Elbows are bends with a very tight Radius, typically r=0.5x OD. Elbows allow changes in direction using minimal space. Injection moulded elbows have external reinforcement built into the design and are available in sizes up to dn630. In sizes above dn315 WSD require, segmented bends to be used in water supply. These are fabricated from pipe sections cut on a ≤ 7.5º angle and butt welded into one or more mitre joints ≤15º. Segmented bends cannot be manufactured with a tight radius, as space is required between each segment for the butt weld and to grip the pipe during fabrication. WSD required radus for segmented bends is r=2.5xOD (PS Appendix 22.09 Clause 5.5.4). Tighter radii segmented bends can be achieved using 15º cut angles however this means fabricating the bends using 3 x 30º mitre joints rather than 6 x 15º, however, 15º cut angle bends must be pressure de-rated as required in BS EN 12201-3 Annex B Table B3 making them unsuitable for the network as the bends rated pressure is less than the pipe.
Where there is insufficient space to install large radius segmented bends, fabricated elbows can be used. Similar to Fabricated tees, fabricated elbows are created by machining a fitting body from hollow bar. Reinforcement is included during machining and any angle from 1º to 45º can be created. Spigots are factory butt-welded to the fitting body to create a fabricated elbow with a radius of r=0.5xOD. No de-ration is required, as the reinforcement is included as part of the fitting design.
For angles greater than 45º, two fittings bodies that sum to the required angle (eg: 2x45º fabricated elbows = 90º) are factory butt welded together. Using this method any angle from 1º to 90º can be manufactured with a radius of r=~0.5xOD. These bends are ideal for installation in tight construction environments found in Hong Kong, or where there is insufficient space to install segmented bends in larger sizes. See some examples of Reinert Ritz fabricated compact short radius elbows in use below in both 90º and custom angles.
Fabricated Spigot Elbows / PN10-PN16 / SDR17-SDR11
Fabricated elbows come standard in 45º. Elbows up to 90º are manufactured by factory butt welding two 45º elbows together. Fabricated elbows are machined from black PE100+ compound in PN10/SDR17 and PN16/SDR11 ratings. They feature long spigots for electrofusion or butt fusion joining on site. Any fabricated elbow angle from 1º to 45º can be manufactured. Fabricated elbows have a radius of r=~0.5xOD.
For standard angles in Fabricated elbows, click on the links below for the dimension tables:
11º Fabricated Elbow
22º Fabricated Elbow
45º Fabricated Elbow
90º Fabricated Elbow