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Date Posted: 12:53:49 11/25/06 Sat
Author: ¦óÚZµØ±ø»«©P+Åwªï¬µÊ\: jameslam@hkpro.com.hk
Subject: ²bÎx¦óÚZµØ±ø¤²µó©O+Åwªï¬µÊ\: nancychow@hkpro.com.hk

n) When the general hydraulic tests of the completed systems are
carried out, as detailed elsewhere each weld shall be lightly hammered during the time that pressure is maintained. If any leaks occur at welds the portion of the weld near the leak shall be cut out and re-welded. Such leaks shall not be repaired by caulking or attempted fusion of the surround metal. Should a considerable portion of ¤] e welded joints be made by a particular operator be found to be defective due to faulty workmanship, all such welds shall be cut out and re-welded by another operator whose work has proved satisfactory.

7.15 Jointing of Concrete Pipes

a) For spigot and socket pipes, the spigot shall be placed in the
socket of the pipe previously laid, and the pipe then adjusted and fixed in its :final position to correct lines and levels and accurately centered. A ring of tarred rope-yarn shall be next inserted in the socket of the pipe previously laid and driven home with a wooden caulking tool and mallet; when in position such yarn shall not occupy more than one quarter of the depth of the socket. The socket shall then be filled with a cement-mortar fillet worked all round. The fillet shall be bevelled off and shall extend for a length of not less than 50mm from the face of the socket.

b) For "Ogee" pipes, the joints shall be thoroughly cleaned and
wetted, and cement-mortar shall be applied evenly to the ends so as to completely fill the joint. The pipes shall then be properly drawn together and the outside of the joint shall be neatly pointed.

c) Special care shall be taken to remove any excess mortar and to
clean each pipe by drawing a tight-fitting was through as the work proceeds. The trenches and pipes shall be kept free from water until the joints are thoroughly set after which time the pipes shall be flushed from end to end with water, and left clean and free from obstruction.

d) For pipes with flexible joints , the pipe manufacturer's instructions shall be closely followed. The joint shall be carried through to the foundation so that the overall flexibility of the pipe line is maintained.

e) For pipes with precast concrete collar-joints , one half the length
of the collar shall be caulked onto the pipe using a suitable collar support to hold the collar concentric with the pipe. 1:3



cement mortar shall be used in caulking on the collar in layers not exceeding 40mm in thickness with suitable tools. After the caulking is completed the joints shall be covered and kept moist for three days. The tongue-end of the pipe shall be slipped into the collar during the laying process and the annular ring poured or caulked with 1:3 cement-mortar, taking care to make a smooth internal connection. This method of jointing shall be used on plain buttended pipes or on tongue-and-groove pipes.

f) For pipes butt ended with in-situ collars, cement-mortar shall be
applied evenly to the ends of the pipes to be jointed. The pipes shall then be properly drawn together. Excess mortar shall be removed to make a smooth external and internal connection.

g) Precast or in-situ collars shall be constructed as shown on the Drawings.

7.16 Jointing Pipes of Different Materials

a) Ductile Iron to UPVC Joints

Where UPVC branch pipes connect into ductile iron droppers on the flushing installation, special cast iron fittings shall be used. These fittings shall have flanged connections for coupling to the main and modified union connection on the branch with fibre-gasket for connection to UPVC branches

b) Copper to Ductile Iron or Steel Joints

Where copper flanges join to C.I. or steel fittings, valves etc. of ferrous metal, special sleeves shall be inserted in over-drilled bolt holes to isolate direct contact to bolts and flanges. Similarly , high strength flat fibre washers to be used on both ends of the bolt between the steel washers and flanges to prevent direct dissimilar metal contact.

c) Galvanized Steel to Cast Iron Drainage Pipe

Galvanized to cast iron joints are to be made with hemp and caulked lead , cold caulking compound "Philplug" PC3 or PC4, or an approved
jointing compound well rammed into the socket.

d) UPVC to Cast Iron Drainage Pipe



UPVC to cast iron sockets or bossed connections shall be made with screwed joints or caulked cement and yarn, cold caulking compound or approved jointing compound.

7.17 Expansion Joints

a) Wherever possible, advantage shall be taken of changes in direction of pipes to take up expansion and contraction due to temperature changes of the pipe contents .

b) Expansion joints and movement joints shall be provided on
pipes across the building expansion joints and elsewhere to absorb the effect of expansion on pipes as generally shown on the Drawings. Special attention shall be paid to provision of expansion joints on hot water pipework.

c) Where expansion joints are required, they shall be bellows type. Bellows shall be stainless steel with stele inner and outer telescopic sleeves. The joints shall have screwed ends and flanged joints for Joints of larger bore. The joints shall be suitable for a test pressure as specified for the pipes. Each joint shall be suitable for a traverse of not less than 25mm and if necessary a joint of larger diameter than the pipe shall be installed with reducing fittings to obtain the allowable required pipe movement.

d) Where movement points occur, couplings as Messrs. Viking Johnson or equivalent equal and approved shall be used so that building movement does not cause fracture of the pipework, etc.

e) Upon sizing and fixing expansion joints on pipes across the building expansion joints , the Sub-Contractor shall take into account, in addition to the expansion/contraction of pipes due to the temperature changes, the effect of the relative horizontal movement between the two parts of the building structure separated by the building expansion joint.

f) Expansion coupling with neoprene seal ring at one end to be used on UPVC piping.

g) On UPVC vertical/horizontal drainage pipe, axial expansion
coupling, as recommended by UPVC pipe/fitting manufacturer, to be supplied and installed as shown on the Drawings, of slip type with neoprene seal ring between the two coupling members. Class and standard of expansion joint to be the same those for pipes specified.



h) Where steel, cast iron, or UPVC drainage pipes cross building expansion Joints , expansion joints, mainly for lateral movement
(as well as for axial), of either stainless steel bellows of neoprene convolute design to be used.

i) Generally expansion bellows shall be installed mid way on each
water riser. Details and location of expansion joints shall be submitted to the Surveyor for approval.



7.18 Pipe Guides


Pipe guides, are for use in long lengths of pipe and tube and are to be fitted on each side of every joint to keep and to direct the movement of expansion and contraction from anchor points in true alignment in lateral direction towards the bellows or other flexible inserts shall take the form of enclosing hoops of mild steel flat to B.S.3974 : Part I, generally 40mm x 20mm in section. Such shall be secured to roller brackets and other fixings by means of bracket attachments. Metal guides for UPVC pipes shall be lined internally with UPVC material slightly oversized to allow axial movement of the pipe.


Generally, guides shall be fixed at points between the anchors and expansion joints to ensure that the thrust is linear to the axis of the pipe.


7.19 Flexible Connection


a) On suction of all flush and fresh water pumps.


All stainless steel construction, double flanged, flexible hose, one for each pump, full line size, rate 7 BAR, working pressure, fully suitable for sea water when used on flush water pumps. Minimum length between flanges to be 300mm.


b) On discharge of all pumps.


All stainless steel construction, externally braided, double flanged, flexible hoses, two for each pump, full line size, rate 17 BAR minimum working pressure, fully suitable for sea water when used on flush water pumps. Minimum length between flanges - 300mm.


7.20 Strainer


Strainer shall be Y pattern bronze body for potable water system and gunmetal body for flush water system with screwed connection up to „w 65mm and cast iron body flanged for „w 80mm and over, with removable mesh s.s. baskets and of such design as to permit blowing out of accumulated dirt without discontinuity of service. Strainer shall be provided as specified and shown on the Drawing.

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