The STAMPED Method: How to Choose the Right Hydraulic Hose
Reading time: approx. 6 minutes

Why choosing the right hose so often goes wrong

Replacing a hydraulic hose seems straightforward: you bring in the old one, ask for a new one in "the same size", and you're done. In practice, things go wrong more often than you'd think. The pressure rating doesn't match, the fitting leaks, or the hose fails far sooner than expected — not because the hose is defective, but because it isn't suited to that specific application.

The STAMPED method is a structured framework for making the right choice. It's an acronym that brings together seven selection criteria: Size, Temperature, Application, Medium, Pressure, Ends and Delivery. Together, they cover everything a hose needs to handle in real-world conditions.

Let's go through each one.

S — Size

The size of a hydraulic hose involves three parameters: inner diameter, outer diameter and length.

Inner diameter is by far the most important. It determines fluid flow rate. Too small, and flow velocity rises — leading to pressure drop, heat build-up and increased pump wear. Too large, and the system runs inefficiently and requires unnecessarily heavy components.

Hydraulic hose inner diameter is indicated using different conventions. The dash size -04 corresponds to 4/16" = ¼", -06 to 6/16" = 3/8", and so on, or in DN sizing (mm). This dimension is always printed on the hose itself, along with other technical data. If you're unsure how to read hose markings, refer to our dedicated article.

Outer diameter determines whether the hose physically fits in the installation: sufficient clearance for clamps, protective sleeves and cable trays. Length, finally, must be correct — neither under tension nor with excessive slack. It's worth factoring in a small margin for pressure contraction (hoses shorten slightly under high pressure).

T — Temperature

Every hydraulic hose has a working temperature range, both for the fluid inside and the ambient environment outside.

Standard hydraulic oil operates between -40°C and +100°C, but there are exceptions in practice: die-casting machines, steel mills, engine-adjacent installations, cold storage, or outdoor use in Nordic winters. A standard rubber hose typically has an inner tube of nitrile rubber, suitable for mineral oils up to approximately +100°C. For higher temperatures, PTFE (teflon) hoses are the solution.

Don't overlook ambient temperature either. A hose running alongside an exhaust pipe or above an oven requires a heat-resistant outer cover — regardless of the fluid temperature inside.

A — Application

This criterion covers the mechanical environment in which the hose operates.

Is the hose static, or does it move continuously? A hose on a hydraulic cylinder cycling hundreds of times per day demands a different bend radius than one that barely moves after installation.

There are also application-specific risks. On mobile machinery (crane trucks, combine harvesters, telescopic handlers), abrasion from contact with the frame or ground is a real concern. An abrasion-resistant outer cover or additional protection is required in these cases.

M — Medium

The inner tube of the hose must be chemically compatible with the fluid passing through it. This sounds obvious, but in practice it often goes wrong when a system is converted to a different fluid or when additives are introduced.

Mineral oil (the standard hydraulic fluid): compatible with nitrile rubber, by far the most widely used.

Fire-resistant fluids (HFA, HFB, HFC, HFD): used near heat sources or open flames. Each type has different requirements. HFD (synthetic esters) is aggressive towards many standard rubbers.

Environmentally friendly fluids (biodegradable oils of vegetable origin): increasingly used in agriculture and forestry. Not all hoses are compatible.

Water-glycol mixtures: used in certain cooling systems. Require specific inner tube materials.

CO₂ and N₂ (gas phase or mixed phase): an entirely different matter from hydraulic oil. Gas leaks are invisible and potentially dangerous. Specific standards apply to the hose, the fittings and the test procedure.

When in doubt, always consult the manufacturer's fluid compatibility chart.

P — Pressure

Pressure is the technical criterion where most mistakes are made, because working pressure, test pressure and burst pressure are three fundamentally different things.

Working pressure is the maximum pressure at which the hose may be used continuously. It is stated in the hose standard (e.g. EN 853 2SN or EN 856 4SP) and on the hose marking itself.

Test pressure is typically twice the working pressure. After assembly, this pressure is used to verify the integrity of the connection before the hose is put into service.

Burst pressure is the pressure at which the hose fails — typically four times the working pressure. This gives a safety factor of 4:1, as required by European standards.

Important: hydraulic systems experience pressure spikes. A pump starting or stopping abruptly, a valve closing quickly, a cylinder reaching end of stroke — all of these generate momentary pressure surges that can significantly exceed the nominal working pressure. Don't select a hose that just meets the working pressure; account for these peaks.

As a rule of thumb: the working pressure rating of the hose must be at least equal to the maximum system pressure including spikes.

E — Ends

The hose itself is only half of the assembly. The fitting determines the connection to the installation — and there are many ways this can go wrong.

First, the thread type. BSP, metric, JIC, ORFS, NPT: each has a different profile, a different pitch and a different sealing method. A BSP fitting in a metric-threaded port may seem to fit, but it will never seal properly. We've written a full article covering the most common thread types in hydraulics.

Second, the fitting family and crimping method. Depending on the hose type (braided or spiral) and the preferred technique (skive or no-skive), you'll select a different ferrule and fitting. These combinations are not interchangeable.

Third, orientation. Does the fitting need to be straight, or angled at 45° or 90°? This affects installation ease, space requirements and bending load on the hose.

D — Delivery

The D in STAMPED is sometimes interpreted as delivery lead time, but in the technical context it's broader: it refers to the final configuration and how the assembly must ultimately be delivered or applied.

What is the required length? Is additional protection needed (abrasion risk or high temperature near the ferrule)? Are hose clamps or mounting brackets required? Is a test report needed (traceability, CE documentation)?

In industry and on public contracts, it is increasingly common for a hose assembly to require full documentation: which hose, which fitting, which press, which crimp setting, when assembled. This demands a supplier who can provide that traceability.

STAMPED as a checklist

In practice, you don't need to fill in seven pages every time you order a hose. But when setting up a new installation, troubleshooting a hose that keeps failing, or switching fluid or pressure, it's worth working through each criterion.

Summary:

S — Inner diameter, outer diameter, length
T — Maximum fluid temperature, ambient temperature
A — Static or dynamic, abrasion risk, minimum bend radius, environment
M — Fluid type and chemical compatibility
P — Working pressure, pressure spikes, required safety factor
E — Thread type, fitting family, crimping method, orientation
D — Protection, documentation, traceability

Not sure? Ask us.

At Van de Calseyde Hydraulics, we help technicians and buyers select the right hose assembly every day. Whether you're replacing an existing hose or building a new installation: bring in the old hose or send us the technical data, and we'll help you make the right choice.