Straight Steel To Plastic Transition Fittings PE To Steel, Dn25 To Dn500

Straight PE-to-steel transition fittings for gas and water mains

A steel to plastic transition fitting is the joint where a PE100 gas main stops being plastic. Everything downstream of it - risers, meter sets, valve chambers, service connections - is steel, and something has to hand the pressure over without a leak path. The straight version does that with the fewest parts: an electrofusion PE socket on one end, a steel spigot sized to the DN series on the other, and a factory-made bond between them that does not depend on the weather on the day of installation.

Qingfa moulds the PE to steel transition fittings range in Yuyao, Zhejiang, in two wall series and 73 size pairings from dn25 up to dn500. Buyers searching for a steel to HDPE transition fitting in the UK, or for plastic to steel transition fittings for gas in the Gulf, are generally after this same part - the naming changes with the market, the geometry does not.

Straight range - PE socket and steel end pairings

73 size pairings in total: 52 in the SDR11 wall series and 21 in SDR17. SDR17 starts at dn90 because the thinner wall is not moulded below that size. Rows marked Yes can be supplied with a threaded steel end; the rest are welded or flanged.

Why a straight transition is the default choice

A straight transition is what you fit when the steelwork leaves the ground vertically in line with the main, or when the steel pipe continues on the same axis. There is no directional change to accommodate, so the fitting carries axial load rather than bending moment, and the electrofusion socket can be the full wall thickness of the main.

Two things decide the specification. First the wall series: the PE socket has to match the SDR of the main it is fused to, which is why the same steel DN appears in both the SDR11 and SDR17 rows. Second the steel end finish - a threaded end is only offered where the wall is thick enough to cut a sound thread, and the table marks those rows. Everything else is supplied for welding or with a flange.

Size coverage: what dn25 to dn500 actually means on site

The small end of the range, dn25 to dn63, exists because service connections in these sizes are still steel threaded at the meter, and a poly to steel transition fitting lets the utility fuse PE right up to the wall and cut the thread inside the factory instead of on site.

From dn90 upward the range follows the standard metric steel DN series rather than the PE series - PE dn110 pairs with DN89, DN108 or DN114 steel, and the buyer picks the one that matches the existing pipework. The largest pairing in the table is PE dn500 to DN529 steel, which is a transmission-sized joint rather than a service connection.

Size is not the only question buyers ask. The socket is an electrofusion transition fitting in the same sense as the rest of the PE100 range - a coil is embedded in the moulding and the fusion parameters travel with the barcode - so a crew that has already fused HDPE to steel transition fittings needs no new equipment. Where the project calls for the steel side to be welded, the spigot is supplied pre-machined to the DN outside diameter and ready for the welder.

Where straight transitions are installed

• PE distribution main to steel riser at the base of a meter installation
• Termination of an HDPE pipe run at a valve chamber or pressure-reducing station
• Transition into ductile iron, cast iron or carbon steel pipework in rehabilitation projects
• Service connection where the steel tail has to be threaded for a meter union
• Water main tie-ins on the SDR17 version, where the PE wall is thinner

How the two ends are made at Qingfa

The PE socket is injection moulded, then the steel spigot is machined, cleaned and inserted into a heated mould so the polymer is moulded onto the steel - not pressed or glued. The interface is a mechanical interlock formed while the PE is molten, which is why the joint holds under thermal cycling rather than relying on an adhesive.

Steel spigots are turned on CNC centres from bar or seamless tube, and the thread - where offered - is cut after turning so the axis stays concentric with the PE bore. Every batch is sampled for pull-out strength and checked dimensionally before it is released.

Inside the Yuyao plant

Zhejiang Qingfa Pipe Technology Co., Ltd. has made PE pipe fittings for gas and water networks for more than 25 years. The 35,000 m² plant runs 42 injection moulding machines, close to 50 high-precision CNC machining centres and more than 10 automated welding stations, with capacity of 10,000 tonnes of polyethylene fittings a year across dn20 to dn1200.

Resin is drawn from a central silo system, so every moulding run starts from the same dry material.

The moulding hall where the PE sockets for the straight range are produced.

Moulds for the dn25 to dn160 sockets running on a mid-size press.

The large press that moulds sockets above dn315, where wall thickness drives cycle time.

Heating-coil winding for the electrofusion sockets before they go into the mould.

CNC turning of the steel spigots and, where required, thread cutting.

Approvals held for the straight transition range

The straight range sits inside the same certification envelope as the rest of the PE100 fitting production: CE marking through ECM for dn20 to dn400 and a voluntary attestation to dn1200, plus the management-system certificates and the WRAS approval for potable water contact.

CE marking - ECM, dn20 to dn400
Issued by Ente Certificazione Macchine (ECM, Italy, notified body NB 1282). PE100 fittings for gas and water, dn20 to dn400, to BS EN 1555-3:2021 and BS EN 12201-3:2024.

CE - ECM voluntary attestation, dn20 to dn1200
ECM voluntary certification covering PE fittings dn20 to dn1200 to EN 12201-3:2024, EN 1555-3:2021 and Regulation (EU) No 305/2011.

CNAS laboratory accreditation - ISO/IEC 17025:2017
Accreditation of the Zhejiang Qingfa testing centre to ISO/IEC 17025:2017 under the CNAS-CL01 criteria.

ISO 9001:2015 - quality management system
Quality management system for the production and service of PE pipe fittings and PE ball valves; issued by Zhongjing Certification.

ISO 14001:2015 - environmental management system
Environmental management system for the production and service of PE pipe fittings and PE ball valves; issued by China Economic Certification.

ISO 45001:2018 - occupational health and safety
Occupational health and safety management system for production and service activities; issued by Zhongjing Certification.

WRAS material approval
UK approval for material in contact with drinking water: PE100 black HDPE fittings to BS 6920-1:2014, for water up to 65 °C.

GB/T 27922-2011 - five-star after-sales service
After-sales service system of the HDPE pipe fittings range evaluated to the GB/T 27922-2011 commodity after-sales service standard at five-star level.

Crating, marking and dispatch

Sockets are capped at both bores so the fusion surface cannot be scratched in transit. Crates are loaded so the steel ends carry no point load and the PE ends are never in contact with each other. Each fitting is marked with size, wall series, steel DN and batch number.

Finished PE fittings warehoused and staged for shipment at the Qingfa works

Buyer questions on the straight range

What sizes do you make?

dn25 to dn500 in SDR11, dn90 to dn500 in SDR17. The steel end is sized independently - tell us the existing steel DN and we match it.

Can the PE socket be fused by electrofusion on site?

Yes. The socket is a standard electrofusion socket with an embedded heating coil; the barcode and fusion parameters travel with the fitting so your installer can run it with any compliant control box.

What is the lead time and minimum order quantity?

Standard sizes ship from stock in Yuyao; non-standard steel DN pairings are made to order. Tell us the quantity and destination port and we will quote a lead time with the price - we are the manufacturer, not a trading house.

Do you supply samples and test reports?

A production sample can be sent for approval, and the fusion and dimensional test reports from our CNAS-accredited laboratory are released with every batch on request.

Who can quote me HDPE to steel transition fittings at factory price?

We can - we are a PE steel transition manufacturer in Zhejiang, China, and sell direct rather than through a trading company. Send your size list and we will return a factory quotation the same working week.

Which wall series should I order, SDR11 or SDR17?

Order the SDR that matches the main being fused to. A SDR17 socket will not fuse correctly onto a SDR11 pipe - the wall thickness and fusion parameters differ.

Is the threaded end available in every size?

No. Threading needs wall thickness, so it is offered only where the table marks it. Ask for the welded or flanged finish on the remaining sizes.

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