Chemical hoses

Chemical hoses – general information

Chemical hoses are intended for liquid chemicals both organic and inorganic (acids and bases, salt solutions, paints and varnishes, solvents, etc.) They are used for the transfer of chemicals in chemical processing, transfer and loading/unloading of liquid chemicals (e.g. tank trucks, rail tankers, IBC containers), for diverse technological processes in the chemical, food, pharmaceutical industry, for numerous other industrial processes but also in laboratories. The inner hose layer must be sufficiently resistant to chemical corrosion.
So as to select the right hose in terms of its chemical resistance, it is essential to gather the following data: type of medium (substance transferred by the hose), its state (e.g. liquid, gas), concentration and temperature of the substance, working pressure. The safety data sheet of a chemical substance is critical for the proper hose selection.  Check if there is a risk of static charges build-up, particularly for operation in a determined potentially explosive zone.
The principles of proper selection are given in the technical information section “Selection of hoses and fittings in regard to chemical resistance”  and in tables on chemical resistance of materials (see attachments and section TECHNICAL INFORMATION).

The inner layer of chemical hoses is usually made of EPDM or EPM rubber, Viton, polyamide, polyethylene UPE, fluoropolymers (PTFE, PFA, MFA, FEP). They are reinforced with textile cord or braid, if necessary, with steel wire helix in the case of suction delivery hoses.  The outer layer is made of rubber resistant to external factors.
Couplings and fittings intended for chemical hoses (see INDUSTRIAL FITTINGS) must be corrosion resistant the same as their sealing. The fittings are mounted using worm-drive clamps, bolt screw clamps or crimped with ferrules.
Other hoses suitable for the transfer of chemical substances are available in the following groups: general purpose hoses, food hoses, hoses for petroleum products, ducting hoses, composite and metal hoses, PTFE and silicone hoses, tubing for peristaltic pumps and Tygon tubing as well as in HIGH PRESSURE SECTION in thermoplastic hoses group.

Use of chemical hoses

The application of chemical hoses includes:

• unloading and loading chemicals of transport tanks (e.g. pallet containers, tanker trucks and rail tank cars) substancjami chemicznymi;
• processing in the chemical industry, food industry, pharmaceutical industry, cosmetics, biotechnology, etc.;
• filling and emptying packaging
• laboratories

Chemical hoses are used both as ready-made, complete flexible hoses with fittings, designed for a strictly defined medium, place of installation and operating parameters, as well as loose hoses, mounted on connections and stub pipes of technological equipment.

Hoses suitable for chemicals within a certain range

Hoses suitable for chemicals within a certain range are also in other chapters of INDUSTRIAL HOSES section.
These are in particular:

    Hoses for petroleum products – designed for petrochemicals: fuels, oils, hydrocarbons and their mixtures, crude oil, and liquid asphalt. Made of various materials: PVC hoses, nitrile rubber (NBR) hoses, hoses made of Viton or polyacrylate blends. Wide range of applications: from simple all-purpose hoses and fuel loading/unloading hoses to specialized hoses for crude oil extraction.
    PTFE hoses – hoses made of smooth or corrugated PTFE tube, with stainless steel or polymer fibre braid, often with a smooth silicone or other elastomer cover. They are resistant to almost all chemicals and relatively high temperatures due to the unique properties of PTFE. They enable the production of fully PTFE-lined, chemically resistant fittings. Commonly used in the chemical, petrochemical, food and pharmaceutical industries.
    Composite hoses – hoses formed of several layers of fabric and film of various thermoplastic materials wound between helically coiled outer and inner wires. The composition of fabric and film materials (polypropylene, polyamide, PTFE, ECTFE, etc.) provides resistance to fuels and chemicals. The hoses are very lightweight and extremely flexible. They are commonly used for chemicals and fuel loading/unloading operations in road and rail transportation and at ports.
    General-purpose hoses – made of PVC, polyurethane or rubber. For all-purpose use, for air, and water. Many of these hoses are suitable for light chemicals: diluted acids and bases, cooling fluids, cleaning agents, fertilizers, plant protection products, and sewage. Some of them can be used for fuels and oils. The hoses suitable for light chemicals are also in “Water and air hoses” section.
    Ducting and ventilation hoses – lightweight, flexible hoses, often in large diameters, intended for the extraction of gases, dust, and chips. This group includes chemically resistant hoses for the extraction of aggressive vapours and gases. They are generally manufactured from foil or impregnated fabrics, using chemically resistant materials: polyethylene, polypropylene, Viton, Hypalon, PTFE. Reinforced with steel wire helix or sheet metal helix.
    TYGON® and VERSILON™ tubing – a unique type of hoses made of improved PVC, elastomers and polymers. These are small-diameter, extruded hoses, without reinforcement or with braid, manufactured from the highest quality and purity materials, according to unique formulas, usually intended for small operating pressure. Used in laboratory technology, in peristaltic pumps and for dispensing products, including aggressive chemicals.

For high-pressure hoses for chemicals see HIGH PRESSURE section. Many low-pressure, non-reinforced, chemically-resistant polymeric hoses are also in PNEUMATICS section.

Classification of chemicals, safety data sheet, hazardous substances

When selecting a hose, it is important to identify the medium – the chemical substance conveyed by the hose, together with its properties and the hazards it poses. Chemical substances have their common names, chemical names and chemical formulas. The substance can be best identified by the classification (registration) number. There are many classification systems according to different regulations. The most universal is the CAS number, used throughout the world. Example:
substance name    chemical formula    CAS no.    REACH registration number    Index no.    EU no.
ethanol, ethyl alcohol, spirit, …    C2H5OH    64-17-5    01-2119457610-43-xxxx    603-002-00-5    200-578-6

A safety data sheet is one of the best sources of information about a chemical substance and its properties. The safety data sheet contains precise data on the composition of the chemical substance, its classification, physical and chemical properties, hazard identification, conditions for safe storage, transportation and much more. The safety data sheet (SDS) is required for all hazardous substances and those which are not subject to exemptions. Hazardous chemicals are classified according to types of hazards. One substance can pose several types of hazards. The types of hazards are designated by symbols and marked with pictograms according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS).
DESIGNATIONS OF HAZARDOUS SUBSTANCES ACCORDING TO GHS
chemical hoses - the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)    chemical hoses - the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)    chemical hoses - the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)    chemical hoses - the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)    chemical hoses - the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)    chemical hoses - the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)    chemical hoses - the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)    chemical hoses - the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)    chemical hoses - the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
explosive    flammable    oxidizing    toxic    health hazard    gas under pressure    corrosive    environmental hazard    toxic, irritant
hazardous substances according to the Pressure Equipment Directive (PED) 2014/68/EU    other substances according to the Pressure Equipment Directive (PED) 2014/68/EU

Special requirements for chemical hoses and hose assemblies in specific applications

Some special requirements may be set out for flexible hose assemblies in certain applications, particularly for the hose assemblies for chemicals. Loading/unloading and transportation of chemicals either in-plant or between industrial plants is a huge area of application for flexible hose assemblies. The transportation and loading/unloading of chemicals are governed by international regulations (ADR for road transport, and RID for rail transport). In addition to these regulations, countries also have separate regulations for the supervision of road and rail tankers, filling and emptying facilities and their equipment, including flexible hoses. In Poland, loading/unloading hose assemblies and filling and emptying equipment must meet the requirements of relevant regulations, and are supervised by Transportation Technical Supervision (TDT).

Impact of chemicals on a hose

phenomenon    description    effect – danger    prevention
CHEMICAL CORROSION    • hose material absorbs the medium and swells
• hose material dissolves in the medium
• hose material reacts with the medium
• additives are leached out    weakening of the hose, leaks, possible rupture    hose material suitable for the medium and time of exposure
STATIC CHARGES    due to the flow of the medium, electrostatic charges are created and accumulate in the hose wall    electric discharge (“spark”), ignition or explosion    hose made of antistatic or conductive materials – depending on the risk of occurrence and possible effect of the phenomenon
PERMEATION    medium (usually gaseous) permeates slowly through the hose wall to the outside or accumulates under the inner layer forming blisters    permeation of the hazardous medium (e.g., poisonous or explosive) to the outside or destruction of the hose by blisters    hose material and its construction with low permeability to the medium – depending on the risk of occurrence and possible effect of the phenomenon; pinpricking of the outer layer to avoid the formation of blisters

Chemical hose construction

    inner layer – material sufficiently resistant to chemical corrosion, e.g. EPDM, EPM, FKM, polyamide, UPE polyethylene, fluoropolymers (PTFE, PFA, MFA, FEP)
    reinforcement – cord or textile braid; steel helix (one or more) for suction-delivery hoses;
    outer layer – material resistant to external factors

Standards for chemical hoses

EN 12115 standard – covers the requirements for rubber and thermoplastic hoses and hose assemblies for liquid or gaseous chemicals. The standard distinguishes two types of hoses and hose assemblies intended for chemicals with working pressure up to 10 bar and temperature up to + 65ºC:

    Type D: delivery;
    Type SD: suction-delivery (vacuum up to 0.8 bar acc. to the standard ), and in terms of electrical properties, both types can be:
    M – electrically continuous (with copper wire)
    Ω – electrically conductive (conductive rubber; R ≤ 106 Ω)
    M/T – electrically continuous and with resistance through the hose wall R ≤ 109 Ω
    Ω/T – electrically conductive and with resistance through the hose wall R ≤ 109 Ω

The standard specifies a number of requirements for hoses and complete hose assemblies, including inner and outer diameter, minimum bend radius, marking, testing, etc. The safety factor for chemical hoses according to EN 12115 is at least 4 (i.e., for a maximum working pressure of 10 bar, the burst pressure is a minimum of 40 bar). The test pressure is 1.5 x working pressure. The standard specifies the materials of the inner layer: NBR, NR, IIR, EPDM, CSM or FKM (Viton) rubber, PE/UPE (polyethylene) thermoplastic polymer and fluoropolymers (e.g. PTFE, PFA, FEP). It also indicates (for reference) the chemical resistance of the materials according to CAS classification.
In addition to EN 12115 hoses, many types of hoses for chemicals meet only some of the requirements of the standard or are designed for different applications.
EN 16643 standard sets out specific requirements for non-bonded hoses and hose assemblies for liquid or gaseous chemicals with a fluoroplastic liner (e.g. PTFE), where the individual layers of the hose: inner layer, reinforcement (braid), outer layer are not closely joined (bonded, vulcanized) to each other. This design is typical for most PTFE hoses.

Products

• Chemical hoses
• Chemical hoses for light chemicals
• Teflon hoses
• Chemical hoses for medium aggressive chemicals
• Acid hose
• Chemical hoses for aggressive chemicals
• Chemical Teflon hoses
• Chemical hoses compliant with strict hygiene standards
• Chemical hoses for potentially explosive zones (ATEX)
• PTFE chemical hoses