PE100 Socket Fusion 45 Degree Elbow, Dn63
PE100 Socket Fusion 45 Degree Elbow - dn20 to dn63, SDR11
热熔承插45°弯头 · SDR 11 · socket fusion 45 degree elbow · ELBOW
The 45 body and the geometry of a shallow turn
A shallow bend moulded as one piece
A 45 degree elbow is a single moulded body in which the two socket mouths sit at 135 degrees to each other. That is the whole geometry: the run enters through one socket, leaves through the other, and turns a quarter of a right angle on the way. There is no insert, no liner and no welded joint at the bend, because the sweep is formed in the same shot as the two sockets.
Why the bore is not circular at the bend
The channel through the middle of a bent fitting cannot be a circle at every station, because the inner radius is shorter than the outer radius. On this body the wall is compensated so that the inner side of the sweep is thicker than the outer, which keeps the bore substantially round where the flow is fastest. A moulded elbow that ignored this would have a thin inner wall and would be the first place a pressure spike showed itself.
The shallow turn is gentler on the flow
A turn of 45 degrees disturbs the flow far less than a right angle does. The head loss through this fitting is a fraction of that through a 90 degree elbow of the same bore, so on a long main the two fittings are not interchangeable on hydraulics even where the geometry could be made to work either way. That is the reason a designer who has the trench space will always prefer the shallower pair.
Six sizes on the same body
Six diameters are held for this fitting, running from dn20 to dn63, and all six are the same SDR11 series as the pipe. The body shape does not change across the range, only its scale does, so the same barcode and the same handling notes apply to a dn20 as to a dn63.
Because the part number carries no angle, the angle has to be settled before ordering: a 45 is not a 90 with a different label. Both are held in the same six diameters, so the range will not save anyone from choosing the wrong one at the desk.
45 degree elbow schedule
The table below is the published size list for the 45 degree elbow and is reproduced from the product record without alteration. Every line is SDR11 and every line is a body with a 45 degree sweep.
| Size | SDR series |
|---|---|
| dn20 | 11 |
| dn25 | 11 |
| dn32 | 11 |
| dn40 | 11 |
| dn50 | 11 |
| dn63 | 11 |
Getting a quarter turn with two fittings
The job of this fitting in a gas network is to deliver a change of direction that the pipe itself cannot. PE pipe is supplied straight and only bends to a generous radius, so wherever a route has to turn more sharply than the pipe will allow, a fitting has to make up the difference. A 45 degree elbow handles the shallow turns, and it does so without the concentration of stress that a sharper fitting would create at the same point.
The other thing it does is allow a turn to be built in two easy steps. Two 45s separated by a short length of pipe produce a 90 degree change of direction, and that arrangement is kinder to the pipe than a single right angle because the load is shared between two joints and the intermediate straight length absorbs some of the movement.
When 45 degrees is the right angle and when it is not
The question is not which angle is better but which the route needs. Where the pipe can follow a long curve and the objective is simply to avoid an obstacle, 45 degrees is usually enough and the shallower fitting costs less in head loss. Where the route has to turn squarely, a pair of 45s set a pipe length apart gives the same result with two joints instead of one.
- Choose a single 45 where the change of direction is genuinely shallow and the trench can carry a gentle sweep.
- Choose two 45s where the route turns a full right angle but there is room for a short straight between them.
- Choose a single 90 where space is tight and the extra joint cannot be accommodated.
- Never mix the two in one turn unless the geometry has been set out, because a 45 and a 90 do not add up to the angle the eye expects.
The decision also has a cost side. Two 45s mean two joints to make, two joints to test and one more length of pipe to cut. On a short service that is negligible; on a main where fusion time is the limiting factor it tips the balance towards the single fitting.
Setting out a two-elbow turn
Making the joint is the same operation as any other socket fusion connection in this range. The difference lies in the setting out rather than the fusion, because the two ends of a bent body have to line up with two pieces of pipe that are not in line with each other.
- Cut and chamfer both pipe ends square, and mark the insertion depth on each.
- Dry assemble the elbow against both pipe ends before heating anything, so that the final orientation is known rather than guessed.
- Heat both sockets and both pipe ends in the same pass on the heater.
- Push the first end to its mark, then bring the second pipe into line and push it home, turning the body only if the mark allows it.
- Hold both ends while the joint sets. A bent body will try to rotate as the melt cools, so the two pipe lengths have to be restrained, not just the fitting.
Where two 45s are used to make a right angle, set the intermediate pipe length before either fitting is fused. The short piece between them is a cut length that cannot be adjusted afterwards, so it is measured out on the ground rather than in the trench.
Socket fittings in this size band are injection moulded, one cavity per shot.
Changes of direction in a trench with limited width
The commonest place to meet this fitting is a trench that has to dodge something. A service crossing under a wall, a main stepping around a culvert, a riser easing towards a meter box: these are all shallow turns where a 45 is the natural answer and a right angle would either not fit or would put an unnecessary kink in the flow.
The second place is at the top of a rising main, where a ductile connection has to be brought into alignment with a horizontal run. Two 45s let the pipe arrive at the surface at an angle the ground allows and then be brought square, without a single sharp corner in the plastic.
Checking a swept turnover
A fused bend is checked on the two beads and on the alignment. Both beads should be continuous around their socket mouths, and the two pipe lengths should come away in line with the sockets rather than strained into them. On a swept turn the second check matters more than usual, because a pipe that has been forced into line will show a wedge-shaped gap at one side of the bead before the joint has even cooled.
Where a run has been made up from a pair of 45s, the intermediate length should be checked against the setting-out drawing. A short piece that has been cut long or short will pull the two elbows out of the intended angle, and the error shows up much later as a misaligned branch or a riser that will not meet its spigot.
Manufacturer details
| Company | Zhejiang Qingfa Pipe Technology Co., Ltd. |
| Registered name | 浙江庆发管业科技有限公司 |
| Business line | PE100 / PE80 gas and water pipe, butt fusion and socket fusion fittings |
| Works address | No. 288, Da'an Road, Jiande, Hangzhou, Zhejiang, China |
| Website | www.qingfaindustry.com |
Buyer questions about the 45 degree elbow
Ordering a pair, not a single
Ordering this part takes a diameter and a quantity, plus one word of disambiguation: 45. The angle is not carried by the size, so an order that states only dn32 will be queried before it is picked, which is the right outcome but costs a day.
Where a turn is being built from a pair, say so on the order. A note that the fittings are for a two-elbow sweep tells us the parts will be used together and lets us check they are drawn from the same batch, which matters when the two joints will be tested as one assembly. Send the size list and we will return a schedule that mirrors it.
Cartons are labelled by fitting type, size and SDR series.
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