الحمد لله والصلاة والسلام على رسول الله وعلى آله وصحبه أجمعين choosing HVAC PIPE WORKS AND FITTINGS Selection Tips DETAILED TECHNICAL SPECIFICATION General a) They must be installed with a view to an easy and even flow of fluid to and from all apparatuses without air pockets It should be installed for quick, sure and positive drainage and provisions for quick and noiseless air escapement b) All parts of the system must be capable of being vented air vents must be provided at the highest points of all risers vents must be piped at their points of connection to the piping system and to a visible drain c) Piping must be run, in general, forming right angles with or parallel with walls and neatly spaced, must be installed so that there is clearance of at least 25 cm, between finished coverings and the adjoining d) Piping must be hung in ceiling void as close as possible to bottom of slabs, beams, etc., maintaining required and co-ordinated head room at all times e) Dielectric connections must be provided for joining two different pipe work materials or pipes and equipment in order to isolate cathodically the pipeline or the equipment These connections must be rated to withstand the maximum medium temperature and pressure f) All necessary line valves for the satisfactory isolation of components and sections of the system are to be supplied and fitted g) Bends should be used in performance to elbows wherever possible h) Equipment and apparatus must be installed as to be totally readily accessible for operation and maintenance i) Wherever pipe work passes through walls and floors, mild steel pipe sleeves must be provided sufficient to ensure free movements In addition, chromium plated floor plates are to be fitted in the office blocks or where directed by the Engineer j) Pipes connected to vibrating machinery must be isolated from the supporting structure by vibration eliminators designed for supports by hanger rods. Pipes must be isolated from the vibrating machinery by use flexible metal pipeline connectors of metal to suit the fluids conveyed and the surrounding conditions In all lines carrying liquids drain valves must be installed at all low points in the system at the end of every primary or secondary main at intervals and not more than 75 meters in all horizontal pipe lines and all equipment positions. The drain connections must be provided with a drain line leading down with drain cock to the nearest drain pit The size of the drain lines and drain cocks must be 1- For pipelines below 4" dia. the drain line and drain cock must be 1" 2- For pipelines 4" dia. and above the drain pipe and drain cock must be 1.5" 3- For outside drainage points on 4" & above pipe works drains must be 2" 4- Dirt pockets must be installed on all pipelines the dirt pockets must be located in the pipelines at 1- All low points in the system 2- Ahead of any rise in the piping 3- At every 120m (max) of level piping with a relative constant demand during design operation 4- At the end of any primary or secondary main 5- Every 60 M (max.) of level, piping with considerable on-off demand during design operation 6- Ahead of all pressure reducing and control valves unless the branch feeding the valve is taken off the top the main and is less than 1.5 m in length All piping, fittings and flanges must be cleaned and thoroughly degrease before assembly. The entire system must present a neat appearance for both workmanship and grouping Welding Welding must be done by gas or electric arc process using equipment and plant laid down by BS 1821 and BS 2633 The method of welding and testing must be in accordance with the practice recommended by the BSI and AWS All operatives must be thoroughly experienced and have certificate of competency. If necessary, these certificates must be produced for scrutiny by the Engineer and welders must be required to take such test as required by A.P.I. Standard 1104 or as required by the Engineer. Lloyd's Surveyor or equivalent. If necessary if there is bad workmanship in the opinion of the Engineer, must be instructed to: a. Forthwith remove the operative responsible from the site b. Replace all welding works carried out by the Operatives. When welding is carried out, or a blowlamp used, adequate protection must be given to prevent damage to any part of the building The outside diameter and the wall thickness of butt-weld fittings and welding neck flanges must be the same as the outside diameter and wall thickness of the pipes to which they must be welded Heat generated by welding must not be allowed to accumulate at any bearing bearing retainer, machined surface, or dis-similar metal components Precautions must be taken to dissipate the heat as it is generated The joints must be tested to maximum tension required at the ambient temperature and pressure. The joints must also be subject to a compression test up to a maximum deflection shown on the Data sheet, at service pressure and ambient temperature. At the completion of those tests, which are to be repeated in accordance with the required number of cycles, the joints are to be re-subject to a hydrostatic pressure of 1.5 times the working pressure After completion of the above tests, the expansion joints must be rejected if there are any leaks or sign of breakage of any point or part of the bellows 15% of all welds must be X-rayed. This identification number of the joints must be stamped or painted on a metal sheet and fixed to the expansion joint by wire Both wire and metal sheets are to be corrosion proof Jointing Up to and including 50 mm bare pipe may be either welded or screwed for all cold services and hot services up to a working temperature of 85 Deg. C The pipe must be welded with flanged joints, above the size and where buried under ground welding must be permitted with flanged joints The use of flanges must be limited to the flanged connections to the valves and equipment and the following - Location of different access, and high and low points - Inspection holes - On straight runs of pipe where frequent dis-assembly operations for cleaning and maintenance may be necessary. The interval between flanges should not normally exceed 15 m - Positions where equipment dis-assembly requires pipe removal All bolts must be of stainless steel as per BS requirements Supports and Hangers All pipe supports and hangers required for installation of the pipes must be provided by the contractor. Vertical risers to be provided with suitable iron clamps. Brackets under the supports of pipes must be provided with sheet metal cradles to spread the load. Pipe supports pattern to be approved by the Engineer and must be Roller type Protective covering shield must be provided between all pipe supports hangers and the insulated piping. Shield must be made of a stout gauge galvanized mild steel of sufficient length to prevent depression of pipe covering Additional supports must be provided and installed within 300 mm where pipes change direction and adjacent to flanged valves strainers, equipment connections and heavy fittings All vertical pipe run must be supported and laterally braced at least once, at each building level Unless otherwise indicated on the drawings, vertical pipes must be supported with riser clamps, installed below hubs, couplings or lugs welded to the pipe Hanger and supports must be prepared and painted Insulated copper pipe must be supported by copper supports or copper plated hangers Pipe Sleeves All pipes passing through walls, partitions and ceiling must be provided with pipe sleeves. Sleeve size must allow for the free movement of pipes Sleeves passing through the finished service or exposed to view must be flush with the surface of the partition through which they pass and must be provided with suitable end covers of approved pattern and finish Expansion and Contraction of Pipes must be dealt with by compensators. In all locations where expansion is not taken by piping offsets, they must have stainless steel or chromium melypelenum bellows and/or loop. Expansion more than 3/4", expansion bellows/loop must be used. They must have 3 rigid plot straps type guides with adequate bearing surface fixed at 4 times as the diameters on each end and suitable to prevent any axial movement Anchors must be provided between expansion units These must be of sufficient strength to hold the mains tight against movement and withstand the thrust due to pressure and expansion but must not crush or injure pipe walls. consult the manufacturer for the precise position of the compensator and anchors and the amount of expansion that is to be taken by the compensators. make the calculations of expansion bellows, guides and anchors and obtain approval of the Engineer prior to commencement of the works Flanges must be provided on both sides of each piece of equipment in the plant and where required, having diameter 2.5" and above must be according to BS 10 or BS 4504 or equal approved Unions must be provided on both sides of each piece of equipment in the plant having diameter less than 2.5" Dielectric Joints must be provided for jointing two different pipe work materials or pipe work and equipment in order to isolate cathodically the pipeline or equipment This connections must be rated to withstand the maximum, medium temperature and pressure Vibration Eliminators Pipes connected to vibrating machinery must be isolated from the supporting structure by vibration eliminators design for support by hanger rods Pipes must be isolated from the vibrating machinery by use of flexible metal pipeline connectors of metal or rubber flexible joint, to suit the fluids conveyed and the surrounding conditions Valves All valves must be factory fabricated and of types as shown on the drawings Valves must be marked with name of manufacturer, trademark, nominal size and the class number, all casts in the valve body Valves, where possible, must be of one manufacturer. Valves must be designed for saturated steam working pressure of 861 Kpa (125 psi) and cold water non-shock working pressure of 1378 Kpa (200 psi) and must be manufactured and factory tested in accordance with the latest relevant British Standard or an equivalent Test Certificate must be submitted for all valves Seating surfaces of valves must be machined and finished to ensure tightness against leakage for the service specified and must seat freely Hand wheels of valves must be of suitable diameter to allow tight closure by hand with reasonable force without additional leverage and without damage to stem, seat or disc Valves located 2.4 m. or more above operating floor or platforms in plant rooms must be provided with a chain operated hand wheel Flanged valves must have flanges confirming to BS 4504-NP 16/11 or ANSI 125 or equivalent Cast iron body gate, globe and butterfly valves must be provided with position indicator All cast iron valves must be fitted with Cast Iron indexed hand wheel clearly marked "Open" and "Close" with an arrow to indicate the direction of rotation Gate Valves Gate Valves must be used for isolating purposes, as shown on the drawings must not be used for throttling purposes, such as regulating, balancing or controlling must be of double-faced solid wedge disc type giving straight-line flow Gate valves of sizes 2” mm and smaller must be of all bronze construction type with inside screw non-rising spindle, screwed bonnet, and screwed ends to ASTM B-61, B-62 or of gunmetal to BS 1400/LG2 Gate valves of size 2½” and larger must be of flanged bonnet and flanged ends, outside screw rising spindle type. Body, wedge and cover must be of cast iron, wedge facing rings and stem nut of gunmetal and spindle of aluminium bronze. Steam seal packing must be of high quality suitable for Kuwait climate. Gate valves of sizes 8” and larger must be equipped with bevel gear unit Globe Valves Globe valves must be used for throttling purposes to control the flow rate from full flow to complete shut-off Globe valves of size 2” and smaller must be of all bronze construction with inside screw rising spindle, screwed bonnet and screwed ends Globe valves of size 2½” and larger must have cast iron body, with outside screw aluminium bronze rising spindle, renewable gunmetal or bronze disc with gunmetal or bronze seat ring, flanged bonnet and flanged ends Globe valve disc must be of the beveled or parabolic shape to allow throttling Check Valves Check valves must be silent, spring actuated lift type used to prevent automatically reversing of flow at pump outlets, in vertical lines and as indicated in the drawings or as required elsewhere Check valves of sizes 2” and smaller must be of bronze construction, screwed ends Check valves of sizes 2½” and larger must be of cast iron or ductile iron body, wafer type, stainless steel or bronze disc stainless steel spring and renewable seats Butterfly Valves Butterfly valves must be used for shut-off or throttling purposes as shown on drawings Butterfly valves must be of rubber / EPDM lined tight shut-off type having ductile iron / ductile iron body, aluminium bronze disc high grade stainless steel shaft, bronze bearings, monel metal taper pins, buna-n seat liner vulcanized to the body The butterfly valves must be wafer type or flanged type Butterfly valves of 6” and smaller must have lever operator. Valves of 8” and larger must have manual gear operator. All butterfly valves must be supplied with locking device and position indicator Commissioning set must be provided on the return pipe of each water-cooling or heating coil and at other locations as shown on the drawings to facilitate balancing procedure. Commissioning set must consist of a double regulating valve for flow regulation and isolation and metering orifice station for measuring the pressure drop The metering station must have an integral square-edged orifice plate fitted with a pair of pressure test plugs, which can be connected to a manometer to measure the head loss. Bronze metering station must have cast-in flow direction marking, and threaded ends. The cast iron metering station must be supplied complete with two correctly sized gaskets and one set of flange bolting The double regulating valve must be of the Y-pattern Oblique globe type having a parabolic disc for allowing regular variation of the valve opening The variation of the opening is step controlled by a graduated adjustable sleeve fitted with the valve to control the lift of the disc Each opening position is indicated by a marked number on the sleeve At any pre-set position, the valve opening can still be regulated from fully closed to a maximum opening at the pre-set position The regulating sleeve is locked in the set position to prevent undesirable interference with the setting but remaining capable of being closed For size 2” and smaller Commissioning Set must be of all bronze or gunmetal construction screwed ends and rising stem double regulating valve fitted with numeric indicator For sizes 2½” and larger, Commissioning Set materials must be as follows 1) Metering Orifice Station Cast iron body, stainless steel orifice plate, gunmetal retaining bush and brass test plugs 2) Double Regulating Valve Cast iron body, Stainless steel or bronze rising stem, gunmetal disc gunmetal rings, anodized aluminium indicator plate and flanged ends Note: No need for a separate metering Station if the DRV is provided with flow measuring provision DRV with pressure tapping for flow measurement will be considered for approval instead of independent Metering Orifice Station Direct reading gauge with necessary hoses and other accessories must be supplied in a portable sturdy metallic or plastic casing for each size of valve used Strainers Strainers must be provided at the Suction side of each water circulating pump and at other locations as shown on drawings Strainers must be of Class 150 saturated steam-working pressure Strainers must be Y-type Strainers must be of same size as the connecting pipe Strainers for 2” pipe size and smaller must be bronze body with stainless steel screen and screwed ends Strainers for 2½” pipe and larger must be cast iron body with stainless steel screen and flanged ends Screen perforation must be as follows Pipe size 112 B Perforation size (mm) Number of perforations per Sq. Cm. 0 B Up to 2” 2½” and larger 0.8 1.6 64 23 Automatic Air Vents Automatic Air Vents must be provided at all high points of water piping system irrespective of whether indicated on drawings or not to permit venting any air collection at high points which tends to obstruct flow Automatic air vents must be of the float type, and construction must be as follows - Body and guide cross of bronze. - Valve seat, guide bush, upper and lower guide connecting rod valve and guide cone of brass or stainless steel - Float ball of stainless steel. - All automatic air vents must be installed with a suitable size shut-off valve في أمان الله