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Date Posted: 05:50:50 11/26/06 Sun
Author: ¦óÚZµØ±ø»«©P+Åwªï¬µÊ\: jameslam@hkpro.com.hk
Subject: ²bÎx¦óÚZµØ±ø¤²µó©O+Åwªï¬µÊ\: nancychow@hkpro.com.hk
In reply to: ¦óÚZµØ±ø»«©P+Åwªï¬µÊ\: jameslam@hkpro.com.hk 's message, "²bÎx¦óÚZµØ±ø¤²µó©O+Åwªï¬µÊ\: nancychow@hkpro.com.hk" on 12:53:49 11/25/06 Sat

Notes:-

No less than 2 supports must be used on all pipes having lengths less than the minimum intervals indicated.

b) For UPVC pipes in vertical installation, only the anchor shall rigidly clamp the pipe, the remaining "C" clamp or split pipe rings spaced at intervals in above table shall only constrain the pipe in lateral direction but shall allow free movement along the axis of the pipe. These metal clamps or rigs shall be lined with UPVC sleeve.


UPVC pipes used for tank overflows, drains etc. shall be adequately supported such that no deflection of pipe occurs.

c) All supports for steel pipes including unplasticized PVC shall be ferrous.

d) All supports for copper pipes shall be brass. Where copper pipes are installed with other pipes and a single ferrous support is used, a PVC sleeve shall be provided at the point of contact.

e) Unless Otherwise specified, all hangers, support and brackets for steel or
iron pipes and unplasticized PVC pipes shall be stainless steel and for UPVC pipes all brackets shall be sheathed with plastic collar. All bolts, nuts and washers shall be strainless steel.

e) All pipe supports are to be of such design and type as to allow
for the removal of any pipe section without the necessity of disconnecting other adjacent pipes.

f) Where pipe rings are used they are to be split pattern with top
and bottom bolts. For horizontal pipes the rings shall be held by mild steel rod screwed to pipe ring boss and in all cases where rocking movement of the pipe ring is expected spherical seating washers shall be provided to all adjusting nuts .

g) In pump room area all pipe supports shall incorporate resilient rubber-in-shear pipe mountings to prevent vibration being transmitted to structure.

h) The discharge pipework form pumps and all pipework where vibration could be transmitted to the Building structure shall be supported with brackets etc. which shall have tough rubber washers at contact of bracket to pipe.

i) All supports etc. fixing to concrete structures shall be by using
of Philips red-head bolt fixing or approved equivalent for concrete and cutting away and building in of brackets in brickwork etc. The Sub-Contractor is to particularly not that it will not be possible to fix bolt fixing directly above the pipes to be supported, in such event, cantilever brackets shall be used where required.

j) External pipe brackets shall be primed with one coat of anti-
corrosive paint prior to installation.

7.11 Pipe Sleeves

a) Where pipes pass through walls, floors, ceiling, etc. the
plumbing Sub-Contractor shall provide and fixed the pipe


sleeves at the actua1 positions. Sleeves for cast iron and galvanized iron pipes shall be black steel; for copper pipes shall be either copper or brass. All sleeves are fitted through floors, they shall extend to at least 6mm clear of finished floor.

b) Sleeves shall be of slightly oversized to allow free movement of pipes.

c) The Sub-Contractor's attention is drawn to the vertical pipe
ducts. At all floor levels in the building, the ducts are to have floors and where pipes pass through these, sleeves are to be provided.


d) The gap between pipe and the sleeve is to be packed with
figreglass blanket material. However, for pipes/sleeves through fire barrier the gaps must be firmly sealed with soft packings having a period of fire resistance equal to the fire barriers. The ends of sleeves are to be caulked with non-hardening mastic to Surveyor's approval.

e) Details of pipes through walls and floors to be approved by the
Fire Services Department and the Surveyor before installation.

7.12 Pipe Anchors

a) All pipes shall be anchored as required to control the movement
of pipes due to thermal charges.

b) The anchors shall securely hold the pipe in a rigid position to resist the attempted movement due to expansion and the weight of the pipe and contents.

7.13 Cocks and Valves

a) General

i) All cocks and valves shall be of the type approved by the Water
Authority for their various purposes, capable of withstanding a hydraulic working pressure of not less than 12 BAR and Installed in accessible positions for ease of operation and maintenance.

ii) All valves shall be arranged so that clockwise rotation of the
spindle will close the valves.

ill) All valves exposed to view in lavatories shall be chromium
plated unless 'Otherwise specified.

iv) All valves installed in the flushing systems shall be of sea water
corrosion resistance type.

b) Draw off Taps

i) Draw off taps for potable water supply system shall be brass
and that for flushing water supply system shall be zinc free bronze or gunmetal.

ii) Unless otherwise specified, screwed down or spring type action
bib and pillar cocks shall be either brass or zinc free bronze, chromium plated with capstan head marked "Hot" or "Cold" and conforming to B.S.1010.

c)Stop Cocks and Valves

i)All stop cocks and valves not exceeding „w 50mm shall be bronze

with crutch head conforming to B.S.1010 for potable water

system.

ii) UPVC stop cocks shall be with wheel head conforming to JIS-

B2212 and shall be suitable for a working pressure of 9 BAR.

The stop cocks shall be entirely suitable for use with sea water.

Samples shall be submitted for approval.

iii)All stop valves for fresh/potable and flushing water supply

system exceeding „w50mm shall be flanged cast iron globe

valves with wheel head conforming to B.S.3961.

iv) Loose jumper type rough finish with easy clean cover brass stop

cock to B.S.1010, to be used where indicated bythe Water

Authority.

v) Drain cocks must be provided wherever required to ensure that

every section of pipework can be drainned.

vi) In particular cocks must be provided on the "dead" side of non-

return valves, and isolating valves on the mains.

d)Gate Valves

i) Gate valves up to and including 65mm bore shall be of

gunmetal construction fullway solid wedge pattern to B.S.5154.

All valves shall have inside screw gate, high tensile bronze

spindle and screwed bonnet. Valves shall have screwed female

ends.

ii)Gate valves of 80mm bore and over shall be flanged cast-iron,

fullway suice with inside screw solid wedge and high tensile

bronze spindle to B.S.5163. Valves shall have bolted bonnets.

iii) Valves fitted in valve pits shall have spindle with square head

and operating keys shall be provided, other valves to be cast

iron hand wheel to B.S.1218.


iv) All gate valves to be suitable for a test pressure of not less than 15 BAR.

v) Gate valves for flushing water system shall be fullway valves with external rising screw, flanged or screwed to suit the piping and shall be of cast iron construction with nickel alloy faces and Strainless steel spindle to B.S.3464. Valves shall be supplied by Glenfield and Kennedy or approved equal, full suitable and approved for use with sea water.

e) Ball Valves and Floats

i) Ball valves up to and including „w 65mm and using in potable
water supply system shall be brass conforming to B.S.1212 with copper float to B.S.1968.

ii) Ball valves up to and including „w 65mm and using in flushing water supply system shall be zinc free bronze conforming to B.S.1212 with plastic float to B.S.2456.

iii) Ball valves of„w80mm and above shall be of the Glenfield and Kennedy type fig. no. 1005* with cast iron valve body with
nickel alloy and stainless steel working parts . The valves for flush water shall have construction entirely suitable for use with sea water and floats shall be copper with neoprene coating. ( or equal and approved to relevant British Standard.

iv) Ball valves shall be of the slow closing type as specified above.

f) Check Valves

i) Check valves shall be bronze with square nut head conforming to B.S.5154 for potable water system and zinc free bronze for flushing water system.

ii) For check valve on the discharge side of potable and flushing water pumps, with the discharge outlet over „w 50mm, the check valve shall be either one of the following:-

1. "Vag" cast iron resilient diaphragm type check valves.
(Working pressure 16 bar. and W. Germany origin).

2. "GLEMFIELD" RECOIL CHECK VALVE - shall be
cast iron recoil single dish type figure nos. M7 s (working pressure 14 BAR) and 5101 (working pressure 16.33 BAR) and of U.K. origin.



g) Pressure Reducing Valves (for Fresh and Flushing Water)

i) Pressure reducing valves shall be of adjustable spring type
¡§Bailey's" T pressure regulator or approval equal, cast iron body, zinc free bronze trim fully suitable for salt water, slow closure and damped to ensure smooth operation without slamming.

ii) Valve to be protected by 60 mesh monel metal screen "Y" or "T" type strainer installed upstream. Strainer to be fully suitable for use on sea water. Reducing valve assembly to be installed in a readily accessible location close to the down-feed mains.

iii) One(l) 65 mm dial pressure gauge (scale 0- 3 5bar) to be installed at the upstream immediately-down-stream of the valve, with valve cock to read controlled pressure.

vi) All pressure reducing valves to be approved by Water Authority.

7.14 Welding and Brazing

a) Welders must have a current certificate of competency and in addition will be required to perform site tests of competency, should a welder fail such tests he shall replaced.

b) The Surveyors reserve the right to carry out welding tests on up to 2% of the welds on the installations. The Contractor shall include for remaking the joints where Cutout. Should the results of these tests indicate that the welds are not to the requirements of this specification the Contractor shall, if instructed, remove all pipe-work and welds performed by the welder and replace the work and pay all Costs incurred by other Contractors (if affected) without any additional charge.

c) All pipework for welding shall be supplied with plain ends,
joints being made with butt welds on the site. All welded joints shall be made by an approved welding process, each joint being of sufficient strength to with-stand the stresses imposed by internal pressure, from the expansion, weight of tube, and contents and the thermal insulation.

d) All welded tees, branches, vent pipes, reducers, etc. shall have bevelled, mitred joints, fused by a penetration weld and finished off with a fillet weld of ample dimensions. Care shall be taken to ensure that the welding metal or flux does not project into the bore of the pipe.


e) All welds shall be of good clean metal , free from slag
inclusions and porosity, of even thickness and regular contour, well fused with the parent metal and annealed and hammered on completion and finished smooth. all cuts from standard lengths of pipes shall be made by means of hack-saw, and burrs removed with reamer and the ends trimmed to a fair faced joint for welding. Each weld on black steel pipe shall on completion be painted with a coat of red oxide.

f) Copper pipes shall be either brazed or bronze welded to an
approved technique to B.S.1723 and B.S.1724. the welding rods to be of a type that is suitable for pipe material, contents and atmospheric conditions. All oxy-acetylene welding shall be in accordance to B.S.4872.

g) Welded pipe joints shall be permitted on pipes up to 150mm nominal bore only in situations where flanged joints are deemed by the Surveyor to be impossible or impractical.

h) Steel pipes having welded joints on the run shall be prepared for jointing in a manner suitable for the technique employed. Welding may, alternatively be carried out by oxyacetylene flame, or by electric metal-arc methods.

i) Oxyacetylene welding shall be by the Rightward technique as
described in Technical Memorandum T.5 issued by the British Welding Research Association and B.S.2640. Pipes shall be prepared for welding with ends sawn or cut off by hand, flame cut by machine of flame cut by hand with subsequent truing up by filling or by grinding to a level as may be required. Welding rods shall in all cases, be of good quality copper coated low carbon steel, and the manufacturer shall provide test certificates representative of the rods used in accordance with B.S.1453.

j) Welders identification works required to be stamped at each weld.

k) Metal arc welding shall be carried out in accordance with the techniques described in Technical Memorandum T.3. issued by
the British Welding Research Association and B.S.2633 : 1973 :
Class I or B.S.2971 : 1961 : Class 2, butt ends to piping being built up on either a base run deposited by the oxyacetylene process or a permanent mild steel backing ring. Electronics shall be of good quality in accordance with B.S.639 : 1976, be coated and be of such diameter that performance may easily be controlled to produce a weld of the required quality. All slag shall be removed after each run, undercut edges, slag pockets unsound metal and blowholes being chipped out as the work proceeds.




1) All welded joints, whether produced by oxyacetylene flame or
metal-arc processes shall be of first quality , the butts being slightly convex with regular ripples and no undercutting , washing away or surface cavities being present. Notches at the root indicating incomplete penetration and excessive weld protruding into the pipe bore in excess of 1.6mm inch shall not occur and the external reinforcement shall run out smoothly to the pipe surface on either side.

m ) Welding shall in all cases be carried out by skilled craftsmen
who are in possession of a current certificate of competency issued by an approved authority. The provisions of specimen welds, representative of the thickness and diameter of the joints and the conditions of site welding shall be submitted as required by the Surveyor in respect of every craftsman employed in such work.

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