Send a part number, a photo, or a whole BOM — we supply it and stand behind it. Worldwide shipping to 80+ countries.

3G Electric
RFQ CartGet a QuoteSign inSign up
HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, 5/16"-24 Thread Size - Screw-Locking Tanged Helical Inserts
HELI-COILScrew-Locking Tanged Helical Inserts

HELI-COIL Helical Insert: Tanged Tang Style, Screw-Locking, 5/16"-24 Thread Size

The HELI-COIL Helical Insert is a tanged tang style, screw-locking insert with a 5/16"-24 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-528995

Brand
HELI-COIL
Item
Helical Insert: Tanged Tang Style, Screw-Locking, 5/16"-24 Thread Size
Category
Screw-Locking Tanged Helical Inserts
Available to Order
Trade pricing by quote — replies within 24h
Qty
WhatsApp an engineer
No account needed — your quote request goes straight to our engineers. A free account lets you track quotes and re-order faster.
Worldwide Shipping
Air & sea freight
Datasheet on Request
Technical specs
1-Day Quote
Replies within 24h

Technical Specifications

HELI-COIL
Manufacturer Part Number
A3591-5CN781
Type
Screw-Locking, Plain, 100 PK
Tensile Strength
200,000 to 250,000 psi
Finish Type
Plain
Thread Size
5/16"-24
Thread Type
Fine
STI Tap Size
5/16"-24
Thread Direction
Right Hand
Compatible Material
Metal
Material Grade/Class
18-8
System of Measurement
Inch
View Full Spec Sheet

Technical Documents

No technical documents available for this product.
Request documentation →
Not sure this is the right part? Get a recommendation.

Need installation or engineering help?

Installation, commissioning, maintenance plans, system design, and bundled product + service quotes — one team handles the full scope.
Talk to an engineer

Ask a question

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 5/16"-24 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 100-piece pack (MPN A3591-5CN781).

Frequently Asked Questions

What is a HELI-COIL helical insert used for?

A HELI-COIL helical insert repairs or reinforces threads in metal. This screw-locking tanged tang style, 5/16"-24 fine thread, 18-8 stainless steel insert provides strong, wear-resistant threads in aluminum, cast iron, or steel components, preventing thread stripping under high loads.

What are the specifications of the HELI-COIL A3591-5CN781 insert?

This HELI-COIL insert has a 5/16"-24 fine thread, 18-8 material grade, plain finish, and tensile strength of 200,000 to 250,000 psi. It is a screw-locking tanged tang style, right-hand thread, compatible with metal, and comes in a 100-piece pack (MPN A3591-5CN781).

Where to buy HELI-COIL helical inserts worldwide?

3G Electric supplies HELI-COIL helical inserts worldwide. As a global industrial solutions provider, we handle full logistics and customs clearance to deliver this 5/16"-24 screw-locking insert (A3591-5CN781) to your facility. Contact us for availability and lead time.

How to install a HELI-COIL tanged tang insert?

To install a HELI-COIL tanged tang insert, drill the hole to the specified STI tap size (5/16"-24), tap threads with the correct STI tap, then use a tang installation tool to wind the insert into place. After installation, break off the tang with a punch. Always follow the manufacturer's instructions.

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.

You might also need

Burners & Combustion →Pumps & Compressors →Spare Parts →All Products →

More from HELI-COIL

View all HELI-COIL parts →
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
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.
HELI-COIL
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.
HELI-COIL
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.
HELI-COIL
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.
HELI-COIL
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.
HELI-COIL
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.
HELI-COIL
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.