Pressure and angular deviation at the joint

With the term “pressure”, a distinction needs to be drawn between terminology used by:

  • the network designer (dependent on the hydraulic capacity,
  • the manufacturer (dependent on the product performance),
  • the network user (dependent on the service).

Terminology
The terminology listed below is drawn from the draft European standard EN 805 – Water supply. Specification for external networks and components – applicable to all materials.

The product standard EN 545 - Ductile cast iron pipes and fittings - uses this terminology where the manufacturer is concerned.

Manufacturer’s definitions

Terminology
 

Abbreviation

French

English

German
Designer dp Pression de calcul en régime permanent Design pressure Systembetriebsdruck
Mdp Pression maximale de calcul Maximum design pressure höchster Systembetriebsdruck
Stp Pression d’épreuve du réseau System test pressure Systemprüfdruck
Manufacturer PFA Pression de fonctionnement admissible Allowable operating pressure zulässiger Bauteilbetriebsdruck
PMA Pression maximale admissible Allowable maximum operating pressure höchster zulässiger Bauteilbetriebsdruck
PEA Pression d’épreuve admissible Allowable test pressure zulässiger Bauteilprüfdruck
User op Pression
de fonctionnement		 Operating pressure Betriebsdruck
Sp Pression de service Service pressure Versorgungsdruck

PN - Nominal pressure (in compliance with Standard EN 545)

Numerical designation expressed by a number used for reference purposes. All flanged components with the same DN and designated by the same PN are compatible for interconnection.
Standard EN 545 sets out for flanged pipes and fittings, the following PN equivalents in PFA, PMA and PEA.

DN

PN10

PN16

PN25

PN40
 

PFA

PMA

PEA

PFA

PMA

PEA

PFA

PMA

PEA

PFA

PMA

PEA
40 to 50 See PN 40 See PN 40 See PN 40 40 48 53
60 to 80 See PN 16 16 20 25 See PN 40 40 48 53
100 to 150 See PN 16 16 20 25 25 30 35 40 48 53
200 to 300 10 12 17 16 20 25 25 30 35 40 48 53
350 to 1200 10 12 17 16 20 25 25 30 35 - - -
1400 to 200 10 12 17 16 20 25 - - - - - -
For DN 80 flanged parts manufactured by PAM, use the following equivalents:
80 See PN 40 See PN 40 See PN 40 40 48 53

Leaktightness test pressure (in the sense of Standard EN 545)


Pressure applied to a component during its manufacture to ensure its leaktightness.

Pressure and angular deviation at the joint
Water hammer
If protection devices have not been provided, ductile iron pipes have a safety coefficient which is often useful when faced with accidental pressure surges.
Joint deflection
Joint deflection
The angular deflection allows negotiation of large radius bends.