- total differential head
- fluid viscosity
- minimum startup temperature
- NPSH conditions
- motor power
- seal arrangement
- materials
- standby philosophy
- VFD requirement
The pump should be selected from the complete system hydraulic resistance, not only the heater pressure drop.
5. Piping Layout
Review:
- suction and discharge routing
- line size
- heater inlet / outlet orientation
- bypass
- drain and vent
- isolation valves
- check valves
- thermal expansion
- support spacing
- low-point drainage
- high-point venting
- maintenance removal space
Avoid layouts that make heater-bundle removal, pump maintenance or instrument access difficult.
6. Instrumentation
Typical instruments may include:
- inlet temperature
- outlet temperature
- independent high-limit temperature
- inlet pressure
- outlet pressure
- differential pressure
- flow transmitter or switch
- liquid level where relevant
- pump status
- local gauges
Instrument selection should match the process medium, pressure, temperature and hazardous-area classification.
7. Control Philosophy
Possible functions include:
- PID outlet-temperature control
- SCR / thyristor modulation
- staged contactor control
- pump start / stop sequence
- pump / heater interlock
- low-flow trip
- over-temperature trip
- pressure alarm
- valve permissive
- local / remote operation
- PLC / HMI
- DCS communication
8. Hazardous-Area Design
For hazardous installations, confirm:
- area classification
- gas group
- temperature class
- ambient range
- certification route
- terminal-box protection
- field-instrument certification
- control-cabinet location
Do not assume the entire skid must use the same Ex protection technique. Each electrical component should be reviewed according to its location and function.
9. Skid Structure and Transport
Review:
- overall dimensions
- transport width / height
- lifting points
- center of gravity
- forklift pockets where required
- frame stiffness
- equipment loads
- shipping supports
- removable items
- site access
- container or truck limits where applicable
Structural design should account for the actual shipping and installation method.
10. Outdoor and Environmental Design
Possible requirements include:
- rain protection
- dust protection
- anti-corrosion coating
- thermal insulation
- UV exposure
- low-temperature tracing
- high ambient temperature
- wind / sand
- marine atmosphere
11. Maintenance Access
Provide adequate access for:
- heater-element bundle removal
- pump maintenance
- valve operation
- instrument calibration
- terminal-box access
- control-panel service
- insulation removal
- filter cleaning
12. Minimum RFQ Data
For preliminary system selection, provide at least:
- process datasheet and medium composition
- flow, temperature, pressure and allowable pressure drop
- viscosity or other key fluid properties where relevant
- heater duty and electrical supply
- pump / circulation requirement
- hazardous-area and ambient conditions
- control / DCS interface and major instrumentation scope
- supply boundary, site layout and transport restrictions
For a detailed project RFQ, I/O, FAT and documentation checklist, refer to the separate guide:
Industrial Electric Heating System RFQ, I/O, FAT and Documentation Checklist.
Related Xiangyuan Products
Industrial Electric Heating Systems
Skid-Mounted Electric Heating System
Oilfield Skid-Mounted Crude Oil Heating System
Oilfield Electric Heating System
Explosion-Proof Electric Heaters
FAQ
Is a skid-mounted system just a heater mounted on a frame?
Can the customer supply the pump or control cabinet?
Can a skid be supplied pre-assembled?
Can the skid be designed for hazardous areas?
Engineering Note
This series is for technical explanation and preliminary engineering reference. Final skid or system design must be confirmed from the actual medium, process duty, pressure, temperature, hydraulic conditions, hazardous-area requirements, electrical supply, control philosophy, site layout, applicable standards, transport limits and agreed supply scope.
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