Snap-On Caps Information

SAP-SEAL® PRODUCTS, INC. markets three styles of caps that permanently prevent corrosion by covering and sealing industrial nuts and bolts. These caps are commonly referred to as bolt caps, nut caps, bolt cover caps, flange bolt protection caps, screw-on caps, bolt thread protectors, structural bolt caps, and anchor bolt caps.

Snap On

Screw On


Series 10

Without Washer
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Series 20

With Washer
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Series 30

With non-standard washer and other specials
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Series 10T

Without Washer

Series 30B

No Washer
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Series 20T

With Washer

Series 30BM

No Washer

SAP-SEAL® Specialty Products

SAP-SEAL® PRODUCTS, INC. also markets specialty products that permanently prevent corrosion on industrial nuts, bolts, and valves. These caps are customized—including color—for special applications and situations.

The standard version of our screw and bolt protection caps is black, RAL 9005. This hue is particularly UV-resistant.

We are also able to manufacture very appealing colored protection caps for your individual application, on the basis of the RAL Classic color range. UV resistance is ensured in this case by addition of a special-purpose UV stabilizer.


SAP-SEAL® Screw On Caps are applied utilizing the exposed bolt threads. A minimum of 4 exposed bolt threads is required for standard nuts and a minimum of 6 exposed threads for Heavy Hex nuts. These caps are available with a rust inhibitor installed in the tower portion of the cap. They are easily removed and replaced. Regular as well as heavy hex nuts can be covered. A stud bolt (threads on each end) must be used if both ends of the bolt are to be capped.


SAP-SEAL® Snap On Caps are applied by utilizing a soft hammer or by hand pressure allowing the bottom edge of the cap to slide under the beveled bottom of the nut. If a rust inhibitor is to be used it must be applied as a separate operation by the end user. This style cap is also reusable. Heavy hex nuts must be used for all sizes. Bolt head covers are available for structural bolts only.


SAP-SEAL® Combination Caps were recently developed to protect oversized washers and anchor bolts located at the bases of wind towers. These modular caps allow you to build custom products without incurring the cost of new moulds.

See how they’re installed >