Short answer
A length order must give a start and end reference along with the number. Fitting ends, sealing surfaces, elbow axes and bare hose ends can be different references. Unless the supplier and customer use the same reference, even two correctly measured products may turn out different.
Source: S024
Technical explanation
Although end-to-end measurement looks easy on an assembly with straight ends, the swivel nut and adapter geometry affect which surface is the reference. For elbow ends, the centerline or another point defined by the manufacturer may be used. The flexible section length also differs from the overall assembly length. Instead of carrying the length definition in one manufacturer's drawing over to another connection type as a default rule, the relevant assembly drawing should be read.
Source: S024
Topic-specific checkpoints
| Item | Description |
|---|---|
| Overall length | A–B references defined on the assembly. |
| Flexible length | Bendable hose section; separate from the rigid part of the fittings. |
| Cut length | Pre-production piece; derived from the manufacturer's assembly dimensions. |
| Tolerance | Required acceptance range and measurement method. |
Source: S024
How is it assessed in practice?
Name the A and B ends on the order drawing; tie the dimension arrows to the actual reference surface. State the tolerance and that the measurement is made in the unpressurized state and, if necessary, the installation condition. As an example, instead of writing '1500 mm' on a photo of an assembly with two elbows, prepare a simple drawing showing both the length dimension and the angle between the elbows. An estimate derived from photo perspective should not be used as an acceptance dimension.
Original editorial recommendation; not a clause of a standard.
Frequently asked questions
Is it enough to subtract the length of the two fittings from the overall length?
Not always. The portion of the hose inserted into the fitting and the manufacturer's cut length method matter. Base the calculation on approved assembly data; do not estimate it from the visible fitting length.
Source: S024
Source coverage
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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