a look at some of the issues faced by clients and contractors at
WwTWs, and why higher levels of technical support from pipeline
suppliers are crucial.
by Simon Cottingham, Major Projects Director at Saint-Gobain PAM
diameter Pamlock mechanical anchor pipes laid on plinths
Extensions or upgrades to wastewater treatment works by
definition are located on the site of existing works. These
sites have often been built on, extended or renovated over many
decades. All of the challenges a contractor might encounter on a
multi-kilometre pipeline are condensed within the boundaries of
the works and typically over 50m-100m pipe runs. Contractors
find themselves dealing with a ‘perfect storm’ of existing
services and buildings, pipelines required above ground on
plinths or at extreme depth, contaminated and aggressive soil as
well as changes to design as work progresses and unforeseen
challenges present themselves. All of this means a far higher
level of day-to-day technical support is required from pipeline
suppliers than would normally be required. This support, if
sought at the early stages of design, can head off issues before
they become major problems.
Socket spigot systems
Pipe runs tend to be
relatively short and navigate around the services and existing
buildings typically found at wastewater treatment sites. Socket
spigot systems are ideal for these applications because they
offer the flexibility to cut on site to required lengths to
adjust the position of fittings and to accommodate design
Most designers specify
concrete blocks to provide thrust restraint for socket spigot
pipelines. As the pipe diameter increases so does the size and
cost of concrete thrust blocks, and this can become a deterrent
to specifying socket spigot systems.
Occasionally, flange pipe
and fittings are specified as a way of negating the need for
thrust blocks but the lack of flexibility of a flange joint in
buried applications will almost certainly result in premature
anchorage systems such as our Universal and PAMLOCK anchored
joints are flexible, simple and quick to install and are a
cost-effective alternative to concrete thrust blocks. Since they
do not require external bolts to lock the system together there
is no requirement for post-installation wrapping to protect the
integrity of the bolts.
On a recent project a
contractor installing a 1200mm diameter Universal anchorage
system took on average 15 minutes to complete the installation
of each joint, which is 75% faster than the typical installation
time of a traditional bolted anchor system.
Pamlock PUX coated pipes installed in aggressive soils
Pamlock PUX coated pipes laid between structures
There is a further common
misconception that anchorage is required at every joint. This is
rarely the case. Using Saint Gobain PAM’s Pipespec anchorage
calculation tool our technical team can consider all of the
parameters relevant to minimise the number of joints requiring
anchorage. In many cases water and wastewater is not being
transported at high pressures within the confines of a treatment
works and the mechanical anchorage required can be minimal. The
savings in design and construction costs can be significant as
well as negating the disruption to adjacent services and
buildings caused when trying to position a large concrete thrust
Often, treatment works
are built on brownfield sites with relatively aggressive ground
conditions. This can be a major issue for contractors and
clients requiring assurance of long-term system integrity. The
implications for not applying the appropriate level of corrosion
protection is unlikely to have an immediate impact on the
client, but can result in an expensive and highly disruptive
system failure at some point in the future.
Saint-Gobain PAM UK offer
soil surveys and ground investigation reports to enable
us to provide bespoke external pipe corrosion protection
systems for even the most aggressive ground conditions.
Corrosion protection can be localised to the soil
conditions at each pipe and any additional protection
limited to areas of need rather than across the entire
pipeline. Once again, early involvement of our technical
team allows decisions to be made on the most appropriate
level of corrosion protection to minimise cost whilst
providing assurance of long-term pipeline performance.
Universal Ve joint
Universal Ve joint
to DN 600
Allowable laid deflection
Pipe end displacement
Saint-Gobain PAM UK’s
Universal Anchorage System
The ANCHORED STANDARD Vi
joint is a push-in anchored joint for laying anchoring pipes.
The anchoring is designed to take up axial forces and allows
laying without the need for concrete blocks. It is suitable for
UNIVERSAL STANDARD double chamber socket pipes and smooth spigot
ends. Range: DN 80 to 600 (pipes).
Universal Vi joint
The basic principle of anchoring joints consists in transmitting
the axial forces from one pipeline component to the next, thus
ensuring that the joint does not come apart. The inserts in the
UNIVERSAL Vi anchoring gasket hook onto the pipe spigot, and
thus avoid having to install concrete anchoring blocks.
This anchoring system
also avoids the need for a weld bead on the spigot, and so can
be used with all smooth spigot ends and in double-chamber
The UNIVERSAL STANDARD Vi joint requires the use of UNIVERSAL
STANDARD pipes with double chamber socket. Leak tightness is
provided by a STANDARD joint gasket. The axial force
transmission takes place through an anchoring ring with inserts
embedded in the elastomer. They hook onto the spigot end when
the pipe is pressurized, thus ensuring joint anchoring. The
UNIVERSAL STANDARD Vi joint is not suitable for pipes in FGL
iron (grey iron).
UNIVERSAL pipes with DN 80 to 600 to be used with UNIVERSAL
fittings with similar DN (except DN 350 and 450, use fittings
with STANDARD joint and STANDARD Vi anchoring solution).
Anchored joints are of particular interest in congested
conditions that preclude the construction of concrete anchor
blocks, or in poorly cohesive soils.
The leak tightness of these joints relies on the proven
qualities of push-in joints.
The UNIVERSAL STANDARD Vi joint cannot be disassembled after
pressure has been applied.
The PAMLOCK (Pk) joint is
a STANDARD joint equipped with an anchoring system especially
designed for large diameters. The novelty of the system lies in
the use of shot particles, which hold the joint together without
recourse to bolts.
The anchorage takes up
the axial forces and allows concrete anchor blocks to be
The basic principle of joint anchoring consists of transferring
the axial forces from one pipeline component to the next, thus
rendering joint separation impossible. Anchored joints allow the
axial thrusts arising at particular points (bends, tapers, tees,
blank flanges) to be distributed over one or more pipes, thus
avoiding construction of concrete anchor blocks.
The seal is provided by a STANDARD joint gasket. The axial
forces are transmitted by a mechanical arrangement, independent
of the sealing function, comprising:
A weld bead, applied at
A locking ring,
consisting of several segments held together by elastomer
A device known as a
conformator, which transmits the axial force to the internal
socket surface by means of shot filling the annular gap formed
by the socket and conformator. The shot behaves like a fluid and
Distribution of the axial
force on the socket surface and conformator.
Automatic stretching of
the main on assembly.
Any subsequent movement
of the main during testing is consequently restricted to
residual shot settlement.
Pipes and fittings: DN 1400 to 1800. For DN 2000, please call.
The ANCHORED PAMLOCK joint is of particular interest where
congested conditions preclude the construction of anchor blocks,
or in poorly cohesive soils.
The ANCHORED PAMLOCK joint combines the advantages of flexible
joint pipes with welded joint pipes. The leak tightness of the
joint relies on the proven qualities of the push-in STANDARD
− 1° (pipe end
displacement 14 cm), DN 1400 to 1600.
− 0.5° (pipe end
displacement 7 cm), DN 1800.
PAMLOCK joint assembly is dealt with in a special leaflet. For
further information on PAMLOCK go to
operating pressure (PFA)
DN 1400 to DN 1600
Case Study: A major WwTW
in the north-west of England
Construction of a new process stream, capable at peak of
treating 5,500l/s of raw sewerage coming into the works.
Saint-Gobain PAM UK
products used: Pipework diameters from 200mm to 1800mm; range of
anchorage systems including Universal and PAMLOCK; a range of
external corrosion protection systems; standard coated pipes; TT
PUX and PECS coated pipes.
diameter Universal PUX twin main
coated pipe inserted into a concrete tunnel
Threading pipeline through lots of existing services and
structures; numerous changes in level and direction of the
pipelines; overcame need for concrete thrust blocks through
using Saint-Gobain PAM UK’s mechanical anchorage system; pipes
pulled through tunnels; some pipes to be positioned on plinths
and others laid in trenches.
Up to 4.5 bar test
Laid at depths of up to
Laid in aggressive soils
containing, among other things, high concentrations of ammonia.
Laid between existing
structures and roads, resulting in a high proportion of fittings
relative to pipe length.
was prepared by Simon Cottingham, Major Projects Director of
Saint-Gobain PAM UK. For further information on the range of
ductile iron pipes that are ideal for WwTW including the
Integral range, barrier coatings, Universal and PAMLOCK
boltless mechanical anchorage systems, valves, couplings,
adaptors, dismantling joints visit