About Us

Helical insert is a fastener made of helically drawn coiled wire. Helically formed coils of diamond shaped stainless steel or phosphor bronze wire screw into a threaded hole to form a mating internal thread for a screw or stud. These inserts provide a convenient means of repairing stripped-out threads and are also used to provide stronger threads in soft materials such as aluminum, zinc die castings, wood, plastic, magnesium etc. than can be obtained by direct tapping of the base metal involved. Other common generic names are Screw Thread Insert (STI) and Wire Thread Insert. Its applications include engine cylinder head repair after unintentional over-torque or cross-threading of spark plugs strips the thread of the socket. Thread Repairing Kits with matched tap and coil exist for this application and many others, where either a damaged thread is repaired or a new thread is formed.

RAPI-COIL has global presence with sales in over 25 countries including U.S.A., U.K., Germany, France, Holland, Austria, Czech Republic, Australia, New Zealand, Far East, Africa & many Middle East countries. Our mission is to achieve sales all over the world to meet any requirements of thread repairing tools users everywhere. We emphasize on top quality and at the same time strive to give our customers “value for money” by keeping our pricing highly competitive.


RAPI-COIL threading inserts provide means for protecting and strengthening all types of tapped threads.

Our inserts are manufactured from 18-8 stainless steel (AISI 304 / AISI 316 / DTD 734A / AMS 7245) and other materials all conforming to international Screw Thread Specs of DIN-8140-1 and others.

Available types – Free Running & Screw Locking

Inserts with Tang and without Tang (Tangless)

Nominal Length – 1.0D, 1.5D, 2.0D, 2.5D, & 3D sizes available

All sizes and pitches available in MM and IMPERIAL

Metric, Imperial, UNC, UNF, BSW, BSF, BA, BSP and BSCycle threads


I'm a paragraph. Click here to add your own text and edit me. Let your users get to know you.

Just fill out this quick form


Thanks for submitting!

What you get


A phone call from one of our business consultants

A cost estimate of your project based upon your submission

An in-person meeting to discuss the finer details if necessary

100% privacy guaranteed, your details are safe and protected