Description

Product Overview

A PP square duct 90° elbow is an injection-moulded polypropylene fitting that turns a rectangular PP duct run through 90° in one corner. It is the fitting used where square ductwork changes direction – along walls, across ceilings or around obstacles – and it is custom-made to match the dimensions of the rectangular duct sections it connects to.

The elbow is injection moulded in PP or flame retardant PPs, in beige or grey, and joins the duct run by hot air welding, with socket connection reinforcement at the joint. Because each elbow is made to order, dimensions, wall thickness and corner radius are confirmed with the project before production. For the straight duct this elbow connects to, see Polypropylene Rectangular Ducts.

A square duct elbow is one part of a ventilation system: it changes the direction of the run rather than connecting or branching it, and matching fittings are available from the same supplier so a complete PP duct line can be specified from one source.

Product Selection Summary

Good Fit

• Turning a rectangular PP duct run through 90° at a wall or ceiling corner
• Routing square ductwork around obstacles, columns or equipment
• Building long main lines that follow the building structure
• Projects needing flame retardant fittings for part or all of a run

Conditions To Confirm

• Rectangular duct section dimensions (width, height) for the custom elbow
• Material grade: PP or flame retardant PPs
• Gas composition, concentration, temperature and moisture at the operating point
• Whether the run needs removable access at the change of direction (use flanges there instead)

Not a Replacement For

• Fans, airflow balancing devices, flexible connectors or gas treatment equipment

Technical Specifications

Confirmed Product Parameters

Parameter	Value
Product Type	PP Square Duct 90° Elbow (rectangular duct elbow)
Material	PP (polypropylene) or PPs flame retardant grade
Angle	90°
Size Range	Customized per project – rectangular duct sections
Connection	Hot air weld; socket connection reinforcement
Fabrication	Injection molding
Color	Beige / Grey
Working Temperature	-15℃ to 80℃
Chemical Resistance	pH 1-14 (acid and alkali)
Certification	ISO9001, ISO14001, RoHS

Because this elbow is made to order, there is no standard size list: the width and height of the duct section, the corner radius and the quantity are confirmed per project before production.

Material & Performance

Because square fittings are injection moulded rather than welded from sheet, the elbow keeps the same corrosion resistance as the welded duct while offering consistent moulded dimensions, smooth surfaces and a shorter production time for standard profiles.

PP square duct elbows are injection moulded from polypropylene, chosen for corrosive fume handling in ductwork:

• Acid and alkali resistance: PP withstands corrosion by high-concentration acids and alkalis across a wide pH range (pH 1-14).
• Sound insulation: PP reduces vibration and noise transmitted through the fitting.
• Light weight: moulded PP fittings are light and easy to handle and weld on site.
• Consistent moulded dimensions: each elbow is produced to a standard mould, giving uniform dimensions and wall thickness.
• Long service life: PP duct systems offer a service life of up to 50 years under specified operating conditions.
• Anti-condensation: PP conducts heat poorly, reducing condensation and heat loss at the fitting.

Flame retardant PPs is available where fire-rated ductwork is required; specify the required flame retardant grade when inquiring. The material grade applies to the whole fitting, so a single grade can be specified across the duct, fittings and accessories in the run.

Applications

90° Direction Changes in Rectangular Systems

Square duct elbows are used at the points where a rectangular duct run changes direction by 90°:

• Wall and ceiling corners – turning the run to follow the building structure
• Obstacle bypass – routing around columns, beams and equipment
• Main line routing – changing the direction of long square mains
• Branch take-offs – connecting a branch line at right angles to the main

Each elbow adds one corner to the run. Because the fitting is made to the same section size as the duct, the change of direction keeps one continuous cross-section, and the joint is sealed by the same hot air welding used for the rest of the square duct run.

Selection Notes & Quotation Information

Square or Round Elbow?

A square duct elbow is used in rectangular duct systems and is custom-made to match the duct section. A round PP elbow is a standard moulded fitting used in round duct systems, with 17 standard sizes from φ20mm to φ500mm. Choose the square elbow where the system uses rectangular duct, typically for space-efficient runs along walls and ceilings; choose the round elbow where the run uses round duct with standard sections.

To Quote PP Square Duct 90° Elbow

Provide: rectangular duct section dimensions (width and height), quantity, material grade (PP or flame retardant PPs), color (beige or grey), application, destination port, and your duct schedule or drawings.

MOQ and lead time are confirmed per project. Request a quote via WhatsApp or email using the contact block below.

Installation & System Integration

PP square duct elbows are joined to the duct run by hot air welding, and each joint is reinforced with a socket connection. The same joining method applies to straight square duct and other rectangular fittings, so the run is welded and sealed as one continuous system.

Because the elbow is made to order, its dimensions are confirmed against your duct schedule before production, so the fitting arrives sized to the run and is welded on site with the same tools used for the straight sections.

Complete systems combine square elbows with rectangular duct, tees and reducers. See the full range of PP duct systems.

Related Products

• Polypropylene Rectangular Ducts
• PP Square Duct
• PP 90° Elbow
• PP Air Duct Tee
• PP Concentric Reducer
• Full PP Duct Range
• PP Air Duct Guide – a complete guide to PP duct types, sizes and materials.

FAQ

What is a PP square duct 90° elbow?

It is an injection-moulded polypropylene fitting that turns a rectangular PP duct run through 90° in one corner, used where square ductwork changes direction along walls, across ceilings or around obstacles.

What sizes are available?

The elbow is custom-made to match your rectangular duct section dimensions – width and height are confirmed per project, so there is no standard size list.

Square or round elbow – which should I choose?

A square duct elbow is used in rectangular duct systems and is custom-made to match the duct section. A round PP elbow is a standard fitting used in round duct systems with 17 standard sizes.

How is it connected?

By hot air welding to the duct sections, with socket connection reinforcement at the joint – the same method used for straight square duct and other rectangular fittings.

Is flame retardant PP available?

Yes. The elbow is available in standard PP or flame retardant PPs; specify the required flame retardant grade when inquiring.

What do I need to provide for a quote?

Rectangular duct section dimensions (width and height), quantity, material grade, color, application, destination port, and your duct schedule or drawings.