Stainless Steel Three Piece Coupling | UL 514B

Premium SS316 Three-Piece Conduit Couplings for Rigid and IMC Connections

TSI INOX Conduits presents our premium Stainless Steel Three Piece Coupling, a specialized fitting engineered to join threaded ends of rigid stainless steel conduit and IMC where neither length of conduit can be rotated. Manufactured from premium SS316 stainless steel with a vibration polished finish, our three-piece couplings provide rigid, in-line connections with high-quality grounding that will not loosen under vibration.

The Three Piece Coupling is specifically designed for applications where the conduit cannot be turned—a common scenario when connecting pre-installed conduit runs or working with large diameter conduit. This innovative fitting consists of three separate components: a threaded bushing, a sleeve, and a collar, which together allow for secure coupling without rotating either conduit section. Whether you are making repairs, modifications, or completing installations in confined spaces, TSI's stainless steel three-piece couplings deliver the quality, durability, and code compliance your project demands.

View Specifications

Stainless Steel Three Piece Coupling - UL 514B

How Three Piece Couplings Work

Three-piece couplings consist of three principal components that work together to create a rigid, in-line connection without rotating the conduit:

1. Threaded Bushing: The bushing features internal threads for assembly on the threaded end of one conduit and external threads for joining the coupling.
2. Sleeve: The sleeve slips over the second conduit and includes internal threads that engage the external threads of the bushing. When rotated, the sleeve advances on the bushing without rotating either conduit.
3. Collar: The collar has internal threads for assembly on the threaded end of the second conduit. It is retained within the sleeve, allowing the sleeve to rotate freely around it while advancing the collar with the sleeve.

As the sleeve advances on the threaded bushing, its rim engages the collar and pulls the ends of the conduit sections together, creating a rigid, in-line joint.

Key Features

No Conduit Rotation Required

The three-piece design enables coupling without rotating either conduit section, providing critical installation advantages:

Ideal for pre-installed conduit – Connect conduits that cannot be turned
Space-constrained installations – Perfect for confined areas where rotation is impossible
System modifications – Allows for future changes without full disassembly

Rigid In-Line Coupling

The three-piece design provides:

Rigid, in-line connections – Maintains straight conduit runs
Vibration resistance – Will not loosen under vibration
High-quality grounding – Excellent ground continuity

Superior Corrosion Resistance

Manufactured from Type 316 stainless steel to meet stringent sanitary conditions, our three-piece couplings provide:

Superior corrosion resistance – Exceptional protection against chlorides, acids, and saline atmospheres
Molybdenum-enhanced durability – Resists pitting and crevice corrosion in aggressive environments
Sanitary properties – Suitable for food processing, pharmaceutical, and hygienic applications
Long service life – Eliminates lifecycle costs associated with corrosion-related failures

Vibration Polished Finish

The vibration polished finish provides:

Enhanced corrosion resistance – Smooth surface minimizes crevice corrosion
Easy cleaning – Sanitary design suitable for CIP (clean-in-place) systems
Professional aesthetic – Bright, uniform finish that does not require touch-up or painting

Raintight & Concrete-Tight

TSI three-piece couplings are suitable for:

Wet locations – Raintight sealing prevents moisture ingress
Concrete encasement – Concrete-tight for buried applications
Outdoor installations – Withstands weather exposure

Grounding Certification

UL listed for grounding – Meets code requirements for equipment grounding continuity
Positive bonding – Ensures continuous ground path through the coupling

Furnished Components

Each three-piece coupling is supplied complete with:

Threaded bushing – Internal and external threads
Sleeve – Internal threads for bushing engagement
Collar – Internal threads for conduit connection

Free-Fitting Threads

Easy assembly – Free-fitting threads ensure smooth installation
NPT thread standard – Compatible with standard rigid conduit and IMC

Specification	Details
Standard	UL 514B – Conduit, Tubing, and Cable Fittings
Material	316SS Stainless Steel
Finish	Vibration Polished
Thread Type	NPT (National Pipe Taper) – Straight Threads
Conduit Types	Rigid and IMC (Intermediate Metallic Conduit)
Raintight	Yes – Suitable for wet locations
Grounding	UL listed for grounding
Concrete-Tight	Suitable for concrete-encased applications
Trade Sizes	½" through 4"

Component	Material	Grade
Bushing	Stainless Steel	316SS
Sleeve	Stainless Steel	316SS
Collar	Stainless Steel	316SS

Applications

TSI three-piece couplings are essential for:

Industries Served

Food & Beverage Processing

Sanitary washdown environments

Chemical Processing Plants

Acid fumes and caustic environments

Wastewater Treatment Facilities

Moisture and chemical resistance

Marine & Offshore Installations

Saltwater and high-humidity conditions

Pharmaceutical Manufacturing

Clean rooms and hygienic zones

Pulp & Paper Mills

Corrosive process areas

Petrochemical Refineries

Hydrocarbon and chemical exposure

Refining & Extraction Sites

Harsh industrial environments

Complete System Availability

TSI INOX Conduits provides a comprehensive stainless steel conduit system:

Rigid Stainless Steel Conduit (RSSC) – UL 6A certified
Stainless Steel Rigid Couplings – Standard and three-piece configurations
Stainless Steel Three Piece Couplings – For non-rotatable conduit connections
Stainless Steel Rigid Nipples – Threaded both ends, various lengths
Stainless Steel Rigid Elbows – 90°, 60°, 45°, 30°, 22.5° bends
Stainless Steel Conduit Bodies – Complete range of configurations
Stainless Steel LT Conduit Connectors – Straight, 45°, and 90° configurations

Why Choose TSI INOX Conduits?

Uncompromising Quality

TSI INOX Conduits manufactures every three-piece coupling using premium 316 stainless steel and state-of-the-art production processes, ensuring consistent dimensions, accurate threading, and flawless vibration polished finishes in every product.

Global Supply

Based in India with a worldwide export network, TSI delivers stainless steel electrical conduit solutions to projects across North America, Europe, the Middle East, and beyond.

Technical Expertise

Our engineering team provides application assistance, code compliance guidance, and custom solutions to meet your exact project specifications—from material selection to installation best practices.

Industry Specialization

TSI INOX Conduits specializes in stainless steel conduit solutions for demanding industries, ensuring our products meet the unique requirements of each sector.

Ordering Information

Type

Three Piece Coupling

Material

316SS Stainless Steel

Finish

Vibration Polished

Thread Standard

NPT (National Pipe Taper)

Conduit Types

Rigid and IMC

Trade Sizes Available

½", ¾", 1", 1¼", 1½", 2", 2½", 3", 4"

Rating

Raintight, Concrete-Tight, UL Listed for Grounding

Stainless Steel Three Piece Coupling UL 514B