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HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, 1/4"-28 Thread Size, Plain - Screw-Locking Tanged Helical Inserts
HELI-COILScrew-Locking Tanged Helical Inserts

HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, 1/4"-28 Thread Size, Plain

The HELI-COIL Helical Insert is a tanged tang style, screw-locking insert with a 1/4"-28 fine thread, plain finish, and 18-8 material grade. It offers a tensile strength of 200,000 to 250,000 psi, is compatible with…

SKU 3G-OTH-528973

Brand
HELI-COIL
Item
Helical Insert: Tanged Tang Style, Screw-Locking, 1/4"-28 Thread Size, Plain
Category
Screw-Locking Tanged Helical Inserts
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Technical Specifications

HELI-COIL
Manufacturer Part Number
3591-4CN250S
Type
Screw-Locking, Plain, 1,000 PK
Tensile Strength
200,000 to 250,000 psi
Finish Type
Plain
Thread Size
1/4"-28
Thread Type
Fine
STI Tap Size
1/4"-28
Thread Direction
Right Hand
Compatible Material
Metal
Material Grade/Class
18-8
System of Measurement
Inch
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HELI-COIL Products
3G Electric (S) Pte. Ltd. — Singapore

Product Description

The HELI-COIL Helical Insert is a tanged tang style, screw-locking insert with a 1/4"-28 fine thread, plain finish, and 18-8 material grade. It offers a tensile strength of 200,000 to 250,000 psi, is compatible with metal, and comes in a 1,000 PK. This inch-system insert requires an STI tap size of 1/4"-28 and has a right-hand thread direction.

Frequently Asked Questions

What is a HELI-COIL helical insert used for?

A HELI-COIL helical insert repairs or reinforces threaded holes in metal. The screw-locking design resists vibration loosening. It is commonly used in automotive, aerospace, and industrial maintenance to restore stripped threads or strengthen connections in softer materials.

What are the specifications of the HELI-COIL 3591-4CN250S insert?

This HELI-COIL insert has a 1/4"-28 fine thread, 18-8 material grade, and tensile strength of 200,000 to 250,000 psi. It is a tanged tang style, screw-locking, plain finish, right-hand thread, and comes in a 1,000 PK. Requires an STI tap size of 1/4"-28.

Where to buy HELI-COIL helical inserts worldwide?

3G Electric supplies HELI-COIL helical inserts worldwide. As a global industrial sourcing partner, we handle logistics, customs clearance, and delivery to your location. Contact us for pricing and lead time on the 3591-4CN250S or other thread sizes.

How to install a HELI-COIL screw-locking insert?

Drill out the damaged thread to the specified STI tap size (1/4"-28 for this insert), tap the hole with the corresponding STI tap, then use a tang installation tool to wind the insert into the hole. Break off the tang after installation. Ensure the hole is clean and lubricated.

Used in

Common applications for HELI-COIL
Aerospace engine repair — HELI-COIL STI taps for M12x1.75 metric threads in aluminum alloy components
Automotive transmission rebuild — HELI-COIL STI taps for 7/16-14 UNC threads in cast iron housings
Industrial pump maintenance — HELI-COIL STI taps for #10-32 UNF threads in stainless steel pump bodies
Hydraulic cylinder repair — HELI-COIL STI taps for M6x1 metric threads in steel cylinder heads
General manufacturing — HELI-COIL STI taps for 9/16-18 UNF threads in machinery base plates

HELI-COIL Products

3G Electric supplies HELI-COIL screw-locking tanged helical inserts. We supply genuine products with in-stock availability on common SKUs, technical documentation, commissioning support, and warranty service — worldwide.

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HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, #10-32 Thread Size, Plain, Plain, 100 PK (MPN A3591-3EN285). Key specifications — Material Grade/Class: Nitronic 60; Thread Direction: Right Hand; STI Tap Size: #10-32; Compatible Material: Metal; System of Measurement: Inch; Brand: HELI-COIL; Tensile Strength: 200,000 psi; Thread Type: Fine.
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HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, #10-32 Thread Size, Plain, Plain, 100 PK (MPN A3591-3EN285). Key specifications — Material Grade/Class: Nitronic 60; Thread Direction: Right Hand; STI Tap Size: #10-32; Compatible Material: Metal; System of Measurement: Inch; Brand: HELI-COIL; Tensile Strength: 200,000 psi; Thread Type: Fine.
HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, M6-1.00 Thread Size, Plain, 100 PK (MPN A4184-6EN120). Key specifications — Material Grade/Class: Nitronic 60; Thread Direction: Right Hand; STI Tap Size: M6-1.00; Compatible Material: Metal; System of Measurement: Metric; Brand: HELI-COIL; Drill Bit Size: 6.25mm; Tensile Strength: 200,000 psi.
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HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, M6-1.00 Thread Size, Plain, 100 PK (MPN A4184-6EN120). Key specifications — Material Grade/Class: Nitronic 60; Thread Direction: Right Hand; STI Tap Size: M6-1.00; Compatible Material: Metal; System of Measurement: Metric; Brand: HELI-COIL; Drill Bit Size: 6.25mm; Tensile Strength: 200,000 psi.
HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, 1 1/4"-12 Thread Size, Plain, 100 PK (MPN A3591-20CN1250). Key specifications — Material Grade/Class: 18-8; Thread Direction: Right Hand; STI Tap Size: 1-1/4"-12; Compatible Material: Metal; System of Measurement: Inch; Brand: HELI-COIL; Tensile Strength: 200,000 to 250,000 psi; Thread Type: Fine.
HELI-COIL
HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, 1 1/4"-12 Thread Size, Plain, 100 PK (MPN A3591-20CN1250). Key specifications — Material Grade/Class: 18-8; Thread Direction: Right Hand; STI Tap Size: 1-1/4"-12; Compatible Material: Metal; System of Measurement: Inch; Brand: HELI-COIL; Tensile Strength: 200,000 to 250,000 psi; Thread Type: Fine.
HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, M4-0.70 Thread Size, 100 PK (MPN A4184-4CNW060). Key specifications — Material Grade/Class: 18-8; Thread Direction: Right Hand; STI Tap Size: M4-0.70; Compatible Material: Metal; System of Measurement: Metric; Brand: HELI-COIL; Drill Bit Size: 4.2mm; Tensile Strength: 200,000 to 250,000 psi.
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HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, M4-0.70 Thread Size, 100 PK (MPN A4184-4CNW060). Key specifications — Material Grade/Class: 18-8; Thread Direction: Right Hand; STI Tap Size: M4-0.70; Compatible Material: Metal; System of Measurement: Metric; Brand: HELI-COIL; Drill Bit Size: 4.2mm; Tensile Strength: 200,000 to 250,000 psi.
HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, 5/16"-18 Thread Size, Plain, 100 PK (MPN A3585-5CN469). Key specifications — Material Grade/Class: 18-8; Thread Direction: Right Hand; STI Tap Size: 5/16"-18; Compatible Material: Metal; System of Measurement: Inch; Brand: HELI-COIL; Tensile Strength: 200,000 to 250,000 psi; Thread Type: Coarse.
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HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, 5/16"-18 Thread Size, Plain, 100 PK (MPN A3585-5CN469). Key specifications — Material Grade/Class: 18-8; Thread Direction: Right Hand; STI Tap Size: 5/16"-18; Compatible Material: Metal; System of Measurement: Inch; Brand: HELI-COIL; Tensile Strength: 200,000 to 250,000 psi; Thread Type: Coarse.
HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, 1/4"-28 Thread Size, 100 PK (MPN A3591-4CNW500). Key specifications — Material Grade/Class: 18-8; Thread Direction: Right Hand; STI Tap Size: 1/4"-28; Compatible Material: Metal; System of Measurement: Inch; Brand: HELI-COIL; Tensile Strength: 200,000 to 250,000 psi; Thread Type: Fine.
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HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, 1/4"-28 Thread Size, 100 PK (MPN A3591-4CNW500). Key specifications — Material Grade/Class: 18-8; Thread Direction: Right Hand; STI Tap Size: 1/4"-28; Compatible Material: Metal; System of Measurement: Inch; Brand: HELI-COIL; Tensile Strength: 200,000 to 250,000 psi; Thread Type: Fine.
HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, M4-0.70 Thread Size, Plain, 1,000 PK (MPN 4184-4CN040S). Key specifications — Material Grade/Class: 18-8; Thread Direction: Right Hand; STI Tap Size: M4-0.70; Compatible Material: Metal; System of Measurement: Metric; Brand: HELI-COIL; Drill Bit Size: 4.2mm; Tensile Strength: 200,000 to 250,000 psi.
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HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, M4-0.70 Thread Size, Plain, 1,000 PK (MPN 4184-4CN040S). Key specifications — Material Grade/Class: 18-8; Thread Direction: Right Hand; STI Tap Size: M4-0.70; Compatible Material: Metal; System of Measurement: Metric; Brand: HELI-COIL; Drill Bit Size: 4.2mm; Tensile Strength: 200,000 to 250,000 psi.
HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, #10-32 Thread Size, Plain, Plain, 100 PK (MPN A3591-3CN190). Key specifications — Material Grade/Class: 18-8; Thread Direction: Right Hand; STI Tap Size: #10-32; Compatible Material: Metal; System of Measurement: Inch; Brand: HELI-COIL; Tensile Strength: 200,000 to 250,000 psi; Thread Type: Fine.
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HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, #10-32 Thread Size, Plain, Plain, 100 PK (MPN A3591-3CN190). Key specifications — Material Grade/Class: 18-8; Thread Direction: Right Hand; STI Tap Size: #10-32; Compatible Material: Metal; System of Measurement: Inch; Brand: HELI-COIL; Tensile Strength: 200,000 to 250,000 psi; Thread Type: Fine.