Piping the New World

Joined Methods for PE Pipes

Pressure decreasing coefficients related to heat

The PE pipe systems design has been made for 20 C. The maximum working heat is 40 C. But if there will be ongoing flow with degrees over 20 C, the pipe should be chosen related to the below coefficients.

Heat (C)
Coefficient (F)
20
1
30
0,87
40
0,874


Interpolation can be made for the in between heat intervals
The allowable working pressure PFA, is calculated from the equation below.

PFA = fl  x fA  x PN
fA : Increase or decrease factor fA = 1 according to usage { in water fast}
PN : Nominal pressure

Compression fittings
For small bore pipe connections up to size 125MM OD. Compression typw  joints are satisfactory. The installation process started with the cutting of pipe ends square or 90 in relation to its axis. Fit the collar and clinching ring into the push the boddy of the filling until the pipe ends reaches its full stop. Slide the clinching ring and collar (Nut ) until it actches the filling and tight fully using a belt or chain wrench.

Flange Adaptor
This is another type of conventional mechanical jointing. A PE Flange Adaptor ( Stupend) is butt welded to the pipe with the loose steel backing flange inserted inside. A standard number of bolts will be fitted to tighten the connection. This type of connection is practical for application which requires easy serviceability in the future.

Butt Fusion welding
The process Starts by Cutting The pipe ends straight and square to the axis and cleaned carefully by  an electric planer. The pipes and fittings are held tight and pressed against a coated heating plate. As soon as the heating time and the required bead are reached the heating time and the required bead are reached the heating plate is quickly withdrawn from the weld face and the connection are pressed together to form a permanent joint.

Proceduce for Butt Welding
Polyethlene pipes may be produced to be connected by butt welding method depending on the project. But there are limitations for connection with this welding method in respect to both diameter and wall thickness. Connection with this welding method can be applied to diameters between 50mm and1600mm : and relative to the diameters, to wall thickness from 5mm to 100mm. butt welding process is carried in accordance with DVS 2207 standard.

Matters to Be paid attention in connection of PE pipes with butt welding methods:

  • ◊  Heat of the welding environment should not be below 5 C .
  • ◊  Wall thickness of the pipes to be connected must be equal, if there is any difference, then the difference must not exceed 10%.
  • ◊  Butt welding machine to be used in welding must be certified.
  • ◊  Prior to welding process, welding surfaces must be scrapped, oxidation removed and complete contact of welding surfaces must be provided.
  • ◊  After scrapping of the welding surfaces. It must be preserved from dirt. If there is any re-dirtying, the scrapping process must be repeated.
  • ◊  Prior to being heated with iron, the surface to be welded must be cleance with pure alcohol.
  • ◊  Although the weld iron heat is between 200C – 220C, it must be designated regarding the raw material of the pipe and application standard.
  • ◊  After the weld process has started, during weld cooling period the connection pressure values of the pipes must be kept equal.
  • ◊  Since, the air circulation formed in the pipes accelerates the cooling process of weld, during welding one end of the pipes nust be closed.
  • ◊  Before starting welding process the heat values of the machine must be checked and welding must be started 5 mintes after reaching desired heat value.
  • ◊  Iron part of the machine and the welding part of the pipe must be cleaned prior to welding.
  • ◊  Welding pressure test for pressurized drinking water pipes are applied in accordance with EN 805 standard.
   

Pipes Installation Procedures

- Procedures for pipe installation are states in DIN 1963. DIN 18300 and EN 1610 standards pipes may be lowered to the canel after being welded outside the canal. Keeping canal excavation narrow is the important matter in here.

- Pipes must not be crushed in no matter.

- Usage of pipes damaged during stocking or transportation (damaged by sharp tools or maternal like stone) must be strictly avoided.

- The must not be any accumulation of subterranean water or rain water in the canal (in case of presence of water in canal, it must be discharged by pumps)
Non-sticking sand, pebble, mixed sand with mixed grain and pebble are suitable for use as filling material (DIN 19630 standard)

- Canal depth must be of minimum 70-80-cm

- If the excavation soil is suitable for filling. Pipe may be laid on bottom of canal without need for bedding. If the excavation soil is not suitable ( stony, moist,etc) for filling, canal depth must be increased and bedding with dry filling material (e.g. sand) must be applied.

Transport And Storage Procedures

  • ◊  Thickness of bedding to be done must be minimum A1 = 100 mm + 1/10 DN. Bedding material must be compressed with a lightly working compactor until a95% endurance is obtained.
  • ◊  Pipe side fillinf A2, must be poured at 30 cm width and must be compressed with a compactor at a rate of 92-95%. This process must be continued in every 30 cm until exceed pipe for 30 cm.
  • After pipe is passed for A3 = cm, filling process must be completed by compressing with a mid power compactor.