Insulating Shoulder Washers
| Standard | ASTM D4066 ref · OEM |
|---|---|
| Material | PEEK / PPS / PA66 |
| Strength Grade | — |
| Size Range | Project range |
| Surface Treatment | Natural / Black |
01
Product Description
Product Description & Key Specifications
Insulating shoulder washers are non-conductive polymer washers with an integrated sleeve or shoulder that helps isolate the bolt or stud shank from the surrounding hole. They are used where both the bearing face and the fastener body need electrical separation from metallic equipment, flange hardware or structural plates.
Material selection depends on temperature, chemical exposure, compression load, dielectric requirement and installation geometry. PA66 is a practical option for light-duty electrical isolation and panel assemblies, PPS provides improved thermal and chemical resistance compared with general nylon, and PEEK is selected for higher-performance insulating joints, chemical exposure and tighter dimensional stability requirements.
These washers are commonly produced to OEM drawings because shoulder outside diameter, shoulder height, washer thickness, hole clearance and bearing diameter must match the joint design. Natural and black material colors are available; UV, temperature and certificate requirements should be confirmed before production.
| Product type | Insulating shoulder washers / bolt isolation bush washers |
|---|---|
| Standards | OEM drawing / ASTM D4066 material reference |
| Material | PEEK / PPS / PA66 |
| Strength grade | Project-specific polymer grade, not a steel strength class |
| Size range | Project range by drawing |
| Common models | M6, M8, M10, M12, M16 and drawing-based shoulder dimensions |
| Washer form | Flat bearing washer with molded or machined insulating shoulder |
| Surface finish | Natural / Black polymer surface |
| Matched hardware | Stud bolts, heavy hex nuts, insulating sleeves and flange isolation kit components |
| Documentation | CoC, material data sheet, dimensional report and polymer certificate on request |
02
Selection
Selection Advantages by Application
Flange Isolation and Cathodic Protection
PEEK, PPS or PA66 shoulder washers are used in flange isolation kits to help electrically separate studs from flanges. Confirm dielectric requirement, flange class, washer stack and operating temperature before ordering.
Oil and gas fastenersPower Equipment and Electrical Panels
Non-conductive shoulder washers support transformer, switchgear, busbar support and equipment panel assemblies where bolt isolation and controlled clearance around holes are required.
Power generation fastenersCustom Insulating Hardware
Drawing-based shoulder washers are suitable for OEM assemblies where a standard flat washer cannot control both bearing insulation and shank isolation in one component.
Industrial equipment fasteners03
Assembly
Recommended Matching Products
04
Manufacturing
Manufacturing & Quality Control
Manufacturing CapabilityQuality Control
CNC machining or molding according to shoulder geometry and quantityIncoming PEEK / PPS / PA66 material verification and batch traceability
Custom shoulder height, outside diameter and bore clearance by drawingDimensional inspection for ID, OD, thickness, shoulder OD and shoulder height
Natural or black polymer supply with optional UV-stabilized material reviewVisual inspection for burrs, chips, sink marks and surface defects
Prototype and production batches for flange isolation or electrical assembliesDielectric, compression or material tests arranged when specified
Bagged, kitted or flange-set packagingCoC, material data sheet and inspection report prepared on request
05
FAQ
Common Questions Before RFQ
What is an insulating shoulder washer used for?
It isolates both the bearing surface and the bolt or stud shank from a surrounding hole, helping prevent electrical contact between the fastener and the mating metal part.
Should I choose PEEK, PPS or PA66?
PA66 is suitable for many light-duty insulating joints, PPS is used for higher temperature or chemical resistance, and PEEK is selected for more demanding temperature, chemical and dimensional stability requirements.
Are shoulder washers standard sizes?
Some common sizes can be supplied, but most insulating shoulder washers are made to drawings because shoulder height and shoulder diameter must match the hole and washer stack.
Can they be used in flange isolation kits?
Yes. They can be used in flange isolation kits when the polymer material, thickness, dielectric performance and service conditions are approved by the project specification.
What RFQ details are needed?
Send material, color, bolt size, hole diameter, shoulder height, washer OD, washer thickness, quantity and any dielectric, temperature or certificate requirements.
Need custom insulating shoulder washers?
Send your washer drawing, polymer material, bolt size, shoulder dimensions, color, operating temperature and certificate requirements. We can quote PEEK, PPS or PA66 shoulder washers for electrical isolation and flange kits.
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