Welded or Cast GIS Enclosures: Fabrication and Inspection Choices
Choose enclosure construction from geometry, material and batch needs, then agree weld, dimensional, pressure and leak-test acceptance.
Selection note: use this guide to compare technical requirements. Confirm catalog ranges, typical values and standard clauses against the model, edition and agreed test conditions; project acceptance follows the approved drawings and technical agreement.
On this page
- 01When should GIS OEMs specify Welded Aluminum Enclosures (GWE) vs Cast Enclosures (GCE)?
- 02How should GIS welds be inspected for porosity and leakage?
- 03Why are IT6 flange flatness and Ra 0.8 sealing grooves critical for GIS enclosures?
- 04How are GIS internal high-conductivity conductors (GCA) matched to the enclosure?
- 05Frequently asked questions
- 06Standards & sources
In short
Select cast or welded construction from enclosure geometry, batch size, alloy, gas pressure and the approved inspection plan.
- Aluminum alloy selection affects enclosure electromagnetic heating; review material and temperature-rise evidence at the specified current.
- Choose precision sand/low-pressure aluminum casting (GCE) for compact 3-way/4-way housings; choose CNC plate-rolled and TIG/MIG welded fabrication (GWE) for large 252 kV to 800 kV vessels.
- Specify gas pressure, sealing faces, weld or casting inspection and conductor interfaces on the manufacturing drawing.
- Floor-type 5-axis CNC boring and heavy-duty pipe-end lathes hold flange perpendicularity to IT6 and O-ring sealing grooves to Ra 0.8.
- High-conductivity silver-plated copper/aluminum internal conductors (GCA, 126 kV to 1100 kV) complete the coaxial gas-chamber assembly.
Quote the enclosure against an approved drawing revision, material grade, pressure duty and agreed leak and dimensional checks.
01When should GIS OEMs specify Welded Aluminum Enclosures (GWE) vs Cast Enclosures (GCE)?
Cast aluminum enclosures (GCE) are ideal for standardized 72.5 kV to 252 kV disconnector, earthing switch, CT/VT and compact tee housings where complex curved geometries and integrated mounting bosses are produced in volume. Welded aluminum enclosures (GWE) are preferred for 252 kV to 800 kV circuit breaker tanks, long busbar ducts and custom 4-way to 6-way headers where wrought aluminum plate delivers higher ductility, avoid casting-porosity concerns and rapid geometry customization without pattern tooling.
At higher voltages (363 kV, 550 kV and 800 kV), enclosure diameters and internal volumes grow substantially. Fabricating the shell from wrought marine/pressure-vessel grade aluminum alloy plate on a 3-roller CNC heavy bending roll yields uniform wall thickness and superior burst safety margins, while forged or machined nozzles are welded at the exact branch angles required by the substation layout.
02How should GIS welds be inspected for porosity and leakage?
Inspect the weld procedure and seam geometry, apply the agreed NDT method to the specified joints, then pressure and leak-test the finished enclosure to the project criteria.
Record which seams were examined, the inspection method and acceptance level, and the measured pressure and leakage results.
- Step 1 (CNC Plate Rolling): 3-roller CNC bending controls cylinder roundness and ellipticity.
- Step 2 (Automated Rotary Welding): robotic/automated TIG & MIG welding on multi-axis positioners.
- Step 3 (Acceptance): inspect the specified welds, then perform dimensional, pressure and leak checks on the finished tank.
| Feature / Criterion | GIS Welded Enclosures (GWE) | GIS Cast Enclosures (GCE) | GIS Internal Conductors (GCA) |
|---|---|---|---|
| Voltage Range | 72.5 kV to 800 kV | 72.5 kV to 800 kV (per design) | 126 kV to 1100 kV |
| Primary Process | CNC plate rolling + rotary TIG/MIG welding | Precision aluminum alloy casting + heat treatment | Extruded/forged conductor turning + silver plating |
| Optimal Geometries | Large breaker tanks, bus ducts, 4/6-way headers | Compact tees, crosses, disconnector/CT housings | Coaxial busbars, plug-in contacts, corona shields |
| Machining Precision | 5-axis CNC boring to IT6; grooves Ra 0.8 | CNC milled flanges & O-ring sealing faces | Mirror-polished outer surface; concentricity <= 0.05 mm |
| NDT & Pressure QC | Specified weld NDT plus pressure and leak tests | X-ray casting inspection + pressure/leak test | Conductivity (%IACS), plating thickness & roughness check |
| Tooling Lead Time | No casting pattern for a welded design; confirm tooling and lead time | Casting tooling required; compare cost by batch | Direct CNC production from customer CAD drawings |
03Why are IT6 flange flatness and Ra 0.8 sealing grooves critical for GIS enclosures?
Flange alignment and sealing-groove finish affect gasket compression and gas tightness. Treat IT6 and Ra 0.8 as drawing targets only where specified, and inspect the finished surfaces.
Machining mating flanges in one setup can help maintain alignment; confirm axes, bolt patterns and sealing surfaces with dimensional inspection.
“Buyer check: choose cast or welded construction from geometry and batch needs, then agree pressure and leakage inspection.”
04How are GIS internal high-conductivity conductors (GCA) matched to the enclosure?
Match conductor diameter, supports and contacts to the enclosure clearances and current duty; review both drawings as one assembly.
Request conductor material, plating, dimensional and electrical inspection records for the offered assembly.
Applicable EONOVA Equipment
Conclusion
Send the drawing revision, alloy, cast or welded route, gas pressure, leak and NDT criteria, surface treatment and quantity for a comparable quote.
Talk to an EONOVA engineerFrequently Asked Questions
What documentation and NDT reports accompany the quoted supplier GIS enclosures?
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Request the approved drawing revision, material certificate, weld or casting inspection records, dimensional report, and pressure and leak-test results for the delivered tank.
Can the quoted supplier supply complete pre-machined, pressure-tested and painted GIS tanks ready for clean-room assembly?
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Confirm the delivery scope on the drawing and inspection plan: machining, coating, cleanliness, pressure test and leak test may each need separate acceptance.
How do I request a quotation for custom GIS welded or cast enclosures?
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Send your 2D manufacturing drawings (PDF/DWG) and 3D STEP models along with the aluminum alloy grade, design/test pressure, NDT standard, surface coating specification and annual batch volume to our engineering desk.
Standards & Sources
- [1]IEC 62271-203: Gas-insulated metal-enclosed switchgear for rated voltages above 52 kV
International Electrotechnical Commission (TC 17)
Supports: Design pressure, routine pressure testing (1.3x to 2.0x), burst safety factors and gas tightness limits for GIS enclosures.
- [2]CIGRE TB 163: Guidelines for the Design and Testing of GIS Enclosures
CIGRE Working Group 23.10
Supports: Comparison of wrought welded vs cast aluminum enclosures, weld inspection and pressure vessel codes.
- [3]ISO 17636-2: Non-destructive testing of welds: Radiographic testing using X- and gamma-rays with digital detectors
International Organization for Standardization
Supports: Digital X-Ray Radiography (DR) quality classes for full-penetration aluminum pressure welds.
- [4]GB/T 7674: Gas-insulated metal-enclosed switchgear for rated voltages of 72.5 kV and above
Standardization Administration of China
Supports: Enclosure temperature rise, flange sealing and internal fault containment requirements.
Selection guidance for buyers. Confirm specifications and test evidence for the quoted model and supplying entity.
