KRAH AG : STRUCTURED WALL PIPE TECHNOLOGY

WISA Appropriate Technology Conference,

Cape Town3 September 2007

Please visit www.krah.net

Who and What is Krah? Krah AG of Germany commenced 1969 40 polyolefin pipe plants worldwide Reference list over 260 major projects Structured wall - gravity pipelines (KPS) Structured wall - pressure pipes (KPPS) Diam 300-4000mm- 16kN/m2 or 2500kPa Comply with applicable standards Standard pipe designs - 129 profiles Customised designs can be computed APPROPRIATE for SA CONDITIONS

KPS STRUCTURED WALL

What are the Attributes?

Good hydraulics – smooth inner surface Tough – abrasion and impact resistance Chemical resistance – chemically inert Inspection friendly – bright yellow liner Safe joint – integrated electro-fusion Flexible – will flex not fracture Light weight – fast cheap construction Design is a permutation of 5 attributes 100 year life – environmentally correct APPROPRIATE for INFRASTRUCTURE

2700 mm DIAMETER

Are the Designs and Standards Adequate?

Hydraulic design ATV-DVWK-A110E a 79 page comprehensive document Sept. 2001

Structural design ATV-DVWK-A127E a 91 page comprehensive document Aug. 2000

Dimensions and Technical DIN 16961-1/2 System specification prEN 13476-1/2/3 Design software includes all in-situ soil

strength in the “soil pipe structure” Manufacture control software integrated

with design software to prevent errors. APPROPRIATE TECHNOLOGY for SA

PIPES and MANDRELS

Design is a Permutation of Five Attributes

pc

sd

pd

we

Equivalent solid wall pipe is, eq = (Ix . 12)^1/3

w=wall thicknesspd=profile widthsd=core tube diameterpc=core encapsulation e=neutral axis of wall

LARGE INTRICATE FITTING – note flange thickness

Is It a Complete System?

Bends, branches, laterals, reducers, house connections and in-line or tangential manholes

Design software “Easy Pipe” integrated with manufacturing software “Mickey”

Complete design detail submitted to client for adjudication and approval

Electro-fusion bar code in each socket Joint clamped; pressure + temperature Traceability of every weld and pipe

ALL SIZES LIGHT and EASY to HANDLE

RESULTS OF EASY PIPE DESIGNS

RUN 1: Standard Installation This is typical the in excess one that is done when data are not had on the

work, assuming conditions of standard installation. RUN 2: Very Low cover depths In this run the value of the minimum cover depths is modified, taking

minimun value accepted by EASY PIPE, that is 0.5 mts. RUN 3: Very deep cover depths In this run the value of the max. Cover depths, taking it to 7.00 is modified

mts RUN 4: Water table In this run the water table is added, to a height of 2 mts over the max. level

of the seat bed. RUN 5: Combination of all RUNS Here all the changes done in the previous runs are put into play, is to say

the parameters of RUN 1 but changing: the minimum cover depth to 0.5 mts, the Maxima cover depth to 7.00 mts and 2.00 the water table level to mts over the seat bed.

CORRIDAS EASY PIPE

0

5

10

15

20

25

30

35

0 500 1000 1500 2000 2500 3000

DIÁMETRO (mm)

RIG

IDE

Z A

NU

LA

R (

kN

/m2

)

CORRIDA 1 CORRIDA 2 CORRIDA 3 CORRIDA 4 CORRIDA 5

GRAPH OF RESULTS

CONCLUSIONSThe results show that, contrary to the intuition, the annular rigidity that need the tubes for certain condition of installation he is not constant, but that will depend on the diameter of such (to see graph). This must to the different interaction tube-settles (fundamental to obtain a joint package structural) that takes place in each measurement and thus it demonstrates that the rigidity of the tube only has an intervention limited in the structural resistance of the set.

Take note also how it substantially increases to the necessary rigidity before the combination of high cover depth and water table, which increases exponentially when the phreatic level rises.

Please visit www.krah.net