Composite hose is a multi-layer assembly of thermoplastic films and fabrics held between an inner and an outer wire helix, used to transfer petroleum products, solvents, chemicals and liquefied gases at typical working pressures of 7–14 bar. Most in-service failures trace back to specification errors, not manufacturing defects, the wrong liner film, an inner helix wire that is not compatible with the medium, or a missing vacuum or electrical-continuity requirement. This article walks through the pitfalls that catch procurement engineers, and gives you a checklist to close them before the purchase order goes out.
If you need the fundamentals of construction and layer design first, see the complete technical guide to composite hose; for a full parameter deep-dive, the composite hose specifications explained article covers pressure, temperature and bend-radius data in detail. This piece concentrates on what goes wrong at the specification stage.
Why is composite hose so easy to mis-specify?
Because two composite hoses that look identical from the outside can differ in every layer that matters. The liner film, the number of fabric plies, the inner and outer helix materials and the fitting attachment are all hidden inside the construction, and each one is a separate compatibility decision. A rubber hose has one tube compound to check; a composite hose has a film stack plus two metal wires, one of which is wetted by the medium.
That last point is the single most overlooked fact in composite hose procurement: the inner helix wire is in contact with the product. A galvanised carbon-steel inner wire is acceptable for petroleum duty, but in acid or wet chemical service it corrodes and the hose loses its structural core from the inside, invisibly. For aggressive media, specify a stainless steel (316) or polypropylene-coated inner wire, and write it on the order, because it is not implied by the liner choice.
Which standard and type applies, and what do the EN 13765 types actually mean?
EN 13765 is the European product standard for thermoplastic multi-layer (non-vulcanised) hoses and hose assemblies for the transfer of hydrocarbons, solvents and chemicals. It defines four types by duty, and misreading them is a classic specification error, because the types are graded by service severity, not by liner chemistry:
| EN 13765 type | Intended duty | Typical note |
|---|---|---|
| Type 1 | Vapour transfer only (e.g. vapour return lines) | Not for liquid transfer |
| Type 2 | Liquid transfer, standard duty (petroleum products, many solvents) | The common tanker/terminal hose |
| Type 3 | Liquid transfer, aggressive chemical duty | Full chemical-resistant film stack (e.g. PTFE/PVDF films) |
| Type 4 | Heavy duty, e.g. ship-to-shore transfer | Highest mechanical demands |
A frequent and dangerous mix-up: ordering a Type 1 hose for a liquid line because it is the cheapest item on the quotation. Type 1 is a vapour hose and is not rated for liquid transfer.
For liquefied gases, EN 13766 governs multi-layer hoses for LPG and LNG transfer, with additional low-temperature flexibility and pressure-cycling requirements. Do not order an EN 13765 hydrocarbon hose for LPG duty, the standards, test regimes and low-temperature ratings differ.
Working pressures under EN 13765 are typically in the 7–14 bar range depending on type, bore and construction, with burst pressure at a minimum multiple of working pressure defined per type (at least 4:1). Two rules apply on top of the standard: the working pressure is quoted at 20 °C and derates at elevated temperature, and the rating for a given hose family is not one number, always read the pressure for the specific DN and type from the manufacturer's datasheet.
What are the most common composite hose specification pitfalls?
1. Liner film assumed, not confirmed. Polypropylene film handles petroleum products and many solvents; polyamide films extend the range; PTFE or PVDF film stacks are needed for aggressive chemicals. "Chemical composite hose" on a purchase order is meaningless, state the exact medium, concentration and temperature and let the manufacturer confirm the film stack in writing.
2. Inner helix wire ignored. As above: the wetted wire must be compatible with the medium. Galvanised steel for fuels; stainless or coated wire for chemicals. If the medium is corrosive to zinc, a galvanised inner wire will fail long before the film does.
3. Vacuum duty not declared. Composite hoses used on tanker discharge or stripping duty see partial vacuum. Vacuum resistance depends on helix gauge and pitch and must be specified explicitly; a hose that is fine at +10 bar can flatten at −0.5 bar if it was not built for suction.
4. Electrical continuity assumed. For flammable media and ATEX 2014/34/EU zoned areas, the assembly must be electrically conductive end-to-end, in a composite hose this depends on the helices being properly terminated into both end fittings. Electrical resistance is verified by measurement in accordance with ISO 8031, and the test should be repeated at every periodic inspection, because a corroded or disturbed wire termination silently breaks continuity. (Note: the cover-abrasion standard sometimes miscited in this context, ISO 6945, has nothing to do with electrical properties.)
5. Temperature treated as independent of pressure. The catalogue temperature range and the catalogue working pressure are not simultaneously available at the extremes. Ask for the derating curve.
6. End fittings under-specified. Composite hose ends are built up on the hose by the manufacturer, typically swaged ferrule constructions with flanged (EN 1092-1 / ASME B16.5), threaded, or cam-and-groove terminations. Camlock couplings to EN 14420-7 are common on tanker composite hoses and are correct for liquid duty, never for compressed air or gases. Specify the fitting material (carbon steel, 316 stainless, aluminium, brass) against both the medium and the external environment, and require an assembly test certificate: each assembly should be hydrostatically proof-tested (typically at 1.5 × working pressure) and carry a unique serial number.
7. No service-life or inspection policy. Composite hoses in terminal duty are typically inspected visually and electrically at least every 12 months, pressure-retested periodically per site policy, and retired on a fixed calendar limit regardless of appearance. Agree the regime before the hose enters service, not after the first audit finding.
What must be on the purchase order? The 10-point checklist
- Medium, exact chemical name, concentration, contaminants; manufacturer's written compatibility confirmation for the film stack and both helix wires.
- EN 13765 type (1–4) or EN 13766 for LPG/LNG, matched to duty, not price.
- Working pressure at operating temperature, including surge; request the derating curve.
- Vacuum rating, state the required negative pressure explicitly if the hose will see suction.
- Bore (DN) and length, keep flow velocity moderate (≈3 m/s for aggressive chemicals, ≈5 m/s for petroleum) to limit erosion and static generation.
- Minimum bend radius vs. installation geometry, composite hose is flexible, but violating the minimum bend radius kinks the helix permanently; fit elbows or swivels where routing is tight.
- End fittings, type, standard (EN 1092-1, EN 14420-7 camlock for liquids, threaded), material, and orientation.
- Electrical continuity, required resistance, verified per ISO 8031, with certificate.
- Certificates, assembly serial number, hydrostatic test certificate, declaration of conformity; for food duty, food-contact documentation for the specific liner film and medium (for plastics films, Regulation 10/2011/EU applies; note it covers plastics only).
- Inspection and retirement policy, interval, retest pressure, calendar limit.
A completed checklist attached to the RFQ is the fastest way to an accurate quotation. Browse the industrial hoses category or go straight to composite hose products to compare constructions, and check the technical catalogues for dimension and pressure tables.
Where do composite hoses fail in service, and what does that teach specifiers?
The dominant field failure modes map directly onto the pitfalls above. End-fitting pull-out points to a damaged or overloaded assembly, or tensile installation without slack, composite hose must never be pulled taut between fixed points; allow roughly 10 % slack. Inner wire corrosion points to a wire/medium mismatch. Kinking and permanent helix deformation point to bend-radius violations or vehicles driving over unprotected hose. Loss of electrical continuity points to fitting-termination corrosion, which is exactly why the ISO 8031 measurement is repeated at every inspection, not just at delivery.
One economic note: composite hose typically costs more per metre than a general-purpose rubber hose of the same bore, but in solvent and chemical transfer it commonly outlasts rubber several times over, and its low weight (often 30–40 % less than rubber of the same DN) reduces manual-handling effort at tanker bays. The premium disappears the first time a correctly specified assembly survives a duty that would have destroyed a cheaper hose. For a structured comparison, see rubber hose vs composite hose, and for the full ordering criteria list, the composite hose selection article.
Get the specification verified before you order
Tubes International Capital Group stocks composite hoses for petroleum, chemical and gas duties together with the matching couplings and flanges, see industrial fittings for termination options across the range. Send us your medium, pressure, temperature and end-connection data via the RFQ form: our engineering team selects the hose and fittings, builds the assembly and pressure-tests it before dispatch, with full test documentation for your hose register.