PE100 Socket Fusion Coupling - dn20 to dn63, SDR11

热熔承插直接 · SDR 11 · socket fusion coupling · COUP

What a coupling does that no other fitting in this range does

A coupling is the only fitting in this range that asks nothing of the flow. It does not step the bore down, it does not branch it and it does not turn it, so a run made entirely of couplings behaves as one continuous pipe with a ring of fused material every six metres. That is why this is the part that gets ordered by the box on a distribution job while the tees and elbows are ordered by the piece.

The one thing a coupling does change is how many joints you make. Every pipe length needs one, so a coupling count is a joint count, and the joint count is what decides how long the laying gang takes and how much of the testing schedule you have to budget for. On a domestic service the couplings are the small line item; on a mains extension they are the majority of the fusion work.

The moulded body, and why the socket is tapered

A sleeve with a stop in the middle

The body is a plain cylinder with a socket cut into each end and a shoulder left standing in the centre. That shoulder is doing two jobs: it stops the first pipe end from travelling past the middle, and it leaves a solid ring of material for both sockets to be moulded around. Because the stop is moulded rather than machined, its position is fixed by the mould and not by anyone at the bench.

The taper is what makes the joint work

Neither socket is a straight bore. Each one narrows slightly from the mouth to the root, so the pipe end is squeezed against the socket wall as it is pushed home. The melt has nowhere to go except backwards into the bead, and the same taper is what lets a hand push a dn63 pipe end into place in the seconds available before the surface cools. A parallel socket would either seize before it was home, or be loose enough to leave a gap at the root.

Unpigmented black, moulded in one shot

The body is injection moulded in one operation from the same PE100 compound used for the pipe, so there is no interface between two materials to be concerned about. It is supplied black and unpigmented, which means no colour stripe and nothing painted on. The size and the wall series are moulded into the outside wall during the same shot, so they cannot come off in handling.

Six diameters, one wall series

The range runs dn20 to dn63 in stepped diameters, and every one of them is SDR11. There is no SDR17 variant of this fitting and no second wall series to choose between. That removes a decision a specifier would otherwise have to make, and it also means the part number is nothing more than the diameter: state dn32 and the wall series is already settled.

A coupling must match the pipe it joins on both sides. Pipe is bought as a diameter plus a wall series, and a coupling made for SDR11 has a socket dimensioned for the outside diameter of SDR11 pipe. Pairing it with a heavier or lighter wall pipe from a different series is not a tolerance question, it is the wrong fitting, and the joint will show it at the first pressure test.

Coupling schedule

The schedule below reproduces the published sizes for this fitting exactly as they are held in the product list. Every entry is SDR11 and every entry is a straight coupling.

What the drawing controls and what it leaves open

A drawing is the only place where a socket stops being a description and becomes something a mould shop can be held to. The coupling is controlled on six figures: the outside diameter at each end, the socket bore at the mouth and again at the root, the insertion depth that each pipe end must reach, and the overall length of the body.

The tight figures are the two socket bores and the diameter at the socket end, held to plus or minus two or three tenths of a millimetre. That is not fussiness: the bore sets how much the pipe is compressed and therefore how much melt is displaced into the bead, and a bore that is a few tenths out will either refuse the pipe or leave the root dry. The looser figures are the outside diameters and the overall length, where a millimetre of variation changes nothing about whether the joint holds.

The full dimension schedule for the coupling is on the range page, together with the tolerance on each figure and a note on what each one controls on site.

Two heated ends, one push, no shim

In principle a coupling is the easiest joint in the range to make, because both ends are the same size and the technique does not change from one to the other: heat both socket walls and both pipe ends, then push. In practice this is the fitting where the two-sided nature is most often fumbled, because it is tempting to heat one end, seat it, and only then deal with the second.

• Cut both pipe ends square and chamfer them before anything is heated. A square cut is what lets the end reach the stop.
• Mark the insertion depth on both pipe ends while the fitting is still in the box. Once the heater is in play there is no time to go looking for a tape.
• Heat the coupling on the heater so that both sockets are warmed in the same pass, and heat both pipe ends while it is there.
• Push the first pipe end to its mark, then bring the second end in and push it to its mark. Both ends must be seated before anything starts to stiffen.
• Hold both ends still while the joint sets. Moving one end to fix the other is the usual way a coupling joint ends up with a dry root on one side.

On this size range the whole operation is a two-hand job with a push fit, and no clamping frame is needed. On larger diameters the same sequence is used with a hydraulic rig, which is a different product family and a different set of equipment.

Socket fittings in this size band are injection moulded, one cavity per shot.

How a coupling joint is judged sound

A sound coupling shows the same two signs at both ends. The bead should be continuous all the way round each socket mouth, with an even height and no flat spot where the melt has escaped. Underneath it, the witness line marked on each pipe before the push should now sit flush with the face of the fitting on that side.

It is worth checking the two ends separately rather than treating the joint as one thing. A coupling that looks right on the near socket and has a thin bead on the far one has been made by heating unevenly or by pushing one end late, and the far socket is the one that will fail a test. Where a joint is critical, a fusion joint strength test is run in our own laboratory against the batch, which converts the judgement into a number.

Ordering a coupling without a drawing

A coupling is the one fitting in this range that can be ordered from a single figure. There is no second dimension to state, no thread to specify and no angle to choose, so the order line is the diameter and a quantity.

Two things are worth adding anyway. Name the medium, gas or water, because that decides the certification pack that travels with the goods. And name the pipe wall series you are joining, so the sockets can be confirmed against your pipe before the box is sealed rather than after it is on site. Send a size list and we will come back with a schedule that mirrors it, one line per diameter.

Cartons are labelled by fitting type, size and SDR series.

Manufacturer details

ECM Type Approval certificate 1N240805.PTSQC86

Issued to: PTS Tech Solutions Sdn Bhd, Malaysia

HDPE electrofusion and butt fusion fittings, DN20–DN400, including elbows. Standards BS EN 1555-3:2021, BS EN 12201-3/-4:2024.

Valid to: 04 Aug 2029

ECM Attestation 1N241120.ZQPSW72

Issued to: Zhejiang Qingfa Pipe Technology Co., Ltd.

PE pipe fittings DN20–DN1200. Issued under a non-notified procedure and expressly for markets outside the EU.

Valid to: 19 Nov 2029

WRAS material approval 251155041

Issued to: Zhejiang Qingfa Pipe Technology Co., Ltd.

PE100 black injection moulded fittings for contact with wholesome water, up to 65 °C. Machined sizes fall outside this scope.

Valid to: Nov 2030

CNAS-accredited test data

Issued to: Own test laboratory

Coil resistance, fusion joint strength and dimensional checks, reported per batch on request.

Valid to: per batch

Buyer questions about the coupling

Where to send a size list

Send a size list and the medium and we will return a quoted schedule mirroring it, with the certification pack attached. For a first order, the quickest route is to state the pipe diameters and the wall series you are working in and leave the rest to us.

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