The Specification, Bills of Quantities and Typical Details
For Water and Wastewater Networks
E.
2.5
2.7
Dielectric Nipples: Electroplated steel nipples with inert and noncorrosive thermoplastic lining,
with combination of plain, threaded, or grooved end types and 10 bars minimum working
pressure at 107 deg. C (225 deg. F) for water service mains and 16 bars at 107 deg C (225 deg.
F.) for Fire service mains.
SLEEVES
1
2.6
Specification for Water Networks
Volume 2/2
PVC pipe sleeves: ASTM D1785, Schedule 40
IDENTIFICATION DEVICES
1
Equipment Nameplates: metal permanently fastened to equipment with data engraved or stamped.
The information should be accessible and visible and should include manufacturer, product name,
model number, serial number, capacity, operating characteristics, labels of tested compliances and
essential data.
2
Snap-on plastic pipe markers: manufacturer’s standard preprinted semi-rigid snap-on type. Include
colour-coding to ASME A13.1 unless otherwise indicated.
BLADDER TYPE SURGE VESSEL
1
The surge vessel shall be manufactured as a welded carbon steel envelope containing a food quality
butyl rubber interchangeable bladder. The bladder shall be subject to a current certification issued
by NSF/ANSI 61 guaranteeing compatibility for use with potable water. The bladder shall be
designed to withstand the initial pre-charge pressure when the vessel is empty. The bladder shall
also withstand the maximum and minimum pressures that occur due to the water hammer.
2
The vessels shall be designed and constructed in accordance with the requirements of ASME VIII
Division 1. All activities (design, selection of materials, fabrication, inspection and testing) shall be
carried out in accordance with one code. Carrying out some activities in accordance with one code
and other activities in accordance with the alternative is not permitted.
3
Minimum corrosion allowances per surface shall be 3mm.
4
Vessel design shall be in accordance with ASME VIII Division 1, with permissible stresses
determined according to the quality of steel used.
5
The butyl rubber bladder shall be of heavy-duty type.
6
Each vessel shall be supported on steel saddles (horizontal) or skirt (vertical).
7
Horizontal arrangements shall run level. For horizontal configuration the vessel shall be fixed at the
lower saddle nearest to inlet, and shall incorporate a sliding bearing at the upper saddle, to allow the
vessel to expand and contract. The design of the saddle supports shall comply with the requirements
of BS 5276-2 with respect to materials, dimensions and tolerances.
8
All pipe connections to the surge vessel shall be flanged. Where electrical isolation is required
flanged connections shall be fitted with flange joint insulation kits. Where insulation kits are to be
fitted flange bolt holes shall be drilled 2mm larger than specified on the appropriate flange standard.
Details of the flange drilling shall be stated on the vessel drawing as necessary.
9
Each surge vessel shall include the following:
A. All nozzle flanges for air charging valve and drain valve
B.
Drain valve (at the lowest point of the vessel)
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The Specification, Bills of Quantities and Typical Details
For Water and Wastewater Networks
C.
Specification for Water Networks
Volume 2/2
Air charging valve
D. Manhole for inspection purposes sized in accordance with the requirement of BS 470 with davit
arm/hinges
E.
Direct reading pressure gauge
F.
Tank supports
G. Access platform ladders and platforms (if applicable)
10 Each surge vessel shall also include DN 100 or DN 150 bridles for the security level gauge system.
This will include the following:
A. Direct reading level gauge (differential pressure type)
B.
Level transmitter
C.
Level switch (high level alarm)
D. Level switch (low level alarm)
E.
Stainless steel solenoid valves and non-return valves
11 A security level gauge system shall be installed on each vessel. This system shall be made up on a
non-magnetic steel tube connected via isolating valves to the top and bottom of the surge vessel. A
magnetic float in the tube registers the water level in the vessel and the float position is detected by
external magnets that activate micro-switches connected to any control loop which may be located
at any level on the tube. A special assembly of non-return valves and solenoid valves are to be
included and shall be designed to close if high rate water discharge is detected in the tube. This
aspect of the system allows the level tube to operate continuously even in transient conditions with
no risk of loss of gas through the tube by venture suction effect. Two additional micro-switches are
to be located on the level tube to detect high and low water levels in the surge vessel and a
corresponding signal sent to the respective junction box.
12 The main flanges outlet of the vessel shall be equipped with an anti-extrusion grid to reduce
turbulence and to avoid expulsion of the bladder during the initial pre-charge. The head losses
through the grid must be as little as possible.
13 A cross-piece shall be fitted to the top of the vessel to facilitate the following:
A. Gas filling of the vessel
B.
Fitting of stainless steel pressure gauge
14 Surge vessels shall be constructed from steel plates in compliance with ASTM A516 Gr 70 and shall
be normalized. The pipes shall be to API 5L Gr B or ASTM A106 Gr B. Seamless fittings shall be
to ASTM A234 Gr WPB and flanges shall be to NF EN 1759 - 1. The complete vessel shall be stress
relieved. No welding shall be permitted after stress relieving of the vessel.
15 The surge vessels shall be internally and externally coated.
16 The surge vessels shall receive a heavy duty/high performance external coating system with a
minimum thickness of 325 microns as follows:
A. Primer Coat:
Zinc Rich Epoxy (75 microns)
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The Specification, Bills of Quantities and Typical Details
For Water and Wastewater Networks
B.
Undercoat:
C.
Intermediate Coat:
Specification for Water Networks
Volume 2/2
High Build Epoxy (100 microns)
High Build Epoxy (100 microns)
D. Finish:
Polyurethane acrylic (50 microns)
17 The surge vessels shall be coated internally using food quality powder coated epoxy system to a total
dry film thickness of 650 microns minimum. The paint must be certified compatible for use with
potable water by recognized international authority.
18 The manufacturer shall submit the details of the paint and application system proposed for the surge
vessels. The manufacturer shall submit the thicknesses of all coating/painting layers.
19 The finish color for the surge vessels shall be Medium-Grey (BS 4800 00 A 05).
20 All painting and coatings shall be holiday tested.
21 Coating thickness shall be tested.
22 The vessels shall be inspected and tested in accordance with the general requirements for Inspection
and Testing as defined in Paragraph UG-90 of ASME VIII Division 1. All inspection and testing
shall be performed in accordance with the detailed QA plans for the vessel and shall be approved by
the Engineer.
23 The Vendor shall produce material test certificates for all components making up the surge vessels
in accordance with ISO EN 102043.1 Certificate.
24 If any defect is detected during the tests before completion or during the warranty period, the faulty
equipment shall then be rectified immediately by the Vendor at his expense. If the fault cannot be
rectified, the Vendor shall then replace the defective equipment which shall also be proven to be free
from defect.
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