Plastiline™ - Humes

UTILISATION
1 Principal applications
• Lining of spun pipes
• Lining vertically cast pipes
• Lining of cast insitu pipes
• Lining of maintenance holes
• Lining insitu structures such as
pumping stations and treatment plants
• Pile protection
• Precast concrete component protection
• Basement linings
• Tank linings for chemical
manufacturing plant
2 Degree of lining required
For minimum cost only those areas of the pipe surface which
are likely to be attacked need to be lined. The area needing
protection will vary with different service conditions. There are
basically two conditions:
H 2 S attack conditions only
The sequence of H 2 S attack - which finally produces acid
which corrodes the concrete - occurs only under particular
conditions of age, temperature, flow, sulfide content, etc.,
of the sewage. Only the concrete which is above the
minimum flow line will undergo attack, and hence lining
and protection is only needed above this flow line.
For medium and large sewer pipes the degree of partial lining
(see illustation) may only need to be 300 O or even less
leaving 60 O or more of the pipe invert exposed, which is not
at risk because it is covered by the flowing sewage. This is
particularly applicable to large trunk sewers.
There are situations where the lining must cover most
of the pipe surface. These are more common for
smaller diameter pipes DN 375 - 600 although
occasionally up to large sizes such as DN 2100. Such
linings are conventionally known as 359 O linings
(see illust.), although this does not mean that the full 359 O
will be covered.
0 = DEGREE
OF LINING
INVERT
GAP
Tolerance variations on pipe diameter and cutting the
Plastiline to size will mean that there can be a gap at the
invert varying from a few millimetres for small pipes, 50mm
for medium size pipes and 150mm for large pipes. Even a
few millimetres depth of sewage flow will cover any
exposed or unlined section.
Figure 1: Diagrammatic representation of the “H 2
S attack” mechanism.
SEWAGE
INORGANIC SULFIDES
ORGANIC COMPOUNDS
SULFATES
SULFUR
BACTERIA
AMMONIA CO 2
ETC. IN AIR.
SLIMES
BACTERIAL ACTIVITY FORMS
SULFIDES
INSOLUBLE - METALLIC SULFIDES
OXIDISED - MAINLY SULFUR
SOLUBLE IONISED
FRACTION
GAS EMISSION
TOTAL SULFIDES
SOLUBLE SULFIDE
DISSOLVED H 2 S
ATMOSPHERIC H 2 S
H 2 S
SILT
SLIMES
H 2 S AND O 2 ON PIPE WALL
BACTERIAL ACTION,
PROGRESSIVE PH REDUCTION
TO SULFURIC ACID
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