Updated: 2 September 2026
Hydraulic Hose Layline Explained: How to Read Hose Markings, Sizes & Pressure Ratings
A hydraulic hose layline is the printed identification information running along the outside cover of the hose.
It can help identify the hose manufacturer, product series, nominal size, working pressure, applicable standard and other manufacturing information.
When a hydraulic hose needs replacing, the layline is often one of the quickest and most useful sources of identification information — but it should not be used in isolation.
The replacement hose must also be checked for fitting type, connection size, pressure capability, fluid compatibility, routing, temperature and machine requirements.
For a broader guide to hydraulic hose construction and selection, see our hydraulic hoses comprehensive guide.
Quick Answer:
What does a hydraulic hose layline tell you? Depending on the manufacturer and hose series, the layline can show the manufacturer, hose family, nominal bore or DN size, applicable SAE or EN standard, working pressure and production or batch information. It is a useful identification tool when selecting a replacement hose.
What Is a Hydraulic Hose Layline?
The layline is the printed text, numbers and symbols applied along the hydraulic hose outer cover.
It provides information that helps distinguish one hose specification from another.
A layline may contain:
- Manufacturer or brand
- Product or hose series
- Nominal hose size
- Dash size
- DN size
- SAE specification
- EN or other applicable standard
- Working-pressure rating
- Pressure units such as PSI, bar or MPa
- Manufacturing or batch information
- Approvals or additional application markings where relevant
Important
A layline helps identify the hose — it does not identify the complete hose assembly. The end fittings, thread type, sealing method, orientation, hose length and routing must also be confirmed before replacement.
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Check Your Oil NowCommon Hydraulic Hose Layline Markings
| Layline Marking | What It Usually Indicates | Why It Matters |
|---|---|---|
| Manufacturer | The company that produced the hose | Helps identify the correct manufacturer’s hose data |
| Hose Series | The manufacturer’s product family or hose type | Helps identify construction, pressure capability and compatible couplings |
| Dash Size | Common nominal hose-bore designation | Helps identify hose internal diameter |
| DN | Nominal diameter designation | Provides another size reference |
| SAE / EN Standard | Applicable hose construction or performance standard | Helps confirm the intended hose specification |
| WP | Working pressure | Shows the published normal operating pressure capability for that hose specification |
| PSI / bar / MPa | Pressure measurement units | Allows the hose rating to be compared with the system requirement |
| Batch / Date Code | Production or traceability information | Can help identify manufacture or traceability details |
Example Hydraulic Hose Layline
A hydraulic hose may carry a layline similar to:
ALFAGOMMA DIN EN 853 2SN DN12 SAE 100R2AT 1/2" WP 330 BAR
This example could be interpreted as follows:
- ALFAGOMMA – manufacturer
- DIN EN 853 – referenced European standard
- 2SN – hose construction/type designation
- DN12 – nominal diameter designation
- SAE 100R2AT – referenced SAE specification
- 1/2" – nominal hose bore
- WP 330 BAR – published working-pressure marking for the specific hose shown
Do Not Treat Example Markings as Universal
The exact wording, pressure rating and layout vary by manufacturer, hose series and size. Always use the markings on the actual hose and check them against the manufacturer’s current technical data.
What Does DN Mean on Hydraulic Hose?
DN means nominal diameter.
It is a metric-style designation used to indicate the approximate nominal bore size of a hose or pipe.
For example, a hose marked DN12 is associated with a nominal bore around 12 mm and may correspond to a common 1/2-inch hydraulic hose size, depending on the hose specification.
For a full size comparison, see our hydraulic hose sizes guide.
What Does WP Mean on a Hydraulic Hose?
WP usually means working pressure.
This is the published maximum working-pressure value associated with that hose specification under the manufacturer’s stated conditions.
It should not be confused with burst pressure.
See our hydraulic hose pressure ratings guide for a detailed explanation of working pressure, burst pressure, PSI, bar and MPa.
What Do SAE and EN Markings Mean?
Hydraulic hose laylines may include references to recognised standards or specifications.
These can indicate construction and performance requirements associated with the hose type.
Examples commonly encountered in hydraulic hose identification include:
- SAE 100R1
- SAE 100R2
- EN 853
- EN 856
- EN 857
The standard marking is useful, but the full hose series and manufacturer data should still be checked because individual products can have additional characteristics or ratings.
Why Hydraulic Hose Layline Markings Matter
A replacement hydraulic hose should not be selected simply because it looks similar to the failed hose.
Two hoses with similar outside diameters may differ in:
- Internal diameter
- Reinforcement
- Working pressure
- Temperature capability
- Fluid compatibility
- Bend radius
- Compatible coupling system
Reading the layline helps narrow down the correct hose specification before the replacement assembly is produced.
Can You Identify the Hydraulic Fitting From the Layline?
No — not reliably.
The layline primarily identifies the hose itself. The connection at each end of the assembly must be identified separately.
Common hydraulic fitting families include:
- BSP
- JIC
- ORFS
- Metric
- Flange connections
The fitting also needs to be checked for:
- Thread size
- Male or female connection
- Seat type
- Sealing method
- Fitting orientation
See our hydraulic hose fittings guide for more information.
What If the Hydraulic Hose Layline Has Worn Away?
Laylines often become difficult to read due to age, abrasion, dirt, paint or environmental exposure.
If the marking is unreadable, further identification may be needed.
This can include checking:
- Internal hose bore
- Outside diameter
- Hose construction where identifiable
- Fitting type
- Thread size
- Machine specification
- Hydraulic circuit requirements
- Working pressure
- Routing and bend requirements
Useful Identification Tip
Before removing an old hose, take clear photographs of the hose layline, both end fittings, routing, connection points and orientation. That information can make replacement identification much easier.
Can You Replace a Hydraulic Hose Using Only the Layline?
No. The layline is an important starting point, but a complete replacement requires more information.
Before producing or installing a replacement hose assembly, confirm:
- Hose series and size
- Working pressure
- Fluid compatibility
- Temperature requirements
- Fitting type and thread
- Fitting orientation
- Overall hose length
- Minimum bend radius
- Routing
- Machine movement
Hose Identification Is More Than Reading a Number
A correct replacement hose assembly combines the right hose specification with compatible couplings, the correct end connections, correct length and suitable installation. Matching only the layline is not enough.
How to Read a Hydraulic Hose Layline Step by Step
01 — FIND THE MANUFACTURER
Identify the brand so you can refer to the correct hose technical information.
02 — IDENTIFY THE HOSE SERIES
Find the product family or construction designation.
03 — CHECK THE SIZE
Look for dash size, DN or nominal bore information.
04 — CHECK PRESSURE & STANDARD
Identify any working-pressure marking and applicable SAE, EN or other specification.
05 — CHECK THE COMPLETE ASSEMBLY
Identify the fittings, length, orientation, routing and machine requirements before ordering the replacement.
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Related Hydraulic Hose Guides
- How to Measure a Hydraulic Hose
- Hydraulic Hose Sizes Explained
- Hydraulic Hose Pressure Ratings Explained
- Hydraulic Hose Fittings Explained
- Hydraulic Hose Bend Radius Explained
- Hydraulic Hose Routing Guide
- Hydraulic Hose Protection Guide
Need Help Reading a Hydraulic Hose Layline?
Send us clear photographs of the hose markings, fittings and machine connection points, or speak to Completely Hydraulic for hose identification and replacement support.
Hydraulic Hose Layline FAQs
What is a hydraulic hose layline?
A hydraulic hose layline is the printed identification information running along the hose outer cover. It can show the manufacturer, hose series, size, working pressure, standard and production information.
What does DN mean on a hydraulic hose?
DN means nominal diameter. It is a nominal metric size designation that helps identify the hose bore.
What does WP mean on a hydraulic hose?
WP normally means working pressure. It indicates the published working-pressure capability of that specific hose series and size under the manufacturer’s stated conditions.
What does SAE mean on a hydraulic hose?
SAE markings refer to hose specifications or standards commonly used to identify hydraulic hose construction and performance requirements.
What does EN mean on a hydraulic hose?
EN markings identify a European standard associated with the hose construction or performance specification. The manufacturer’s actual hose data should still be checked.
Can I replace a hydraulic hose using the layline only?
No. The layline identifies the hose, but the replacement also requires confirmation of fittings, thread type, length, orientation, pressure requirements, routing, fluid compatibility and machine conditions.
What if the hydraulic hose layline is unreadable?
The hose can still be identified using its bore, construction, fittings, thread sizes, machine information and hydraulic requirements. Where there is uncertainty, a hydraulic hose specialist should confirm the specification.
Does the hydraulic hose layline show the fitting type?
Usually not. The layline primarily identifies the hose itself. BSP, JIC, ORFS, Metric and other fitting connections must normally be identified separately.