Short answer
On a hose with two elbows, the orientation of the ends relative to each other is an order detail as important as the length. If it is not clearly defined from which end and from which viewing direction the angle is measured, the same number can produce different assemblies.
Technical explanation
A hose assembly must fit into place without twisting. If the relative angle of the two elbows is wrong, the hose may be installed by forcibly turning it and the load may be transferred to the body. The viewing direction and clockwise convention used in the manufacturer's drawing must govern. The angle of a single end and the relative orientation between two ends are not the same information. The plus/minus angle convention of one system should not automatically be assumed to be the same in another system.
Topic-specific checkpoints
| Item | Description |
|---|---|
| Reference end | A/B identification |
| Viewing direction | Clear arrow or view on the drawing |
| Angle | Relative orientation and sign convention used |
| Acceptance | Orientation check separate from length |
How is it assessed in practice?
On the order drawing, choose end A as the reference and show the viewing direction with an arrow. Specify the rotation of end B relative to this reference; do not write only '90 degrees'. Adding a dimensioned photo or a simple 3D view when the sample is prepared reduces misunderstanding. At acceptance, check length and orientation separately. If the assembly only fits when forced on site, do not count it as an accepted orientation; compare the drawing with the actual port positions. If the revision changes, do not silently overwrite the angle of the previous order.
Original editorial recommendation; not a clause of a standard.
Frequently asked questions
Is it enough to write only 90° for two elbows?
It is not enough. The reference end, viewing direction and measurement convention must also be stated.
Source coverage
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S017
Parker Safety Guide, Publication 4400-B.1 Parker Hannifin · accessed 2026-10-20 PDF page 3; 3.7 Minimum Bend Radius, 3.8 Twist Angle and Orientation and 3.13 Routing | PDF page 3; 3.1 Component Inspection, 3.2 Hose and Fitting Assembly and 3.3 Related Accessories
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S024
Hose and Flexible Tubing, MS-01-180 Swagelok · accessed 2026-10-19 PDF pages 4–5 / printed 253–254: Nomenclature; pages 8–9: selection, installation and use