Mylar sleeve for flange bolt insulation
WELLELE supplies Mylar sleeves for flange bolt insulation, bolt isolation, and galvanic corrosion protection. Custom sizes, cut-to-length supply, and kit options are available
- AIt is suitable for flange assemblies that require a thin-wall insulation sleeve with good dielectric performance, low water absorption, and better installation toughness than brittle phenolic sleeves.
Mylar sleeve for flange bolts is a polyester film insulating tube fitted over a flange bolt. It helps isolate the bolt from the flange hole and is commonly used in flange insulation kits to reduce electrical contact between dissimilar metals.
Mylar sleeves for flange bolts
WELLELE supplies Mylar sleeves for flange bolts used in pipe flanges, gasket sets, and industrial flange insulation kits. The sleeve sits over the bolt shank and helps keep the bolt electrically separated from the flange hole.
That detail matters when two different metals are bolted together. Without proper isolation, the bolt path can become part of the corrosion problem. A correctly sized Mylar sleeve helps reduce direct metal-to-metal contact and supports galvanic corrosion control in the flange connection.
Most projects use the sleeve together with insulating washers, steel washers, and an isolating gasket. We can supply sleeve material in standard lengths or cut it to match the bolt length required for your flange assembly
When to specify Mylar sleeves in flange assemblies
- To isolate bolts from dissimilar metal flanges.
- To reduce direct electrical contact inside the bolt hole.
- To support galvanic corrosion control in flange connections.
- To add a thin but tough insulation barrier around the bolt.
- To reduce cracking problems sometimes seen with phenolic sleeves during installation.
- To match standard flange bolts, with cut-to-length options when needed.
- To build a complete insulation kit with washers and an isolating gasket.
Where the sleeves are used
Mylar isolating sleeves are used wherever the bolt needs to be separated from the flange body. Typical applications include:
• Pipe flange insulation kits
• Industrial gasket assemblies
• Oil, gas, water, and chemical pipeline flanges
• Maintenance replacement for damaged bolt insulation sleeves
• Flange connections using dissimilar metals
• Custom polyester film tube applications where a thin insulating sleeve is suitable
Product specifications
| Item | Available option |
|---|---|
| Product name | Mylar sleeve, Mylar isolating sleeve, Mylar tube for flange bolts |
| Material | Spiral-wound polyester film, commonly called Mylar |
| Main use | Bolt insulation and electrical isolation in flange assemblies |
| Inside diameter | Custom range available; source brief lists 0.66 mm to 70 mm and 5 mm to 80 mm ranges |
| Wall thickness | 0.03 mm to 1 mm; flange sleeve wall thickness depends on size and design |
| Length | 2 m per piece available; source brief also mentions 900 mm and 1000 mm standard lengths |
| Color | Transparent or striped Mylar tubing options |
| Temperature reference | Source brief gives both up to 149 C and -60 C to +130 C references |
| Related parts | Insulating washers, steel washers, isolating gasket, G10/G11 or phenolic washer options |
The source file includes more than one size and temperature range. Keep this cautious wording until WELLELE confirms the exact range for this page.
Test data from the source brief
Mylar sleeve or phenolic sleeve?
Custom supply options
What is a Mylar isolating sleeve used for?
It covers the flange bolt and helps keep the bolt electrically separated from the flange hole. This helps reduce direct contact between dissimilar metals in the flange connection.
Is a Mylar sleeve the same as a flange insulation sleeve?
It is one type of flange insulation sleeve. In flange insulation kits, the Mylar sleeve is usually used with insulating washers, steel washers, and an isolating gasket.
Why use Mylar instead of phenolic sleeves?
The supplied product brief recommends Mylar because it is tougher during installation. Phenolic sleeves can crack more easily when bolts are tightened or when the sleeve is handled roughly on site
Can WELLELE cut Mylar sleeves to bolt length?
Yes. Mylar sleeves can be supplied in standard lengths or cut to suit the bolt length. Please confirm bolt size, flange thickness, washer stack, and required sleeve length before ordering.
Can the sleeve be supplied as part of a flange insulation kit?
Yes. Depending on the project, WELLELE can supply the sleeve alone or with steel washers, insulating washers, and an isolating gasket.