Mylar Sleeve for Flange Bolt Insulation
Bolt sleeves that break the galvanic path at flanged joints. Flange bolt sleeves insulate the bolt from the flange to stop galvanic corrosion and stray current. We size the sleeve to the bolt and flange drawing. Material is polyester film with the dielectric and wall set by the service voltage and environment. It insulates the bolt from the flange so the galvanic path is broken. We size it to the
Bolt sleeves that break the galvanic path at flanged joints. Flange bolt sleeves insulate the bolt from the flange to stop galvanic corrosion and stray current. We size the sleeve to the bolt and flange drawing. Material is polyester film with the dielectric and wall set by the service voltage and environment. It insulates the bolt from the flange so the galvanic path is broken. We size it to the
Technical specifications
| Material | Polyester film |
| Use | Flange bolt insulation |
| Purpose | Break galvanic path |
| Standard | ASTM D880 (PET film), IEC 60250 (dielectric). |
| Operating temperature | -55 °C to +105 °C |
| Dielectric strength | ≥ 20 kV/mm (per ASTM test method) |
💾 Datasheets & Test Reports
Download the technical data sheet for this product (PDF).
Information required for quotation
| Base tube | Approved material grade, ID, OD, wall and conditioning as per drawing |
| Datums | Drawing datum scheme and measurement reference |
| Key dimensions | Feature positions, depths, pitch and diameters reviewed before quotation |
| Thread / profile | Standard or custom profile, class, depth, engagement and gage method |
| Other features | Holes, slots, steps, chamfers, cuts and marking |
| Acceptance | Tolerances, sampling, gages, FAI and inspection report |
| Order | Prototype and production quantity, packaging and delivery target |
Applications by industry
- Flange and coupling bolt isolation sleeves
- Threaded stud insulating covers in busbar flanges
- Petrol/electric flange joint insulation sleeves
- Anti-corrosion bolt isolation in pipelines and vessels
- Stainless/CS transition flange bolt protection
- Custom-length tubular isolation for ASME flanges
Why mylar (PET) for this application
A PET sleeve breaks the metal-on-metal path through a flanged joint to stop galvanic corrosion whether the flange is live or earthed, sized to the bolt OD and flange width.
Confirm operating temperature under the flange rating; PET is for mild service, not hot process flanges. Match ID to bolt and length to flange faces accurately.
Standards: ASME B16.5 flange geometry; PET dielectric per IEC 60250.
Feature and remaining-wall review
Heat-formed to ID/OD; laser or die-cut for slots and holes. Review feature depth, edge distance and remaining wall against critical geometries. Capability is confirmed on your drawing, not from a blanket tolerance.
Inspection and traceability
We state the control plan with you. Batch traceability links raw material lot to finished part.
- First-article inspection (FAI) per your plan
- In-process dimensional checks at every station
- Batch certificate of conformance (COA) supplied on request
- Lot traceability to incoming material certificate
- Dielectric strength and insulation resistance testing available on request
Related components
Mylar Shrink Tubing
Related insulation component from the WELLELE catalog.
Silicone-Coated Fiberglass Sleeving
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Acrylic Fiberglass Sleeving
Related insulation component from the WELLELE catalog.
Common questions
Is Mylar suitable for wire harnessing?
Yes — good dielectric strength and tear resistance for low-to-moderate temperature wire bundling.
Can Mylar tubing be heat-shrink?
Mylar can be heat-formed but does not shrink like polyolefin. Use for sleeving where dimensional stability matters.
What tolerances can you hold?
ID/OD ±0.1 mm typical for heat-formed Mylar. Tighter with custom die-forming.
Do you ship RoHS and REACH compliant?
Yes. All standard grades comply with RoHS 2011/65/EU and REACH 1907/2006.
Does the sleeve stop galvanic corrosion?
Yes. All standard grades comply with RoHS 2011/65/EU and REACH 1907/2006.
Engineering Guides & Selection Notes
Related technical articles that help specify this product.
Get pricing for Mylar Sleeve for Flange Bolt Insulation
Attach the drawing with annual volume. We check the material against your duty and tolerance, verify ID / OD / wall / features, and respond with manufacturability notes and pricing.