Mechanical Services Standard Specification Chilled Water Systems. May For ROYAL HOLLOWAY UNIVERSITY OF LONDON

Transcription

1 Mechanical Services Standard Specification Chilled Water Systems May 2010 For ROYAL HOLLOWAY UNIVERSITY OF LONDON

2 Prepared For The Estates Division By: Hulley & Kirkwood Consulting Engineers Ltd Castle House, Horizon Centre Upper High Street Epsom Surrey KT17 4RS (t): (f): (e): (w): Author: Checked: Approved: David Bantock/Andrew Wakelam Wayne Shipley Wayne Shipley Page 2

3 AMENDMENTS Author Date/Rev Description D Bantock / A Wakelam January 2010 Draft Issue W Shipley May 2010 Comments incorporated after meeting with RHUL Page 3

4 Index: 2.1 INTRODUCTION PIPEWORK General Pipework Preparation Fittings Dezincification Inaccessible Services Minimum Clearances Pipes Passing Through Walls Pipe Clearance Fire Rated Sleeves Supports Suspended Pipework Wall Mounted Pipework Spacing Expansion Devices Electrical Continuity (Expansion Devices) Care and Storage of Pipework Care of Pipes Gaskets and Fittings Open Ends Connectors Plant Items Draining, Venting and Isolating Requirements Drain Cocks Air Cocks Air Bottles Automatic Air Eliminators Pipework and Fittings Steel Pipework and Joints Steel Fittings Copper Pipework Joints and Fittings Plastic Pipework and Fittings Valves Isolating Valves Copper Installations (Isolating Valves) Balancing & Commissioning Valves Check Valves Drain Cocks Expansion Joints and Flexible Connections Strainers Manufacturers for Valves, Cocks and Strainers Automatic Air Vents Thermometers and Pressure Gauges...18 Page 4

5 2.1 INTRODUCTION This specification relates to the requirements for the supply and installation of chilled water systems operating at a minimum temperature of 5 o C and up to 10 bar g. ALL WORKS ARE TO BE INSPECTED BY THE TENDERING CONTRACTOR PRIOR TO PRICING HEALTH AND SAFETY STATEMENT Health and Safety precautions are required to be taken during the process of undertaking works within buildings cannot be underestimated. Reference shall be made to Royal Holloway University Health and Safety Policy and Contractors Guidance documents available from Royal Holloway University of London Estates Office. The Health and Safety Executive (HSE) publish a series of guidance documents regarding all many different methods of protecting the workforce and people in general when working with hazardous chemicals (COSH) and undertaking potential dangerous work activities. Also refer to the HVCA publication Worksafe guide to site safety (January 2003) Installers engaged in any work shall be registered with the Construction Skills Certificate Scheme (CSCS) and be in possession of a valid skills card. 2.2 PIPEWORK Page 5

6 2.2.1 General The Installers shall allow for installing services in a coordinated manner setting round obstructions to circumvent site difficulties which may not be obvious from the drawings as applicable issued with the works package. All pipework unless specifically identified shall be concealed and installed within false ceilings and architecturally designed service ducts. Pipework in visually exposed conditions shall be installed to have the neatest practicable finish. Pipes generally shall follow the contour of walls etc. Vertical pipes shall be plumb, without off-sets and be set close to local projections in order to follow their lines. No joints shall be made inside the thickness of walls, partitions, floors or ceilings. No pipework shall be concealed within walls or buried in floors Pipework Preparation Piping shall be cut clean and square with the axis of the pipe using a saw, pipe-cutting tool or machine deforming the pipe. Before installation all ends of the pipework shall be made square and smooth. All cutting oils and foreign bodies shall be removed from joints prior to assembly where steel threaded joints are used Fittings Pipe fittings shall be installed in such a manner that air or condensate cannot be trapped and pipes can be drained. Care shall be taken to avoid the defacing of fittings. Spanners of the correct size shall be used on all hexagons. Fittings shall be rejected if badly marked and the Installer shall replace such at his own expense Dezincification All fittings, valves, cocks, etc. except where otherwise specified (e.g. cast iron), shall be manufactured from copper, gunmetal, bronze or other agreed materials to prevent dezincification Inaccessible Services All steel pipework runs located within inaccessible areas (e.g. above plaster ceilings, obstructed by ductwork etc.), shall be welded, and all copper pipework shall be brazed. Screwed and flanged joints shall not be permitted in inaccessible locations. The emphasis shall be to avoid joints wherever possible. All pipework tube in contact with the soil or building fabric shall be protected by being twice wrapped in Denso tape or similar and equally agreed. Page 6

7 Minimum Clearances Pipes shall be installed so as to give the following minimum clearances between the pipe or lagging, and adjacent surfaces, as follows; Walls 25mm Ceilings 100mm Finished Floors 165mm Adjacent Pipes, both insulated 50mm Adjacent Pipes, both un-insulated 150mm Insulated Pipes to adjacent conduit or trunking 25mm Un-insulated Pipes to adjacent conduit or trunking 100mm Adjacent Pipes, one only insulated 75mm Un-insulated Pipes adjacent to electrical cables not in conduit or trunking Insulated Pipes adjacent to electrical cables not in conduit or trunking 150mm 100mm Under no circumstances shall pipes be spaced close together and enclosed in a common insulated covering. Not withstanding the above minimum clearances, sufficient clearance and segregation of services shall be allowed to ensure the following: That any thermal insulation can be applied easily That on flanged pipes the spacing is increased to accommodate the flanges and any insulated flange or valve boxes That access to pipes and electrical services is easy, both for installation and maintenance purposes. That segregation of services follow recommendations in Table 1 of BS8313: 1989: Ducts for Building Services Pipes Passing Through Walls All pipes passing through walls, floor, ceilings, partitions etc. shall be inserted through sleeves of similar material to the pipe provided as part of the installation works. In exposed to view areas eschutcheon plates shall be provided to conceal the sleeves Pipe Clearance Sleeves shall be free from internal burrs and shall have an internal diameter sufficient to allow the pipe to be fixed clear of the sleeve at all points, with at least 3mm gap between sleeve and pipe at all points. Page 7

8 Fire Rated Sleeves Pipes passing through internal walls, floors or partitions, which are fire barriers, shall have a fire sleeve that complies with the Building Regulations and tested to BS 476 for a minimum of 2 hours Wall Clearance Sleeves shall be of sufficient length to clear the face of finished wall or ceiling by at least 3mm Supports The Installer shall supply, fix and accurately set out all supports, bolts etc. necessary to suit the runs of pipework. The supports shall be suitable for the duty required and the areas in which the pipe is run. The type of support shall be dependant on location, type and size of the pipework Suspended Pipework Brackets shall consist of ball hanger assemblies comprising split pipe gland or one piece pipe clip, drop rod, locknut and male ball hanger. For copper pipework, brackets, clips and glands shall be manufactured from gunmetal or brass, for mild steel and galvanised steel pipework, they shall be of a similar material to the pipe. The Installer shall make his own fixings to the structure and prior to any works being undertaken the Installer shall agree the method of fixing to comply with the structural limitations and the requirements of Royal Holloway University of London Wall Mounted Pipework Brackets for vertical pipework shall be of the rigid type to guide the pipework and shall comprise a two piece pipe gland, locknut and screwed rod. For copper pipework, brackets, clips and glands shall be manufactured from gunmetal or brass, for mild steel and galvanised steel pipework, they shall be of a similar material to the pipe. Supports for pipework to be chrome plated shall be of similar finish but the support assembly shall comprise split pipe ring, extended nipple and back plate securely fixed to the structure. All brackets and hangers shall be installed with special attention to freedom for lengthways expansion, either in horizontal or vertical plane and to levels for air elimination and drainage. Supports for rise and drop pipes shall be arranged to allow freedom for expansion movement or horizontal runs. Pipes shall be adequately supported at bends, tees and where changes of direction occur. Vertical risers shall be supported at the base to withstand total weight. Branches from risers shall not be used as means of support for the riser. Valves 76mm and above shall be individually supported. Page 8

9 Where it is not practicable to use standard type brackets the Contractor shall supply and fix suitable purpose made supports to suit the position. All pipelines shall be separately supported and pipes slung from other pipes shall not be allowed. "Double" type hangers shall not be used due to the differential in expansion and contraction of the two pipelines and the difficulty of doing work on one pipeline without disturbing the other. All necessary metal supports, tees, angle or channel sections, screws, bolts etc. shall be provided and fixed by the Installer who shall be responsible for the accurate setting of same Spacing Note: Additional bracketry should also be considered where directional changes occur. Pipe Material Mild Steel Pipe Nominal Bore Intervals for Horizontal Runs mm m m Intervals for Vertical Runs Light Gauge Copper and above Plastic 16mm 20mm 25mm 32mm 40mm 50mm 67mm 75mm 90mm The support distances shall also be subject to the selected manufacturers recommendations and materials used. Page 9

10 Expansion Devices The Installer shall be responsible for the design of expansion systems for all heating services pipework as required. Expansion of pipework where possible shall be taken up by natural off-sets and changes of direction of pipe runs. Where this cannot be achieved, the Installer shall provide expansion loops, angular expansion compensators, and axial expansion compensators to suit. Adequate provision shall also be made at all connections to equipment and appliances to avoid stress due to contraction and expansion. This applies in particular to coils with copper headers Electrical Continuity (Expansion Devices) The pipework installations shall be electrically continuous up to and including the plant and equipment. The Installer shall provide and install earth bonding across all flexible joints including those on plant and equipment as necessary. If a mixture of steel, copper and plastic pipework is installed earth bonding of plant and all components shall be provided Care and Storage of Pipework It is imperative that a high standard of cleanliness is maintained to a standard in order that the cleanliness test as described in ASTM B Clause 12 can be maintained. The Installer shall at all times, using the accepted correct lifting tackle, take great care in offloading and handling pipes and fittings of all types so as to avoid damage to the material and any protective coatings or coverings. Suitable storage areas on site shall be agreed with the client and proper supports to carry pipework clear of the ground shall be used, particularly in damp areas and outdoors. The Installer shall provide suitable protection and/or covers for pipes stored outdoors in order to protect them from the weather and in the case of plastic pipework from solar degradation. Royal Holloway University of London shall reserve the right to reject or have rectified at the Installer's expense any damaged materials Care of Pipes Gaskets and Fittings The Installer shall at all times observe the installation and storage procedure as recommended by the Manufacturers. Gaskets shall be carefully stored to prevent damage. RHUL reserve the right to require any damaged materials to be removed from site Open Ends Care shall be exercised during the erection of pipework to ensure that foreign matter is not allowed to remain on or enter the pipes. When any portion of the installation is left open for any purpose whatsoever, the open end shall be temporarily sealed with purpose made plugs or blanking caps manufactured from sound wooden, metal or plastic materials. Rags, paper or similar substances shall not be used under any circumstances. A valve fitted at the end of a disconnected pipe shall not be considered satisfactory to prevent the ingress of foreign matter. All open ended pipework shall be permanently capped upon completion. Page 10

11 Failure to comply with this instruction shall mean that the Engineer shall have the right to instruct the Installer that pipework is left uncovered shall be dismantled and the pipework blownthrough and/or cleaned at no expense to Royal Holloway University of London Connectors Unless otherwise specified, pipelines up to and including 50mm connectors shall be unions, of materials suitable for the service and shall have bronze settings. In pipelines 65mm and above, connectors shall consist of flanges made of an appropriate material and specification as detailed elsewhere. Sockets and backnuts shall not be used under any circumstances Plant Items All connections to plant and equipment requiring internal inspection and maintenance shall be made using compatible coupling/flanges and positioned as to enable such inspections and maintenance readily and conveniently to be undertaken with the minimum disturbance of pipework and lagging Draining, Venting and Isolating Requirements All pipework shall be installed with sufficient gradient to ensure adequate venting and draining. The Installer shall be responsible for providing such draining and air release arrangements in the form of drain cocks or air vents, type as are specified and as are required to ensure that all sections and subsidiary sections of the installation can be completely drained and that air locks cannot form. Fittings for draining and venting shall be suitable for the working pressure of the systems to which they are connected Drain Cocks Drain cocks shall be positioned as necessary to completely drain the installation and sections as required. Drain cocks installed above floor level shall be fixed as unobtrusively as possible. Drain cocks shall be finished to match the pipework to which they are connected Air Cocks Air cocks shall be screw-down pattern with loose key, and shall be positioned as necessary to vent the installation. Cocks shall be finished to match the pipework to which they are connected Air Bottles Air bottles shall be of identical material to the service, and shall comprise a section of full bore pipe for 50mm pipes and below, and 50mm pipe for 65mm and above, not less than 150mm in length. Page 11

12 Each bottle shall be fitted with an air release line carried to low level with a suitable air release needle valve for venting. Vent pipes shall be 15mm size. Air bottles shall be positioned as required to facilitate adequate venting and shall be suitable for the system working pressure Automatic Air Eliminators Automatic Air Eliminators shall be of ball float type, and complete with isolating valves. They shall be positioned as required to enable adequate venting and shall be connected to the system on the inlet side by means of 15mm diameter pipes of material to suit the service, the outlet connection shall have a 15mm diameter copper discharge pipe carried to vent in an agreed position. Page 12

13 2.2.7 Pipework and Fittings The section of pipework and fittings for extensions or modifications to existing systems shall generally be of the same materials and generally traditional metal pipework. Where the Installer wishes to offer a different material, agreement shall be obtained from Royal Holloway University of London. All jointing methods and compounds shall be fully compatible with the materials being used including any water treatment chemicals present in the water system. Completely new systems shall be reviewed for the best choice of materials, be compatible with the building usage, and system operating requirements. The materials currently available include steel, copper and plastic selected to suit the operating temperatures, pressures and application. Jointing methods include, screwed, welded, grooved, press fit, solvent welded, fusion welded, soldered, brazed and compression Steel Pipework and Joints Steel pipework and joints shall be mild steel black medium weight or heavy weight manufactured in accordance with BS EN 10255: Joints shall be screwed or welded up to and including 50mm dia. Above this pipework shall be welded with flanged joints to be provided in accordance with BS EN Bolting of steel flanges shall be in accordance with BS EN Steel Fittings Steel fittings shall be in accordance with BS :2000 and 1256:2000 for malleable cast iron and copper alloy. Steel welded fittings shall be in accordance with BS EN :1999. Threaded fittings shall also be in accordance with BS Copper Pipework Joints and Fittings Copper pipework shall be light gauge in accordance with BS EN The following fittings and jointing methods may be applied to suit the application. (a) Capillary soldered fittings to BS EN 1254 Part 1 (b) Compression fittings to BS EN 1254 Part 2 (c) Push fit fittings (copper and plastic) to BS EN 1057 Note: Compression fittings also suitable for stainless steel chrome plated copper and polythene pipe may be used where required. Push fittings on stainless steel chrome plated copper pipes are not permitted. Suitable manufacturers shall be as Pegler/Yorkshire range, including Tectite, Kuterlite, Prestex and XPress. Page 13

14 Plastic Pipework and Fittings Valves There are several plastic pipe and fitting products currently on the market which have been tried, tested and approved for use with chilled water systems operating at temperatures of 20 o C max. It is important that products are not mixed in anyway and strict adherence to the manufacturer s specific instruction must be applied at all times. Durapipe UK Ltd supply and manufacturer a Durapipe Superflo System which includes fittings and valves for use on chilled water systems operating up to a maximum temperature of 20 o C (chilled water). The application of this product shall be as agreed with Royal Holloway University of London and the particular application. Alternative manufacturers may be considered but shall be equal and agreed to the satisfaction of Royal Holloway University of London. The Installer shall supply and install valves to enable isolation, flushing, cleaning and balancing of the systems as required. All valves should be as those manufactured by Crane, Hattersley, Oventrop or equal and agreed and be in accordance with the approved British Standards Isolating Valves Valve shall be of the gate or ball type with hand wheel, lever or lockshield to suit the application. For steel up to and including 50mmdia. valves shall be screwed and have bronze bodies. Gate valves shall be manufactured to BS EN Ball valves shall be manufactured to BS EN 1982 with PTFE seating and packing. For valves of sizes 50mm and above they shall be of the gate or butterfly type with flanged connections. Gate valves shall be manufactured to BS EN 1171 with cast iron bodies. Butterfly valves shall be manufactured be to BS EN 593 with ductile iron bodies Copper Installations (Isolating Valves) Valves shall be of the gate or ball type with handwheel, lever or lockshield to suit the application. The valves shall have compression ends in accordance with BS 1057 table 4 (15-54mm) Balancing & Commissioning Valves Valves shall be of the double regulating type with fixed orifice. Bronze valves shall be in accordance with BS EN 1254/2. Ductile Iron valves shall be in accordance with BS EN 1092 Page 14

15 Check Valves Check valves where required shall conform to BS 5154 (Bronze) or BS EN (Cast Iron) Drain Cocks Drain cocks shall be bronze conforming to BS and where required incorporate hose union outlet Expansion Joints and Flexible Connections Expansion joints shall be selected specifically for the application and be as manufactured by Engineering Appliances or equal agreed. Each joint shall be anchored and guided in accordance with the manufacturers instructions. Flexible connections where required shall be as manufactured by Engineering Appliances or equal agreed and be selected to suit the application. Connections to pumps and plant shall use the tied type connections Strainers Pipeline strainers shall be provided as specified and shall be Bronze to BS EN 1982 for sizes 15-50mm inclusive and Cast Iron to BS EN 1561 for sizes above 50mm dia.strainers shall be fitted with 304 stainless steel 40 mesh screens. Page 15

16 2.2.9 Manufacturers for Valves, Cocks and Strainers The following tables are provided to guide the Installer in respect of listed manufacturers who manufacture products in compliance with the appropriate British Standards and relevant Water Regulations (WRAS). The list is not exhaustive and alternative manufacturers may be considered if they comply with the required standards. VALVES Suitable Valves: SERVICE DUTY SIZE TYPE JOINTS CHW Flow isolation Up to 50mm Copper alloy gate valve BS5154 Screwed Hattersley: Crane: Fig 33X D151 65mm and above Cast iron gate valve BS5150 Hattersley: M540 PN6 Crane: FM 52 Flanged to BS4504 Table 10 CHW Flow regulation and measurement Up to 50mm Orifice valves - Copper alloy pressure tapped variable orifice double regulating valves to BS7350. Screwed Hattersley: Fig 1700 Fig 1700L (low flow) Crane: D930 D932 (low flow) 65mm and above Orifice Valves - Cast iron pressure tapped variable orifice double regulating valves to BS7350. Flanged to BS4504 Table 10 Hattersley: Crane: Fig M737 DM930 CHW Safety Valves Up to 50mm NABIC Fig 500 type spring loaded Screwed Page 16

17 CHW Flow regulation and measurement Up to 50mm Commissioning Stations - Copper alloy double regulating valve and orifice plate close coupled Screwed Hattersley: FIG 2432 Fig 2473L (low flow) Crane: D941 D942 (low flow) 65mm and above CHW Flow regulation Up to 50mm Commissioning Stations - Cast iron double regulating valve and orifice plate close coupled. Hattersley: Crane: Copper alloy double regulating valve. M2733 DM941 Hattersley: Fig 1432 Fig 1473 (low flow) Flanged to BS4504 Table 10 Screwed Crane: D920 D921 (low flow) 65mm and above Cast iron double regulating valve. Hattersley: Crane: Fig M733DR DM920 Flanged to BS4504 Table 10 CHW Non return valves Up to 50mm Copper Alloy Hattersley: Crane: Fig3048 Equivalent Screwed 65mm and above Cast Iron Hattersley: Crane: M651 PN16 F479 Flanged CHW Strainers Up to 50mm 65mm and above Copper alloy pipeline type oblique. Hattersley: Fig 807 Crane: D297 Cast iron pipeline type oblique Hattersley: Fig 810 Crane: FM276 Screwed Flanged Page 17

18 NOTES: 1. All valves excluding commissioning/control and motorised control valves to be full line size unless specifically noted otherwise on the drawings or commissioning valve schedules. Commissioning/control and motorised valves shall be selected by the Installer to suit the respective flow rate and to in accordance with the manufacturer s recommendations Automatic Air Vents Automatic air vents shall be of high quality brass alloy as manufactured by Spirax Sarco AE30B (with lockshield valve). These valves comply with BSEN and the European Pressure Directive 97/29/EC Thermometers and Pressure Gauges Thermometers shall be of the dial type, very robust and operating on the bi-metallic coil principle, complete with pipeline pocket (extended type for insulation). The thermometers shall have a stainless steel body and 100mm glass faced dial. The temperature range shall be from 0-30 o C. Pressure gauges shall be of the Bourdon tube dial type with clear Perspex face and pressed metal casing (100mm dia.) with units worked in bar and psi. The selected range shall suit the system operating pressure with the system pressure selected for a mid range reading. The gauges shall be supplied complete with gauge cock and ring or U siphon. The gauge shall be compliant with the requirements of the Pressure Equipment Directive 97/25/EC. Page 18