Pipe Loop — Companion Article
1. What this tool does
Pipe Loop sizes a symmetrical U-loop from the same guided-cantilever length as Pipe Leg. The calculation runs in the browser. It does not call the Engineering API.
2. When to use it
Use it when a designer is sketching a loop that takes the growth of one run. The result is preliminary. It is not a flexibility analysis.
3. Inputs
Enter the run, the temperatures or the expansion, the outside diameter, E, and Sa.
4. How it works
The running tool is the calculation. The relations already written for version 1.0.0 are:
Δ = α × run length × temperature difference
L = sqrt(3 × E × D × Δ / Sa)
W + 2H = L
The source named on the page is the guided cantilever method, M.W. Kellogg, Design of Piping Systems. The page takes L as the straight developed length of the loop. The usual proportion is height twice the width, so W = L/5 and H = 2L/5. Two other rows keep that same developed length and only change the proportion. Those rows are layout options, not extra code requirements. Elbow arc length is not included.
Assumptions stated on the page: anchors at both ends of the run, guides so the growth goes into the loop, and no friction.
5. Understanding the result
Read the developed length W + 2H, then the three proportions: height twice the width, height equal to width, and width twice the height.
The two proportions other than height twice the width are layout options. They are not extra code requirements. Elbow arcs are not included.
6. Engineering considerations
No catalogue facts are read. Anchors, guides, and no friction are assumed. The page does not name a code edition. This article does not add one.
The developed-length form is the one the page says is published for thermal expansion loops.
7. Example
Same basis as the pipe-leg run on 3 October 2026: NPS 6 Sch 40 carbon steel, outside diameter 168.3 mm, operating 150°C, install 20°C (temperature difference 130°C), α 12.0×10⁻⁶ /°C, E 203000 MPa, Sa 207 MPa, run 30 m. The figures were hand-checked. They were not re-run for this remap.
Developed length W + 2H = 4813.8 mm. Elbow arcs are not included.
- Height twice the width: W 962.761 mm, H 1925.52 mm.
- Height equal to width: 1604.6 mm each.
- Width twice the height: W 2406.9 mm, H 1203.45 mm.
8. Standards/references (licensed vs interim)
No catalogue facts are read. The method citation is M.W. Kellogg, Design of Piping Systems, as the page states. The developed-length form is the one the page says is published for thermal expansion loops. This article does not name a code edition. The page does not name one.
This draft does not class that citation as licensed standards data or as interim owner-authorised data. The interim pattern in the owner decisions log is ASME B36.10-2022 Table 2-1. This tool does not use that table. Owner engineering review confirms the source classification before publish.
9. Limitations/disclaimer
- The result is preliminary and needs engineering review. It is not a flexibility analysis.
- Elbow arc length is not included.
- The two proportions other than height twice the width are layout options. They are not extra code requirements.
- Anchors, guides, and no friction are assumed.
A member check is not an engineering fact. The note is under Repository notes.
10. Use the tool
Calculate now: Pipe Loop
Shortcode: Preliminary. This result needs engineering review before anyone uses it. It is a symmetrical U-loop sketch, not a flexibility analysis. Δ = α × Lrun × ΔT L = sqrt(3 × E × D × Δ / Sa) W + 2H = L The leg length is the guided cantilever method, M.W. Kellogg, Design of Piping Systems, and standard piping textbooks. This page takes that length as the straight developed length of a symmetrical U-loop, W + 2H. That developed-length form is the one published for thermal expansion loops. The usual proportion with that form is height twice the width, so W = L/5 and H = 2L/5. The other two rows keep the same developed length and only change the proportion. They are layout options, not extra code requirements. Elbow arc length is not included. Assumptions: anchors at both ends of the run, guides so the growth goes into the loop, and no friction. The loop is in one plane. E and Sa are the values you enter. A typical modulus is a near-ambient textbook figure, not a code allowable, and it is not adjusted for temperature. The coefficient must use the same degree as the temperature difference. The page does not convert the coefficient when you change that degree. Pipe Loop version 1.0.0 This records your check of the tool output. It does not change the tool or the engineering data. . Version 1.0.0. Re-check this article when the tool version changes.Pipe loop
Formula
Check this tool
How this calculation works: companion path TBD.
That return link is not on the tool page. This draft does not add it. The public article path is TBD because this file is not published.
The article stays public if the tool is restricted. A visitor with no entitlement sees a lock message on the tool, not a bare “Access denied”. The copy is in the Companion Article standard. This draft does not place that lock on the page and does not mark the tool free, Pro, or Enterprise.
Related tools
Pipe Leg, at /tools-training/pipe-leg/, is the guided-cantilever leg page. This page uses that same length for a symmetrical U-loop. It is a different page.