ENSIGN BURIED
DRAINAGE
TECHNICAL
55
D E S I G N R E C O M M E N D A T I O N S
Trench Preparation end of the drain, but not more than 4 metre
Ensign may be laid directly into a naturally head at the lower end. If necessary, pipe
trimmed trench allowing 50mm clearance at lines,may be tested in sections.
each joint between coupling and trench AIR TEST - Pipework should withstand a
bottom. The trench bottom should be flat to pressure of 100mm water gauge and this
give continuous support to the pipework. should not fall by more than 25mm in a 5
If the subsoil cannot be accurately minute period. However where traps or
trimmed with a spade. the trench should be gullies are connected they should withstand a
excavated to a depth of 100mm below the pressure of 50mm water gauge and this
pipe invert and a granular bed laid. This also should not fall by more than 12mm in a 5
should allow 50mm clearance at each joint minute period.
between the coupling and the granular bed. It is recommended that pipework
Where Ensign is to be set in concrete, the installations are tested in sections rather than
trench should be prepared as above to allow waiting to complete in one operation.
a minimum of 100mm of concrete under the
Q;@
pipe. Differential Movement
Ensign couplings allow up to 3° deflection
;;;;;;;;;
Fig. 13
Constructional at each joint.
Flexible Joint Pipelines leaving buildings, manholes or
;;;;;;;;;
Q;@Q;
other structures which are likely to be subject
➤
to settlement, should have a minimum of two
;;;;;;;;;
joints, a maximum of 600mm apart, thereby
allowing a short length of pipe to act as a
;;;;;;;;;
@
“rocker pipe”. The joint nearest the structure
should be as close to it as possible and, in
;;;;;;;;;
areas where large settlement is expected,
more than one “rocker pipe” may be required.
(See fig. 16).
56 The pipe should be supported on a Minimum Depth of Pipework
compressible material (e.g. expanded Ensign can be installed under most
polystyrene), either side of each joint. The buildings without further protection. Where
concrete should have a suitable flexible joint Ensign is installed under roads and yards
at intervals not greater than 5m in order to subject to normal usage, it is advisable for
reduce the natural rigidity of the concrete. additional protection to be considered if the
This should be made of a compressible cover is less than 1.2m. However, in areas
material (e.g. expanded polystyrene). which that are subject to special loadings or abuse,
should be placed next to a pipe joint, and extra protection should be considered.
conform to the full cross section of the
concrete. (See fig. 13). Falls
Haunching and surround should not be Pipework gradients should be chosen to
carried out until the pipework has been tested obtain a self-cleaning action under normal
and inspected. discharge conditions. For flows of less than 1
litre/sec. a gradient of 1 in 40 for 100mm
Testing pipe and 1 in 60 for 150mm pipe. are usually
WATER TEST - Gravity drains should be sufficient and for practical purposes, the
tested to an internal pressure of 1.5 metre gradients should not be less than 1 in 80 for
head above the invert of the pipe, at the high 100mm pipe and 1 in 150 for 150mm pipe.
Note: See BS EN 752-1 and relevant building regulations for further information.
D E S I G N R E C O M M E N D A T I O N S
Fig. 14
;; ;;;;;
;;;;;
ENSIGN BURIED
DRAINAGE
;;;; ;;;;
min. 600mm max.
➤ ➤➤ ➤
TECHNICAL
;;;; ;;;;;
;;;;
➤
;;;;;
➤
Flexible Joints
Access Fig. 16
Access is required on all pipelines to
facilitate the rodding and clearing of debris
and can be provided by manholes, chambers,
➤
access fitting or rodding eye - the latter
allowing downstream access only.
12
m
Generally, no part of a drain should be Rodding Eye
et
re
further from a manhole than 45 metres and
ms
ax
the distance between manholes should not
.
➤
exceed 90 metres. (See fig. 15) Gully
Fig. 15
➤ 45m ➤ 45m
➤ ➤
Fig. 17 57
MH MH
Where a drain connects with another drain
without the provision of an Inspection
Chamber or Manhole, access should be
provided on the branch drain within 12
metres of the junction. (See fig. 16 and fig. 17)
Below is a table of maximum spacing of drainage access points (in metres). For pipes up to and including
300mm dia.
Access-Fitting Inspection
From To small Large Junction Chamber Manhole
Start of external drain 12 12 - 22 45
Rodding eye 22 22 22 45 45 Reference the building
Access fitting regulation 1985 (2000)
Small 150Ø drainage and waste dis-
150 x 100 12 22 22 posal document H. H1 -
Large 225 x 100 22 45 45 sanitary pipework and
Inspection Chamber 22 45 22 45 45 drainage-table 10.
Manhole 22 45 45 45 90
D E S I G N R E C O M M E N D A T I O N S
It is recommended that access to the
Fig. 19
pipework is installed each time the drain
changes direction either horizontally or
vertically by the inclusion of an access fitting. Access
➤
(See fig. 18 and fig. 19).
Fig. 18
➤
Access Bend
➤
;;;
;;;;;
;;;
;;;;;
Access Branch
;;;;;;
;;;;;; ;;;;;
;;;;;;
;;;;;;;
Use of Bends/Branches
Bends in drains should be kept to a
;;;;;;;
minimum. Wherever possible bends should be
at or near to manholes or in a position which
allow ease of rodding (See fig. 20).
Inspection Chambers At the base of soil and rainwater stacks, it
Inspection chamber branch arm entries are is recommended that long radius bends be
all at 45° to conform with BS EN 12056/4. used (See fig. 19).
Where other angles of entry are Branches or junctions on drains should be
neccessary these can be achieved by the use - where possible - at access points, such as
of standard bends (See fig. 20). manholes, to facilitate rodding.
58
Fig. 20
➤
22° Long Radius Bend
30° Short Radius Bend
750mm
45° Medium 15° Short
Radius Bend Radius Bend
➤
➤ 1200mm ➤
D E S I G N R E C O M M E N D A T I O N S
Benefits of Rodding Point System ● Allows sectional testing to be carried out
during installation.
● Rodding blockages to an external manhole ● Removes the problem of running a branch
for removal is more hygienic. drain between two fixing points reducing the
● Quicker to install reducing installation costs. need for many small bends.
● Construction of manhole brick chambers no ● Fulfils the requirements of BS EN 12056/4
longer required. ● Designed to accommodate CCTV surveying
ENSIGN
Rodding Point with Floor Cover ➤
DRAINAGE
TECHNICAL
➤
➤
➤
Recess in
structural slab
Structural slab
Recess in manhole
➤
Bellmouth gully inlet ED060
100 x 45° Bend ED002 Cast iron 45° Branch ED006
Cast iron drain make up piece
➤
Cast iron main drain
➤
A Comparison of Systems 59
Traditional British Rodding Point
drainage System System
External ➤ External ➤
wall line wall line
T1 T1
T4 T16
T4
T5 T5 T2
T6
T2 T6 T3
T3 T8
T7 T7
T8
T9
T9
T10 T12
T12 T10
T11
T11
T13
T14 T13 T14
PUDDLE FL ANGES INSTALL ATION D E T A I L S
Where pipes pass through external walls,
in basement areas, a puddle flange may be ;;;;;;
;;;;;;
Fig. 23
;;;;;;
required. Location which may be below the
water table or in areas liable to flooding or in Bolt on
;;;;;;
areas which may need to be sealed against Puddle ➤
Flange
methane gas coming from made up ground ➤
➤
;;;;;;
etc. Denso ➤
The puddle flange reduces the risk of
;;;;;;
water entering the building by capillary action Pipe
when installed in a water retaining structure.
In figure 21 a typical build in detail is shown.
The two piece loose puddle flange is bolted
;;;
onto the pipe once it has been bedded on Figure 24 shows the build in type again,
denso tape or similar. this time one piece (4set screws) for use with
;;;
a 200mm pipe. The ED078 is a compression
Fig. 21 puddle flange which needs to be slipped over
;;;
the end of the pipe and put into position.
100/150
Then it can be tightened up with the rachet
;;;
wrench. The gasket within the unit is
➤
;;;
compressed on to the pipe, therefore no
;;;
denso tape is required.
;;; ;;;
Fig. 24
;;;
200
;;;
➤
Figure 22 shows a pipe passing through a
sleeve. This would be used where pipe work
;;;
60 is installed after walls have been constructed.
;;;
The areas between the pipe and sleeve is
;;;
sealed using a mastic type sealant.
;;;
Fig. 22
;;;
Figure 25 you can see that four bolts need
;;;;;
Mastic
Sleeve ➤ Sealant to be tightened up equally.
➤
;;;;;
Fig. 25
;;;
;;; ;;;;;
Clamp
;;;;;
➤ Ring
Puddle ➤
Flange
➤
;;;;;
Pipe
➤
Flange
;;;;;
In figure 23 we see how the puddle flange
is fixed and sealed onto the pipe. With
Ensign this type of puddle flange is available
as ED078 in 100mm, 150mm, 250mm and
300mm diameters.
