Safety Guidelines for Using Steam Hoses and Fittings

Rachel Stevens

August 20, 2025

Safety Guidelines for Using Steam Hoses and Fittings

Steam is indispensable for a range of industries. Its high energy density makes it effective, but also inherently hazardous if not handled correctly. A single failure in a steam hose or fitting can cause scalding injuries, equipment damage or costly downtime. For this reason, safety needs to be considered long before steam is allowed to flow through a system.

In the UK and Europe, there are two guidelines that govern the standards around this subject: BS EN ISO 6134, which specifies requirements for rubber steam hoses, and the EU’s Pressure Equipment Directive (PED) 2014/68/EU.

Understanding these guidelines is important for anyone using steam hoses and fittings, so let’s look at both and see how to translate them into day-to-day practice. Keep reading to learn more…

The significance of safety in steam

But first, let’s discuss why safety matters.

A hose must be able to withstand both the maximum operating pressure and temperature of the steam it will carry. Exceeding these limits, be it by pump surges, pressure spikes, or superheated conditions, can lead to catastrophic failure.

Beyond the physical risk of rupture, the wrong hose can degrade rapidly under repeated thermal cycling (variation in temperatures that create internal stresses). Materials that lack resistance to steam embrittlement or swelling will develop micro-cracks, leading to leaks or bursts further down the line.

In safety-critical processes such as pharmaceutical sterilisation or chemical plant operations, even minor steam leakage can compromise a sterile environment or ignite combustible atmospheres, which can prove costly to human and product safety.

When materials falter under prolonged exposure to steam, microscopic pinholes can open, releasing high-velocity jets of scalding steam. Operators cleaning or inspecting equipment are particularly vulnerable to such invisible threats.

Beyond the immediate safety risk, undetected leaks lead to inefficiencies. Steam loss drives up energy consumption, diminishes system performance, and inflates operating costs.

And beyond the safety and performance concerns, failure to adhere to recognised standards also attracts regulatory penalties. Insurers, and health and safety regulators, typically demand evidence of compliance with ISO or European directives. Poor documentation or use of non-certified hoses may void warranties and insurance cover, exposing organisations to financial and legal repercussions.

The best course of action is to learn about the standards and guidelines. Let’s take an overview of these two pivotal standards.

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BS EN ISO 6134

BS EN ISO 6134 is the benchmark for rubber steam hoses and hose assemblies that convey saturated steam and condensate.

These specifications cover everything from classification and materials to performance testing, so that hoses remain safe and reliable under demanding steam conditions.

Scope and classification

BS EN ISO 6134 divides steam hoses into two pressure–temperature types, each tailored to specific duty cycles:

Type	Maximum working pressure	Maximum temperature
1	6 bar (87 psi)	Up to 164 °C (327 °F)
2	18 bar (261 psi)	Up to 210 °C (410 °F)

Within each type, hoses are further grouped by cover resistance:

Class A: non-oil-resistant cover

For general steam heating or humidification, where oil contact is minimal.
Prone to softening, swelling and tearing if exposed to oils or hydrocarbons.
Typically delivers longer life in dry-service applications.

Class B: oil-resistant cover

Engineered to resist petroleum-based contaminants without degradation.
Rated up to 207 °C (406 °F) for saturated steam, 232 °C (450 °F) for superheated steam.
Ideal for chemical, petrochemical, and refinery environments.

Hoses can be electrically bonded (marked “M”) or electrically conductive (marked “Ω”), preventing static build-up and allowing for safe dissipation of any charge.

Materials and construction

A compliant steam hose must comprise three essential layers:

Tube
Reinforcement layer
Cover

We cover the specifics of this in our article How to Choose the Best Steam Hose & Fittings for Your Needs which will provide more information on the subject; but, the key thing to remember is that each component must be manufactured under strict quality controls.

Performance requirements and testing

To validate a steam hose’s fitness for duty, BS EN ISO 6134 mandates a number of tests.

Below is a table of the physical properties of finished hoses:

Property	Unit	Requirements	Test method
Min burst pressure	–	10x max working pressure	ISO 1402
Proof test pressure	–	No leakage or distortion at 5x max working pressure	ISO 1402
Min adhesion between components	kN/m	2,4	ISO 8033
Min bending test (under no pressure)	T/D	0,8	ISO 10619-1:2011, method C1
Change in length at proof test pressure	%	-3 to +8	ISO 1402
Max change in twist at proof test pressure	°/m	10	ISO 1402
Ozone resistance of the cover	–	No cracking observed under x2 magnification	ISO 7326:2006; method 3, relative humidity (55 ± 10) %, ozone concentration (50 ± 5) × 10−9, elongation 20 %, temperature 40 °C

There are some additional tests for physical properties of finished hose assemblies, which are:

Property	Unit	Requirements	Test method
Proof test pressure	–	No leakage or distortion at 5x max working pressure	ISO 1402
Electrical resistance	Ω	≤ 102 /assembly for M-type ≤10^6 /assembly and ≤10^9 resistance between lining and cover for Ω-type	ISO 8031:2009, method 4 ISO 8031:2009, method
Short-term steam test	—	Clause 10	Clause 10
Long-term steam test	—	Clause 10	Clause 10

Resistance to steam (ISO 4023:2009, Method B): this can be split into both the short-term and long-term.

Short-term: 7 cycles of 20 h steam on/4 h off (168 h total).
Long-term: 30 cycles of 20 h steam on/4 h off (720 h total).
Post-test criteria include no leakage, no lining cracks or blisters, and cover free from damage.

Below are the permissible changes in properties after the short-term test.

Property	Type 1	Type 2
Max reduction in actual burst pressure	25%	10%
Max reduction in lining elongation	50%	50%
Min elongation at break of lining	150%	150%
Max lining hardness increase in IRHD	10	10

Flexing after steam exposure: hose must bend without developing cracks, and its electrical resistance must remain within limits.

Additional considerations

Superheated steam: service life declines if hoses are exposed to superheated steam. Therefore, you must always verify temperature ratings.
Popcorning: inner-lining blisters can form when trapped condensate flashes to steam. To prevent this, you must blow dry hoses after each use, and use extruded, gas-tight liners rather than wrapped constructions.
Rusting inlays: steel inlays can corrode if steam contacts a porous inner wall. Where corrosion risk is high, specify galvanised or stainless-steel reinforcement.
Fittings: quick-release couplings are prohibited under pressure. Always use threaded or bolted fittings designed for in-service tightening. Make sure that fittings match hose type, pressure rating and electrical bonding requirements.

BS EN ISO 6134 exists to set a standard for which all rubber hoses should adhere to. Doing so can dramatically reduce the likelihood of incident, and extend the service life of your hoses and systems.

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Pressure Equipment Directive (PED) 2014/68/EU

The PED aims to bring harmony to pressure equipment requirements across the EU. The directive applies to:

New pressure equipment and assemblies with a maximum allowable pressure (PS) > 0.5 bar.
Assemblies designed and marketed as integrated functional units.
Equipment supplied new or second-hand from third (non-EU) countries.

It excludes on-site user assembly under non-manufacturer responsibility, focusing on market availability rather than industrial installations under end-user control.

The PED deliberately excludes items governed by other directives or deemed low-risk due to their design or use case.

Exclusions include:

Pipelines beyond the last isolation device within installations.
Water networks and hydroelectric headrace equipment.
Simple pressure vessels under Directive 2014/29/EU.
Aerosol dispensers (Directive 75/324/EEC).
Vehicle-related equipment covered by transport regulations.
Pressure equipment in categories only requiring sound engineering practice.
Nuclear-specific equipment and well-control devices.
Engines, compressors, pumps, and items where pressure is not a principal design factor.
Flexible casings, silencers and carbonated-drink containers.
Heating radiators and low-pressure heating pipes.

Key definitions

Understanding the PED requires clarity on several foundational terms.

Pressure equipment: vessels, piping, safety and pressure accessories, including attached elements.
Piping: pipes, tubing, fittings and hoses designed to convey fluids in a pressure system.
Safety accessories: devices such as safety valves and pressure switches that protect against excessive pressure.
Pressure accessories: components with an operational role that also bear pressure.
Assemblies: manufacturer-assembled units of multiple pressure equipment items marketed as a single product.
Maximum allowable pressure (PS): the highest pressure for which equipment is designed.
Fluids: these include Group 1: Hazardous substances (e.g., explosives, toxic, flammable) or those where operating temperature exceeds flashpoint; or Group 2: Non-hazardous fluids.

Safety requirements

Annex I of the PED sets out Essential Safety Requirements (ESR), mandating that manufacturers assess hazards and implement appropriate measures.

Provisions include:

General: eliminate or reduce risks as far as reasonably practicable, and inform users of any residual risk.
Design: account for pressures, temperatures, traffic, wind, seismic loads, corrosion, fatigue, and instability of fluids.
Safe handling and operation: prevent dangerous discharge, restrict access during pressurisation, and control surface temperatures.
Examination, draining and venting: ensure safe maintenance by preventing water hammer, vacuum collapse, and uncontrolled reactions.
Corrosion and wear: provide material allowances, liners or replaceable parts where harsh conditions may occur.
Overpressure protection: fit safety accessories or monitoring devices, ensuring independence, fail-safe operation and redundancy.
External fire: design to limit damage in the event of fire exposure.

Manufacturing procedures must provide quality design, defect-free component preparation, qualified execution of permanent joints and non-destructive testing, all under appropriate certification. Traceability of pressure-resisting materials is compulsory.

Each equipment item then undergoes final inspection and a proof test (typically hydrostatic to assess the structural integrity and leak tightness), with assemblies additionally checked for correct safety device function.

Conformity assessment

Pressure equipment is classified into categories I–IV based on hazard level, fluid group, pressure, volume and nominal size. Conformity modules include:

Module A: internal production control.
Module B: type examination.
Module C–G: varying levels of production and design quality assurance.
Module H1: full quality assurance with design examination.

Below is a deeper understanding of each module:

Module	Description	Key responsibilities
A: Internal Production Control	Manufacturer declares conformity on their sole responsibility based on internal production control.	Establish technical documentation covering design, manufacture, operation, risk assessment, standards applied, design calculations, and test reports.
A2: Internal Production Control Plus Supervised Pressure Equipment Checks at Random Intervals	Manufacturer declares conformity on their sole responsibility, supplemented by random supervised checks by a Notified Body.	Establish technical documentation. Ensure manufacturing process compliance. Perform final assessment of equipment.
B: EU-Type Examination – Production Type	Notified Body examines technical design and verifies conformity through technical documentation and examination of a specimen representative of production.	Lodge application with a single Notified Body. Application includes manufacturer details, declaration of no other applications, technical documentation, and specimens.
B: EU-Type Examination – Design Type	Notified Body examines technical design and verifies conformity through technical documentation without examination of a specimen. Experimental design method not allowed.	Lodge application with a single Notified Body. Application includes manufacturer details, declaration of no other applications, and technical documentation.
C2: Conformity to Type Based on Internal Production Control Plus Supervised Pressure Equipment Checks at Random Intervals	Manufacturer declares conformity to an EU-type examination certificate and Directive requirements, supplemented by random supervised checks by a Notified Body.	Ensure manufacturing conformity with the approved type and Directive requirements. Perform final assessment.
D: Conformity to Type Based on Quality Assurance of the Production Process	Manufacturer ensures conformity to an EU-type examination certificate and Directive requirements by operating an approved quality system for production, final product inspection, and testing, subject to surveillance.	Operate an approved quality system. Lodge application for quality system assessment with a Notified Body. Maintain the approved quality system.
D1: Quality Assurance of the Production Process	Manufacturer declares conformity to Directive requirements by operating an approved quality system for production, final product inspection, and testing, subject to surveillance.	Establish and keep technical documentation for 10 years. Operate an approved quality system. Lodge application for quality system assessment. Maintain the approved quality system.
E: Conformity to Type Based on Pressure Equipment Quality Assurance	Manufacturer ensures conformity to an EU-type examination certificate and Directive requirements by operating an approved quality system for final product inspection and testing, subject to surveillance.	Operate an approved quality system for final inspection and testing. Lodge application for quality system assessment. Maintain the approved quality system.
E1: Quality Assurance of Final Pressure Equipment Inspection and Testing	Manufacturer declares conformity to Directive requirements by operating an approved quality system for final product inspection and testing, subject to surveillance.	Establish and keep technical documentation for 10 years. Operate an approved quality system for final inspection and testing. Lodge application for quality system assessment. Maintain the approved quality system.
F: Conformity to Type Based on Pressure Equipment Verification	Manufacturer ensures conformity to an EU-type examination certificate and Directive requirements, with verification by a Notified Body through examination and testing of every product.	Ensure manufacturing conformity with the approved type and Directive requirements.
G: Conformity Based on Unit Verification	Manufacturer declares conformity to Directive requirements, with verification by a Notified Body on an individual unit basis.	Establish and make technical documentation available to the Notified Body and keep it for 10 years.
H: Conformity Based on Full Quality Assurance	Manufacturer declares conformity to Directive requirements by operating an approved quality system for design, manufacture, final product inspection, and testing, subject to surveillance.	Operate an approved quality system covering design, manufacturing, final inspection, and testing. Lodge application for quality system assessment. Provide technical documentation for one model of each type. Maintain the approved quality system.
H1: Conformity Based on Full Quality Assurance Plus Design Examination	Manufacturer declares conformity to Directive requirements based on an approved full quality assurance system (design, manufacturing, testing) with an additional design examination and special surveillance of the final assessment by a Notified Body.	Operate an approved quality system. Lodge application for quality system assessment and provide technical documentation for one model of each type. Maintain the approved quality system. Keep NB informed of changes to the quality system and approved design.

Manufacturers choose a module appropriate to their equipment’s category or opt for a higher one to demonstrate additional compliance. They must compile technical documentation, draft an EU Declaration of Conformity and affix the CE marking visibly and indelibly.

For categories II–IV, the notified body’s identification number accompanies the CE mark. Equipment falling below certain thresholds relies on sound engineering practice rather than CE marking.

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Find quality steam hoses and fittings at The Hosemaster

At The Hosemaster, we stock all the steam hoses and fittings you’ll need for your steam-related needs. We have decades of experience within the hose industry, which means you not only have access to superb supplies, but also expert advice when you require it.

If you have any further questions, you can get in touch with our team online, or give us a call on 01282 604 002.