HELI-COIL Thread Repair Kit: Tanged Tang Style, Free-Running, 1"-8 Thread Size
The HELI-COIL Thread Repair Kit (MPN 5521-16) is a tanged tang style, free-running insert and tool kit for repairing 1"-8 coarse, right-hand threads in metal. It includes helical inserts made from 18-8 material, with…
SKU 3G-OTH-527878
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Product Description
The HELI-COIL Thread Repair Kit (MPN 5521-16) is a tanged tang style, free-running insert and tool kit for repairing 1"-8 coarse, right-hand threads in metal. It includes helical inserts made from 18-8 material, with an overall length of 1 1/2 in, a plain finish, and an STI tap size of 1"-8. This inch-system kit is designed for metal-compatible applications, sourced and supported by 3G Electric across 14 industrial departments, with specialist depth in combustion, pumps, and controls.
Frequently Asked Questions
What is the HELI-COIL Thread Repair Kit 5521-16 used for?
The HELI-COIL Thread Repair Kit 5521-16 is used to restore damaged 1"-8 coarse, right-hand threads in metal components. It includes helical inserts made from 18-8 material and an STI tap, making it ideal for industrial maintenance across machining, power transmission, and other departments. 3G Electric supplies this kit worldwide.
What are the specifications of the HELI-COIL 5521-16 thread repair kit?
The HELI-COIL 5521-16 kit has a thread size of 1"-8, thread type coarse, and thread direction right hand. It includes free-running helical inserts made from 18-8 material, with an overall length of 1 1/2 in and a plain finish. The STI tap size is 1"-8, and it is compatible with metal substrates.
Where to buy HELI-COIL thread repair kits worldwide?
You can buy HELI-COIL thread repair kits worldwide from 3G Electric, a global industrial solutions provider. We source, supply, and deliver genuine HELI-COIL products like the 5521-16 kit, handling full logistics and customs clearance for international orders. Contact us for availability and lead time.
How to install a HELI-COIL free-running insert?
To install a HELI-COIL free-running insert, drill out the damaged thread to the specified size, tap the hole using the included STI tap (1"-8 for this kit), then wind the insert onto the installation tool and thread it into the tapped hole. Break off the tang after installation. Always follow the manufacturer's instructions for best results.
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3G Electric supplies HELI-COIL insert & tool kits. We supply genuine products with in-stock availability on common SKUs, technical documentation, commissioning support, and warranty service — worldwide.









