Standard dimensional ratio (SRD) represents numerical naming of a pipe series where a proper rounded number is approximately equal to the ratio of nominal outer diameter (dn) to nominal wall thickness (en). See the national standard INSO 14427-1.
See the relevant instruction in P.E.S website.
Due to flexibility, PE pipes are more resistant than other pipes to water hammer. PE pipes with SF=1.25 withstand up to 150% of nominal working pressure.
The pressure induced by water hammer at different velocities in different pipes:
DN 200 - PN10
PE 225* 20.5
DN 200 * 8
V= 0.5 m/s Speed
V= 1.0 m/s Speed
V= 1.5 m/s Speed
Cold PE pipes can be bent according to the formula R=a*OD where R is bend radius, OD outer diameter and a is bending ratio.
Bending ratio of pipe a
Weld edge has a negligible impact on water flow in the pipe. The welding edge is circular with a small height compared with inner diameter of the pipe.
This is taken into account in the Hazen-Williams of 155 for PE pipes. According to field tests, welding edge does not affect pressure drop or water velocity.
Since invention in 1957, three generations of raw materials have been provided for PE pipes.
Minimum Required Strength (MRS°)
MRS= Minimum Required strength
PE63 raw materials are no longer used, but pipes produced from PE63 are still working without damage around the world. In the mid-1980s, the second generation, PE80, was introduced to the market, Ten years later in the mid-1990s, the third generation, PE100, with improved specifications than the previous two generations was introduced to the market. A lifetime of 100 years has been predicted for PE100 pipes.