Description

Product Overview

A PP 45 degree elbow is an injection-moulded polypropylene duct fitting that turns a ventilation run through a gradual 45 degrees. It is used where a PP duct route changes direction gently – along long duct lines, around obstructions or between sections of a run – and it matches the round PP duct range from φ20mm to φ500mm.

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. Being a moulded fitting, each size has consistent dimensions and wall thickness across batches. For the straight duct that the elbow connects to, see Polypropylene Round Ducts.

A duct elbow is one part of a ventilation system: it connects to straight duct, flanges, couplings and other fittings rather than replacing them, 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

• PP duct runs that need a gentle 45° direction change along the route
• Longer duct lines where a gradual turn keeps flow resistance lower
• Corrosive exhaust and ventilation systems using the round PP duct range
• Projects needing flame retardant fittings for part or all of a run

Conditions To Confirm

• Duct diameter (φ20mm to φ500mm, 17 standard sizes) and quantity
• Material grade: PP or flame retardant PPs
• Available straight-line distance for the gradual turn
• Gas composition, concentration, temperature and moisture at the operating point

Not a Replacement For

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

Technical Specifications

Confirmed Product Parameters

Parameter	Value
Product Type	PP 45° Elbow (polypropylene duct elbow)
Material	PP (polypropylene) or PPs flame retardant grade
Size Range	φ20-500mm – 17 standard sizes
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

Available Sizes (φ)

Diameter	Diameter
φ20mm	φ160mm
φ25mm	φ200mm
φ32mm	φ250mm
φ40mm	φ315mm
φ50mm	φ355mm
φ63mm	φ400mm
φ75mm	φ450mm
φ90mm	φ500mm
φ110mm

Material & Performance

Because round 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 internal surfaces and a shorter production time for standard sizes.

PP 45 degree 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 caused by air flow through the turn.
• Light weight: moulded PP fittings are light and easy to handle and weld on site.
• Consistent moulded dimensions: each size is produced to a standard mould, giving uniform dimensions and wall thickness across batches.
• 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.

Applications

PP 45 degree elbows are used wherever a round PP duct run changes direction gradually:

• Long duct routes – adjusting direction along ceiling and wall runs without a sharp turn
• Obstruction bypass – stepping the duct line around beams, pipes and columns
• Slope and level changes – small angle adjustments along the run profile
• Exhaust and ventilation systems – the same fitting serves laboratory, workshop and chemical exhaust runs built from round PP duct

Where space is tight and a sharp turn is unavoidable, a PP 90° elbow changes direction in less length – see Selection Notes below.

Two 45° elbows can also be used in place of a single 90° turn, splitting the change of direction into two gentler bends. This spreads the turn over more duct length and is a common layout where the run must change direction but a single sharp elbow would put excessive stress on the joint or disturb the airflow.

Selection Notes & Quotation Information

45° or 90°?

A 45° elbow turns more gradually than a 90° elbow and generally creates less flow resistance over the change of direction, but it needs more straight-line distance to complete the turn. Use a 45° elbow where the route allows a gentle bend and lower resistance matters; use a 90° elbow where space is tight and the turn must be sharp. Both join the duct by the same hot air welding method.

How to Size the Elbow

Match the elbow to the outside diameter of the straight PP duct it connects to – the elbow size should equal the duct diameter at the joint. If the run changes diameter at the turn, combine the elbow with a reducer on the smaller side so both ends weld to matching diameters.

To Quote PP 45 Degree Elbow

Provide: duct diameter (φ20-500mm), 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 45 degree elbows are joined to the duct run by hot air welding, and the joint is reinforced with a socket connection. The same joining method applies to straight duct, tees and reducers, so a run can be welded and sealed as one continuous system.

Where a run will be disassembled later for maintenance, flange connections are used at those points instead, so the elbow can be bolted between flanged sections.

Complete systems combine elbows with straight duct, tees, couplings and flanges. See the full range of PP duct systems.

Related Products

• Polypropylene Round Ducts
• PP 90° Elbow
• PP Air Duct Tee
• PP Air Duct Flange
• PP Air Duct Coupling
• Full PP Duct Range
• PP Air Duct Guide – a complete guide to PP duct types, sizes and materials.

FAQ

What is a PP 45 degree elbow?

It is an injection-moulded polypropylene duct fitting that turns a round PP duct run through a gradual 45 degrees, used where a duct route changes direction gently.

What sizes are available?

17 standard sizes from φ20mm to φ500mm: φ20, φ25, φ32, φ40, φ50, φ63, φ75, φ90, φ110, φ160, φ200, φ250, φ315, φ355, φ400, φ450 and φ500mm.

45° or 90° – which should I choose?

A 45° elbow turns more gradually with generally lower flow resistance but needs more straight-line distance. A 90° elbow turns in the shortest length, suited to tight spaces.

How is it connected?

By hot air welding to the duct run, with socket connection reinforcement at the joint – the same method used for straight duct and other round 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?

Duct diameter, quantity, material grade, color, application, destination port, and your duct schedule or drawings.