BS 4089:1989 download.Specification for Hoses and hose assemblies for liquefied petroleum gas.
1.1 Scope
BS 4089 specifies requirements for the design, construction, inspection and testing of hoses and hose assemblies used for the transfer of liquefied petroleum gas (LPG) (see 1.2.15) under pressure or refrigerated.
Section 2 specifies requirements for four types of rubber hose and six types of hose assembly, two types of which are available as electrically continuous or electrically discontinuous hose assemblies. Section 3 specifies requirements for composite hose assemblies. Section 4 specifies requirements for flexible metallic hose assemblies.
NOTE 1 Appendix A gives recommendations on the packing and storage of hoses.
NOTE 2 Appendix B gives the type number equivalents for rubber hoses and hose assemblies specified in BS 4089:1989 and BS 4089:1966.
NOTE 3 The titles of the publications referred to in this standard are listed on the inside back cover.
1.2 Definitions
For the purposes of this standard the following definitions apply.
1.2.1
tube
a plain uncorrugated metal cylinder which may be processed during manufacture to become flexible metallic hose
1.2.2
flexible metallic hose
the flexible leak-tight metal element of a flexible metallic hose assembly without fittings or covering
1.2.3
braid
a layer (or layers) of cylindrically woven wires covering the hose and attached to the flexible metallic hose ends and fittings, serving the functions of:
a) restraining the hose against elongation; and b) damping vibration of the hose.
1.2.4
flexible metallic hose assembly
a flexible metallic hose with end fittings attached, complete with braid and/or covering, if required ready for service
2.2.5 Type 4 hoses
Type 4 hoses shall be constructed as follows.
a) An inner lining of rubber resistant to LPG which shall be smooth, uniform and free from porosity and other defects which may adversely affect the performance or life of the hoses or hose assembly.
b) A reinforcement consisting of one or two layers of braided wire together with at least one helix of heavy wire embedded in the rubber. IC more than one layer of braided wire is used, each shall be separated by an insulating layer of rubber. The wire braiding shall be free from defects likely to puncture the lining or outer cover. Additional plies of either fabric or rubber may be applied immediately under or over the wire braid(s).
c) A uniform outer cover of synthetic rubber or synthetic rubber-i mpregna ted textile fabric which shall be resistant to ageing, abrasion, atmospheric exposure and to LIPG. Perforations in the outer cover are permitted in order to eliminate lifting” which can result from gas permeating the inner lining.
2.2.6 Type 5 hoses
Type 5 hoses shall be constructed as follows.
a) The hose lining shall consist of synthetic rubber suitable for continuous operation with LPG, shall be free from porosity and other defects which may adversely affect the performance or life of the hoses or hose assemblies and shall be supported on a round cross section internal wire helix.
b) The hose shall be reinforced with plies of textile in cord, woven or braided form or metallic cord together with at least one helix of heavy steel wire embedded in rubber. Reinforcement plies shall be thoroughly impregnated with synthetic rubber.
c) An open weave breaker fabric which shall be thoroughly impregnated with synthetic rubber and shall be incorporated in the outer cover of the hose.
d) A uniform outer cover of synthetic rubber or synthetic rubber-impregnated textile fabric shall be resistant to ageing, abrasion, atmospheric exposure and to LPG. Perforations in the outer cover are permitted in order to eliminate “lifting” which can result from gas permeating the inner lining.
e) Where joints are required to be made in the wire for either helix, they shall be electrically butt-welded prior to forming the helix. No weld shall be within 1.5 m of a nipple end in the hose or within 1.5 m of another weld in the same wire.
3.1 Operating conditions
3.1.1 Composite hose assemblies shall be suitable for a temperature range of— 50 °C to + 45 °C.
3.1.2 Composite hose assemblies shall have a burst pressure of not less than 100 bar at ambient temperature.
For composite hose assemblies required to comply with the IMO Code, which requires a factor of safety of 5: 1, the maximum working pressure shall be 20 bar; for other composite hose assemblies the maximum working pressure shall be 25 bar.
NOTE 1 The stated working pressure should not be exceeded under surge conditions.
NOTE 2 Means for the dissipation of static electricity are incorporated in the construction of composite hose assemblies.
3.2 Construction
3.2.1 General
Composite hoses shall be built on a mandrel and be of rough bore construction. The carcase shall consist of layers of polyamide or polyester film and fabric built on an inner helix of stainless steel wire and secured by an outer helix of stainless steel wire.
The condition of the helical winding shall take into account the resistance to twist on elongation whilst under pressure.
3.2.2 Basic construction
The basic construction shall be as follows using the materials specified in 3.3:
a) a helix of stainless steel wire evenly pitched and tightly wound on a mandrel;
b) plies of polyamide or polyester fabric spirally wound in position:
c) plies of polyamide or polyester sheet film spirally wound in position;
d) plies of polyamide or polyester fabric spirally wound in position:
e) an outer helix of stainless steel wire mid pitch to the inner coil and tensioned into position:
f) for composite hose assemblies of 102 mm nominal size and above, reinforcing members of heavy polyamide or polyester fabric built into the ends of the hose.
3.2.3 Protection against mechanical damage Where additional protection is required to avoid mechanical damage during manhandling of the hose it shall be provided by either:
a) an abrasion resistant protective coil of metallic or non-metallic construction designed to withstand the operating conditions envisaged; or
b) an additional outer cover resistant to wear, tear and abrasion.
4.1 Design requirements
4.1.1 Flexible metallic hose assemblies shall be suitable for a temperature range of— 50 °C to+45°C.
4.1.2 Flexible metallic hose assemblies shall comply with the requirements for flexibility type B or C and pressure class 4 or above of BS 6501-1.
For flexible metallic hose assemblies required to comply with the IMO Code, which requires a factor of safety of 5: 1, the design pressure shall be 20 bar; for other flexible metallic hose assemblies the design pressure shall be 25 bar.
4.2 Construction
4.2.1 Tube
Flexible metallic hoses shall be manufactured from seamless or longitudinally butt-welded tube in accordance with BS 6501-1, and of the material specified in 4.3.1.
After forming the corrugated hose, the surface shall be finished smoothly and shall be free from any defects which might cause failure of the hose in service.
4.2.2 Wire braid
Flexible metallic hoses shall be close covered by wire braid (see 4.3.2) machine woven around the tube.
4.2.3 End fittings
The assembly procedure shall comply with the
requirements for welded end fittings given in
BS 6501-1.
4.2.4 Protection against mechanical damage Where additional protection is required to avoid mechanical damage during manhandling of the hose it shall be provided by either:
a) an abrasion resistant protective coil of metallic or non-metallic construction designed to withstand the operating conditions envisaged; or,
b) an additional outer cover resistant to wear, tear and abrasion.
NOTE The nature of the hose construction makes it imperative that manufacture be carried out in clean conditions to avoid the inclusion of foreign bodies which may damage the wall of the hose.
4.2.5 Clean conditions Before, during and subsequent to manufacture, components and hose assemblies shall be kept free from any foreign bodies or deleterious substances.
4.3 Materials
4.3.1 The flexible metallic hose shall be constructed of austenitic stainless steel complying with BS 1449-2, steel grades 321S31 or 316S1 1.