Twin-arch moulded rubber expansion joint with female threaded union ends, for absorbing movement and pump vibration on small-bore pipework. Construction requirements for the type are given in ASTM F1123.
Prices on request. Contact us for availability and quotations.
This is a twin-sphere rubber expansion joint with threaded union ends. Two moulded arches in series give more movement than a single arch of the same face-to-face length, and the union nut at each end lets the joint be taken out without disturbing the pipework or springing the line apart.
The construction follows the pattern specified in ASTM F1123 for arch-type non-metallic expansion joints: an elastomeric tube reinforced with multiple plies of woven cloth or tyre cord, under a synthetic rubber cover. For a multiple-arch design ASTM F1123 requires the movement capability to be certified by the manufacturer rather than read off a table, so the axial, lateral and angular figures published for the size supplied are the ones that govern.
Union-ended joints are used on small-bore pump connections, booster sets, chiller and cooling-tower pipework and packaged plant, where a flanged joint will not fit and where the unit has to come out for service. The end pieces on the joint photographed are galvanised malleable iron with female threads and a hexagon union nut.
When ordering, state the nominal bore; the thread form - BSP taper to ISO 7-1, BSP parallel to ISO 228-1, or NPT to ASME B1.20.1, which are not interchangeable; the fluid and its temperature; the working pressure; and the movement required. Specify EPDM for water and glycol duties and nitrile for oil - EPDM is not compatible with mineral oil.
| Type | Arch-type non-metallic (rubber) expansion joint, multiple-arch, threaded union ends |
|---|---|
| Construction | Elastomeric inner tube reinforced with multiple plies of woven cloth or tyre cord, under a synthetic rubber cover |
| Reinforcement Material | Nylon, polyester, fibreglass or aramid; cotton is not permitted |
| Movement Capability | For a multiple-arch joint the movement capability must be certified by the manufacturer for the size supplied; it is not fixed by the standard |
| Pressure Rating Basis | Maximum allowable working pressure not more than one quarter of the measured burst pressure; production units hydrostatically tested at 1,5 x that pressure at the rated maximum operating temperature |
| End Connection | Female threaded union ends in galvanised malleable iron, with a hexagon union nut at each end |
| Thread Form | To be specified on order: BSP taper (ISO 7-1), BSP parallel (ISO 228-1) or NPT (ASME B1.20.1). These are not interchangeable |
| Elastomer Selection | EPDM for water, hot water and glycol; NBR (nitrile) for mineral oil and fuel. EPDM swells in mineral oil and must not be substituted for nitrile |
