Wefatherm specification manual incl catalogue - page 19

19
Material properties
Material properties
Limitation mixed copper/PP-R
Hot water circulation systems
To avoid erosion corrosion in PP-R hot water circulation systems with
up-stream copper, respect following limitations:
Specific conditions, such as high concentration of chlorinated water
disinfectants combined with water having low pH or high ORP, will
affect the long term properties of PP-R.
For additional information contact your Wefatherm wholesaler or the
Wefatherm Export Sales Office.
3.5 Rubber gaskets
For connection and transition to other materials the Wefatherm system
incorporates items with gaskets.
Il
Illustration 3.10
The applied gasket material is EPDM Semperit E628 black.
This EPDM material complies with KTW approval 1.3.13 D1 and D2 for
cold and warm water:
- Hardness (Shore A): 70 ±5
- Density (g/cm
3
): 1,12
- Tensile strength (N/mm
2
): 11
- Elongation at break (%): 250
- Working temperature range up to 120°C
- Thickness 2,0 mm
- Resistance
For additional information on the chemical resistance of gaskets
contact the Wefatherm Export Sales Office.
3.6 Backing rings
Profiled flanges, PP encapsulated ductile
iron, have a specific design and are deve-
loped for the use in thermoplastic piping
systems.
Profiled PP flanges are being cast in duc-
tile iron GGG40 (ASTM A536), then
placed into an injection molding machine
and encapsulated with 30% reinforced
polypropylene. This process guarantees a
substantial corrosion protection barrier.
Illustration 3.11
This extraordinary pipe flange concept has proven itself successful widely
since 1979 in many countries in the world.
Advantages
- Extremely high corrosion resistance through the polypropylene layer
over metallic insert
- Convincing weight savings
- Substantially simplified handling
- 16 bar operating pressure
- Calculated, guaranteed safety factor of 2,0
- Elimination of re-torquing after initial installation
Re-tightening
Due to the reduced weight and the profile shape of the backing ring the
need to re-tighten the fasteners is eliminated. The unique flange shape,
acting like a 'Belleville washer', brings about the additional energy
storage needed to overcome any thermoplastic material cold flow condi-
tions. The design shape of the flanges is based on FEM calculations
(Finite Element Method) whereby special considerations have been given
to the thermoplastic stub end. For all flanges a safety factor of 2 is gua-
ranteed on the yield strength of the material for the stated maximum
operating pressures (MOP). For increased temperatures (>20°C)
it remains advisable to inspect the flange joint priodical and re-tighten
the fasteners if necessary.
Water temperature
max. 70°C
Operating pressure
according Appendix B1 and B2 of Spe-
cification Manual 2014 with max. 8 bar
Medium velocity
max. 0,9 m/sec
Against
Class
Ozone
well
Aging
well
Oils
not
Gazolines
not
Acids
well
Basen
well
Wear
suitable
Medium Dyn. (stat.)
Max.
Short term
Air
-40 (-50)°C +120°C
+140°C
Water
-
+120°C
+150°C
Conditions
Hardness
Strength
Yield
70 h/125°C +10 shore A +/-20% -40%
Time
Temperature
DVR
70 h
100°C
30%
Time
Pphm Ozone Temperature Crack phase
48 h
200 pphm 40°C
0
Table 3.13
Table 3.14 Temperature range
Table 3.16 Pressure deformation resistance DIN-ISO 815
Table 3.17 Ozone resistance
Table 3.15 Aging DIN 53608 temperature range
I...,9,10,11,12,13,14,15,16,17,18 20,21,22,23,24,25,26,27,28,29,...162
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