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An expansion loop absorbs thermal changes in length through the elastic deformation of the pipe itself and so reduces the forces caused by restraint.
A straight pipe between two anchors cannot expand; it builds up high compressive forces instead. An expansion loop gives the line a detour perpendicular to the direction of expansion. The change in length of the straight run bends the legs of this detour – and a pipe accepts bending far more readily than compression.
The loop is made of the same pipe as the line. It has no moving parts, produces no pressure thrust and needs no maintenance.
The longer the legs perpendicular to the direction of expansion, the softer the loop. The relationship is not linear: for a leg restrained against rotation at both ends, the bending stress for a given displacement falls with the square of the leg length, and the force on the anchors with the cube.
A leg one quarter longer therefore nearly halves the force. Conversely, a larger pipe diameter is stiffer – large sizes need considerably larger loops than small ones. The exact design is done by pipe stress analysis, because the elbows themselves are flexible and bring their own stress intensification.
An expansion loop works between two anchors and is best placed midway between them; both sides then share the movement. Guides keep the straight runs in line and direct the expansion into the loop.
The distance from the first guide to the loop is critical. If it sits too close, it prevents the leg from deflecting and the loop loses its effect. Supports within the loop itself must not block the movement either – sliding supports belong there, not guides.
A horizontal loop in the plane of the pipe needs area but drains continuously. A vertical loop saves floor space but forms a high or low point: gas collects at the top, condensate at the bottom. In steam and condensate lines every vertical loop therefore raises the question of drainage and venting.
An expansion loop rarely fails – but it often performs worse than planned.
What Entracon offers here is on the matching page.
See what we offer| Form | Configuration | Typical use |
|---|---|---|
| L-bend | One change of direction; one leg absorbs the expansion of the other | Corners that exist in the routing anyway |
| Z-bend | Two changes of direction with an offset | Lines that sidestep an obstacle |
| U-loop | Four elbows forming a loop | Long straight runs, for example on pipe racks |
Whenever the space is available, almost always: it has the pressure strength of the pipe, no limited cycle life and no pressure thrust. The expansion joint is the answer for tight spaces, large diameters at low pressure and very sensitive connections.
That depends on the expansion, the pipe diameter, the material and the allowable anchor forces. Rules of thumb and charts give a first size; the verification is done by pipe stress analysis.
Yes, through the additional elbows and the longer line. In most lines the share is small; with tightly sized pumps or two-phase flow it should be checked.
Yes. If the line is installed shortened by part of the expected expansion, the forces in the operating condition fall. The stress range that matters for fatigue remains the same.
One short conversation usually settles more than three quotations. Call or write — you will reach an engineer directly.
Start typing – for example “balancer”, “SAP” or “pipe stress”.
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