M000 – Mechanical Engineering

M000 – Mechanical Engineering Contents Page No. TOC \o "1-3" \t "AppendixHeader,1" 1 INTRODUCTION PAGEREF _TOC46060757 \H 1 2 MATERIALS AND EQUIPMENT PAGEREF _TOC46060758 \H 1 2.1 Standards and Submission of Materials PAGEREF _Toc46060759 \h 1 2.2 Lifting Equipment and Pressure Systems PAGEREF _Toc46060760 \h 2 2.3 Steel Pipes and Fittings PAGEREF _Toc46060761 \h 2 2.4 Ductile Iron Pipes and Fittings PAGEREF _Toc46060762 \h 2 2.5 Unplasticized PVC Pipes and Fittings PAGEREF _Toc46060763 \h 2 2.6 Polyethylene Pipes and Fittings PAGEREF _Toc46060764 \h 3 2.7 Propylene Copolymer Pressure Pipes PAGEREF _Toc46060765 \h 3 2.8 Service Size Water Fittings and Appliances PAGEREF _Toc46060766 \h 3 2.9 PTFE Tape PAGEREF _Toc46060767 \h 5 2.10 Joint Seals and Lubricants PAGEREF _Toc46060768 \h 5 2.11 Flanges for Pipes and Pipeline Fittings PAGEREF _Toc46060769 \h 5 2.12 Gaskets for Flanged Joints PAGEREF _Toc46060770 \h 5 2.13 Valves and Penstocks PAGEREF _Toc46060771 \h 5 2.14 Structural Steelwork PAGEREF _Toc46060772 \h 7 2.15 Wrought Aluminium and Aluminium Alloy PAGEREF _Toc46060773 \h 8 2.16 Cylindrical Steel Process Vessels PAGEREF _Toc46060774 \h 8 2.17 Welding PAGEREF _Toc46060775 \h 8 2.18 Nuts, Screws, Washers, Bolts, Fixings and Fastenings PAGEREF _Toc46060776 \h 9 2.19 Handrails and Balusters PAGEREF _Toc46060777 \h 11 2.20 Stairs and Ladders PAGEREF _Toc46060778 \h 11 2.21 Flooring, Walkways and Stair Treads PAGEREF _Toc46060779 \h 12 2.22 Metals for Mechanical Plant PAGEREF _Toc46060780 \h 12 2.23 Machinery: General PAGEREF _Toc46060781 \h 13 2.24 Lubricants PAGEREF _Toc46060782 \h 13 2.25 Lubrication Systems PAGEREF _Toc46060783 \h 14 2.26 Pumps : General PAGEREF _Toc46060784 \h 14 2.27 Fibre Reinforced Plastics (FRP) PAGEREF _Toc46060785 \h 15 2.28 Protective Coatings to Metalwork PAGEREF _Toc46060786 \h 15 2.29 Timber PAGEREF _Toc46060787 \h 16 2.30 Pressure Gauges PAGEREF _Toc46060788 \h 16 3 INSTALLATION OF EQUIPMENT PAGEREF _TOC46060789 \H 17 3.1 Setting of Machinery PAGEREF _Toc46060790 \h 17 3.2 Pipework PAGEREF _Toc46060791 \h 17 3.3 Pipework Supports PAGEREF _Toc46060792 \h 18 3.4 Pipe Jointing PAGEREF _Toc46060793 \h 18 3.5 Welded Joints in Plastic Pipes PAGEREF _Toc46060794 \h 18 3.6 Sealing of Ducts PAGEREF _Toc46060795 \h 18 3.7 Pressure Testing of Pipework PAGEREF _Toc46060796 \h 19 4 DESIGN PAGEREF _TOC46060797 \H 19 4.1 Design Standards PAGEREF _Toc46060798 \h 19 4.2 Equipment Selection and Design PAGEREF _Toc46060799 \h 19 4.3 Hazardous Areas PAGEREF _Toc46060800 \h 20 4.4 Hydraulic System Design PAGEREF _Toc46060801 \h 20 4.5 Noise and vibration PAGEREF _Toc46060802 \h 21 INTRODUCTION The mechanical requirements should be read in conjunction with the CONTRACT specific specification requirements for the Project. MATERIALS AND EQUIPMENT Standards and Submission of Materials 2.1.1 CONTRACTOR shall submit a list of his proposed suppliers and sources of materials required for the execution of the Works to CPA for his approval prior to placing orders for material. 2.1.2 Names of additional suppliers and sources may be submitted by CONTRACTOR during the execution of the CONTRACT, but no approved source of supply shall be changed without the agreement of CPA. 2.1.3 Where proprietary products are specified, “or equal” products from other manufacturers will be permitted with the approval of CPA. 2.1.4 CONTRACTOR shall comply with the appropriate American, European or British Standard Specification or Water Industry Specification. 2.1.5 Where CPA has preference on subjective choices within standards these have been specified below. Where no choice is stated CONTRACTOR shall submit his proposal for approval by CPA. 2.1.6 All materials, so far as is practicable, shall be of Western origin, and all manufactured articles shall be of Western manufacture unless otherwise agreed. 2.1.7 Materials shall be obtained from Manufacturers operating a quality system in compliance with BS EN ISO 9002 or equal. 2.1.8 Samples of the material shall be taken in accordance with the appropriate Standard where applicable. 2.1.9 The materials subsequently supplied shall conform to the quality of samples which have been approved by CPA. 2.1.11 All plant and materials shall be suitable for use at ambient temperatures of 0 to 50°C when outside and 0 to 45°C inside. 2.1.12 Pipework, vessels and equipment shall, where necessary, be trace heated, insulated and suitably clad to protect personnel from exposure to excessive surface temperatures or to prevent contents from freezing. Insulation work shall be carried out in accordance with BS 5970, Code of Practice for Thermal Insulation of Pipework and Fittings. Insulating materials shall comply with the requirements of BS 3958, Part 4 - "Thermal Insulating Materials", and BS 5422, - "Method for specifying thermal insulating materials on pipes, ductwork and equipment (in the temperature range of -40°C to +700°C)" or equivalent European Standards. Insulation shall not be applied to pipework until all pipework pressure testing has been completed. Lifting Equipment and Pressure Systems 2.2.1 All permanent lifting equipment and pressure systems must be registered with the Client. CONTRACTOR shall inform CPA of his intention to supply all such equipment and systems as early after award of CONTRACT as possible. CPA will obtain the plant identification number from the Client. CONTRACTOR will be advised of the plant identification number for stamping, printing or otherwise fixing as directed by CPA to the equipment after the completion of site testing. 2.2.2 For pressure systems subject to statutory regulations CONTRACTOR shall arrange for inspection and production of a Written Scheme of Examination (WSE) by the Client’s third party competent inspection authority, as required under the Pressure Systems and Transportable Gas Containers Regulations 1989. Two copies of the WSE shall be submitted to CPA. On receipt of the WSE CPA shall arrange for the free issue of an “identification pack” by the Client. CONTRACTOR shall securely fix the items in the identification pack to the relevant equipment. Steel Pipes and Fittings 2.3.1 Mild/carbon steel pipes, fittings and joints shall conform to the relevant provisions of BS 534 and BS 3601. Mild/carbon steel screwed pipes and fittings shall be galvanised heavy gauge to BS 1387 with threads to BS 21. They shall not be used for potable water. Stainless steel tubes and fittings shall conform to the relevant provisions of BS 4285 or BS 3605. Ductile Iron Pipes and Fittings Ductile iron pipes, fittings and joints shall comply with the following standards: Application BS Water Pipelines Sewerage EN 545 EN 598 Unplasticized PVC Pipes and Fittings 2.5.1 Unplasticized PVC pressure pipes, joints and fittings shall comply with the relevant provisions as set out below: Material Pipe Joints and Fittings PVC-U (Imperial Grey) BS 3505 BS 4346: Pt 1, 3 (solvent welded) Pt 2 (mechanical) PVC-U (Metric Blue) WIS 4-31-06 WIS 4-31-07 MOPVC WIS 4-31-08 BS 4346 WIS 4-31-07 2.5.2 Modified polyvinyl chloride (mPVC) pipes, fittings and joints shall comply with the requirements of North West Water document ‘General Specification - Modified (mPVC) Pressure Pipes and Fittings’ 2.5.3 Solvent cements for jointing unplasticized PVC pipes shall comply with BS 4346: Part 3. Polyethylene Pipes and Fittings 2.6.1 Blue polyethylene pipe up to nominal size 63 for below ground use for potable water shall comply with the relevant provisions of BS 6572. 2.6.2 Polyethylene pressure pipes for use for cold potable water or sewage in nominal sizes greater than 63 shall comply with the relevant provisions as set-out in the following table, except that for sewage rising mains below ground the colour shall be black. Material Pipe WIS No PE 80 (MDPE) (below ground) Blue 4-32-03 PE 80 (MDPE) (above ground) Black 4-32-09 PE 100 (HPPE) (below ground) Blue 4-32-13 2.6.3 Polyethylene fusion joints and fittings for use with cold potable water shall comply with relevant provisions of WIS No 4-32-14 and WIS 4-32-15. 2.6.4 Mechanical joints and fittings for polyethylene pipes for use with cold potable water shall comply with WIS 4-24-01. Propylene Copolymer Pressure Pipes 2.7.1 Propylene copolymer pressure pipe shall comply with the relevant provisions of BS 4991 and, where in contact with potable water, shall be Series 1. Service Size Water Fittings and Appliances 2.8.1 Service size water fittings and appliances shall comply with the relevant provisions of the appropriate specification, as set out in the following table. 2.8.2 Capillary fittings shall be of the integral solder ring pattern. Type A or B compression fittings shall be used with half-hard pipes. Types A or B compression fittings for use on underground pipework shall be of gun metal alloy. 2.8.3 Supports to copper pipes shall be flanged brass clips with countersunk brass woodscrews. 2.8.4 Chromium plating to exposed copper piping and fittings shall comply with BS EN 12540, Classification No Cu/Ni20b Crr. 2.8.5 Pipe fittings for use with polyethylene tubing shall be compression fittings of copper, copper alloy or plastics. Supports to plastic pipes shall be polypropylene clips. TABLE 2.8.6 Water Fitting/ Appliance Type/Material BS/WIS No Service pipes, pump delivery pipes, distributing pipes and fittings Draining taps Draw-off taps Stopvalves Float operated valves Floats for ballvalves Storage cisterns and lids Wash basins Sinks WC pans Connectors for WC pans WC seats and covers WC flushing cisterns Urinals Automatic flushing cisterns for urinals Ferrules Copper Capillary and compression fittings for copper tubes Polyethylene Copper and copper alloy compression fittings for polyethylene pipes Joints and fittings for polyethylene pipes (performance) PVC-U PVC-U joints and fittings (solvent welded) PVC-U joints and fittings (mechanical) Screw-down pattern Metal or plastics bodied (performance) Above-ground, screw-down pattern Underground Diaphragm type (copper alloy body) Diaphragm type (plastics body) Copper Plastics Low carbon steel Polyolefin or olefin copolymer Ceramic Metal hand rinse Glazed fireclay Stainless steel Horizontal outlet Plastics Plastics, Type 1 Dual flush type Stainless steel slab Vitreous china bowl Lidded Various EN 1057 EN 1254-1&2 6572 WIS No 4-22-01 and 4-32-11 EN 1254-3 5114 3505 4346: Part 1 4346: Part 2 2879 5412 1010: Part 2 5433 WIS No 4-23-04 1212: Part 2 1212: Part 3 1968 2456 417: Part 2 4213 1188 EN 111 1206 1244: Part 2 EN33/EN57/EN997 5627 1254 1125 4880: Part 1 5520 1876 WIS No 4-22-02 PTFE Tape 2.9.1 Unsintered polytetrafluoroethylene (PTFE) tape for thread sealing applications shall comply with BS 7786. Joint Seals and Lubricants 2.10.1 Elastomeric joint seals for water mains and drainage purposes shall be Types WA and WG respectively, complying with the relevant provisions of BS EN 681-1 and shall be obtained from the pipe manufacturer. 2.10.2 Joint lubricants for sliding joints shall have no deleterious effects on either the joint rings or pipes, and be unaffected by the liquid to be conveyed. Lubricants to be used for jointing water mains shall not impart to water taste, colour, or any effect known to be injurious to health, and shall be resistant to bacterial growth. Flanges for Pipes and Pipeline Fittings 2.11.1 Flanges for pipe and pipeline fittings shall, unless otherwise required by the CONTRACT, comply with BS 4504 Section 3.1 and BS EN 1092-2 for 16-bar nominal pressure rating. 2.11.2 Flanges for thermoplastics pipes shall have galvanised steel backing rings. Gaskets for Flanged Joints 2.12.1 Gaskets for flanged pipe joints shall be of the inside-bolt-circle type. The dimensions of gaskets shall comply with BS EN 1514-1. Gaskets shall be manufactured from material complying with the provisions of BS EN 681-1 Type WA rings. Valves and Penstocks 2.13.1 Valves and penstocks shall comply with the relevant provisions of the appropriate British Standards as listed below and modified by the following clauses: Type BS Cast iron gate valves Predominantly key-operated cast iron gate valves for waterworks purpose Cast iron gate (parallel slide) valves Cast iron check valves Copper alloy globe, stop and check, check and gate valves Butterfly valves Diaphragm valve Cast iron plug valves Cast iron and carbon steel ball valves for
 general purposes Penstocks 5150 5163 5151 EN 12334 5154 EN 593 5156 5158 5159 7775 Valve parts to be in contact with potable water shall meet the relevant provisions as set out below: Type BS/WIS No Metallic Non-metallic 7766 6920 IGN No 5-01-02 Valve extension spindles shall be solid galvanised mild steel, fabricated in single lengths. Any lengths stated or shown are approximate only and CONTRACTOR shall be responsible for obtaining the exact length. The maximum length between guides shall be 2m. Extension spindles and caps for buried valves shall terminate within 200mm of finished ground level. Within structures, extended spindles shall terminate not more than 200mm below the relevant operating surface. Handwheels, valve caps and spindle couplings shall be positively located and secured on spindles/shafts. Friction location shall not be accepted. Operating handwheels shall have the direction of open/close operation cast, stamped, or otherwise permanently marked upon the handwheel rim. Handwheels shall be sized to enable the valve to be operated against the maximum operational differential pressure or a minimum of one bar, whichever is the greater, with an operating effort at the rim (push/pull) not exceeding 250N. Where situated remote from the valve, operating handwheels shall be positioned at a nominal height of 1m above operating floor level. Extension spindles shall be supported by means of guide brackets/floor pedestals. Lever-operated valves shall require a force not exceeding 250N, applied at the lever, to open or close the valve. In the open position the lever shall be parallel to the direction of flow. In the closed position the lever shall be at right angles to the direction of flow. The lever shall be lockable in both open and closed positions Remote mounted actuators shall be mounted on a floor pedestal and shall be provided with drive shafts between valve and actuator units complete with all necessary universal joints and shaft support bearing brackets. Provision shall be made for the necessary lubrication of all universal joints/bearing points in an extended valve drive shaft assembly. Lubrication facilities shall be in the form of grease nipples or grease filled protective gaiters as appropriate. Guards shall be designed such that universal joints and other serviceable areas are readily accessible without dismantling the headstock or valve unit. Guards may be split along the longitudinal axis or be of telescopic design. Valves shall normally be designed for clockwise closing. On networks and trunk mains CONTRACTOR shall check the direction of closing required as this may vary. Valves shall be capable of being locked in their operating and isolation position to prevent unauthorised use of the valves. Valves fitted with a handwheel shall incorporate a locking bracket for use with a padlock or padlock and chain. Valves fitted with valve caps shall be provided with a lockable cap. All devices shall be easily removed when unlocked and captive to prevent loss of the device. Non-return valves shall be mounted in the horizontal plane unless otherwise agreed with CPA. Non-return valves less than 80mm shall be bronze swing check pattern in accordance with BS 5154 and screwed to BS21. Valve rating shall be 16 bar minimum. Non-return valves 80mm and larger shall be cast iron swing check pattern in accordance with BS EN 12334 with flanges to BS 4504 Section 3.1 & BS EN 1092-2. Valve rating shall be 16 bar minimum. Valve bodies shall be fitted with an inspection cover. Inspection covers shall have tapped bosses fitted with galvanised plugs. Non-return valves shall be supplied with a limit switch mounting plate, external lever and counterweight, and fully enclosed in a guard compliant with PD 5304, unless otherwise specified. Quarter-turn eccentric plug valve bodies shall be manufactured in close-grained cast iron with integrally-cast flanges. The valve plug shall be non-lubricated, the external surface of the plug being coated with an abrasion resistant elastomer, and the resilient seating shall be designed to provide a drop-tight shut-off to flow in either direction. The plug shall be designed without a centre spindle to avoid the accumulation of rags and screenings (where applicable). The valve bearings shall be designed to prevent ingress of abrasive material. Penstocks shall be constructed, as appropriate, from the material combinations CF1, PL1, or MF1, as defined within BS 7775. Composite plastic and lightweight fabricated penstocks shall not be selected for river intake, lockgate, inlet works, or other such duties where the gate may be liable to damage from large solid objects entrained in the flow. Butterfly valves shall not be used for crude sewage, sludges or lime slurries. Knife gate valves shall be fitted with stainless steel gates designed to cut through solids in the flow. Each valve shall present a virtually full bore opening to the flow when fully open, free from obstruction, or a seat pocket where solids can accumulate and give rise to solids compaction when the valve is being closed. The body/gate seal shall be located outside the fluid flow so as to be protected from erosive/abrasive solids in the flow and shall provide a bubbletight shut-off. Structural Steelwork 2.14.1 Structural steelwork shall be designed to BS 449 : Part 2 or BS 5950 or DD ENV 1993: Part 1. Steel sections shall comply with the relevant provisions of the appropriate British Standard, as set out below: Type BS Structural steel sections Cold rolled steel sections Weldable structural steels Hot-rolled structural steel angles Hot-rolled structural hollow sections Steel tubes for general purposes 4: Part 1 2994 EN 10025 EN 10056-1 EN 10210: Part 2 6323: Parts 2 - 7 Wrought Aluminium and Aluminium Alloy 2.15.1 Wrought aluminium and aluminium alloys shall comply with the relevant provisions of the appropriate British Standard, as set out below. Maximium deflection of aluminium structural sections shall be span/200.: Type BS Sections for structural purposes Plate, sheet and strip Drawn tube Bars, extruded round tubes and sections Ingots and castings 1161 EN 485 and EN 573 EN 515, EN 573-3,4, EN 754-1,2,7&8 1474 or EN 755: Parts 3 - 6 EN 1559-1/EN1559-4, EN1676 & EN1706 Cylindrical Steel Process Vessels 2.16.1 Horizontal cylindrical steel vessels shall be designed in accordance with BS 2594:1975. Manways shall be designed to allow safe access into the vessel and adequate provision shall be included in the CONTRACT supply for the safe lifting and removal of manway covers. Welding 2.17.1 Site welding shall be minimised. 2.17.2 Electrodes for the manual metal-arc welding of carbon and carbon manganese steel and stainless steel shall comply with the relevant provisions of BS EN 499 and EN 1600 respectively. 2.17.3 Electrode wires and fluxes for the submerged arc welding of carbon steel and medium tensile steel shall comply with relevant provisions of BS EN 756 and BS EN 760 respectively. 2.17.4 Filler rods and wires for gas-shielded arc welding of ferritic steel, austenitic stainless steel and aluminium and aluminium alloy shall comply with the provisions of BS EN 440 and BS EN 12072-2. 2.17.5 Manual welding of stainless steel shall be by the inert gas tungsten-arc process. Welding of stainless steel pipework shall comply with BS4677. Heat tint shall be removed from weld affected areas. A chemical cleaning method compliant with ASTM Standard Practice A380 shall be used. Mechanical surface abrasion techniques shall only be used with the prior approval of CPA. 2.17.6 CONTRACTOR shall submit details of the proposed welding and welding repair procedures and reference standards. Test welds using these procedures and standards shall be made by CONTRACTOR under simulated site conditions. Welding procedure qualification records (WPQR) to BS EN 288 : Part 3 shall be submitted to CPA. The WPQR shall be used by CONTRACTOR to develop a weld procedure specification (WPS) describing in detail how a particular weld is to be made. 2.17.7 Welders shall only make welds for which they are approved. Welder qualifications to BS EN 287: Part 1 shall be submitted to CPA. 2.17.8 Joints shall be tested using non-destructive testing (NDT) techniques, unless it is necessary to use destructive testing to achieve adequate interpretation. 2.17.9 The following general points shall be complied with: Cutting shall be done by shearing, chipping, grinding, machining, thermal cutting or thermal gouging. When shearing is used the effect of work hardening shall be taken into account and precautions shall be taken to ensure that there is no cracking of the edges. Any other cutting process shall not be used without approval of CPA. Holes for branches of 25mm and below shall be drilled. All weldment areas shall be cleaned back to bright sound metal prior to welding. Workshop areas used for stainless steel welding shall be segregated to avoid contamination. All welds shall be continuous, proud of the surface, free from cracks undercuts and spatter, and shall blend smoothly into the parent material without any pronounced humps or craters. Peening of welds or the use of weld spatter release agents shall not be permitted. All root runs in pipes up to and including 150mm nominal diameter shall be deposited by the TIG process, incorporating a high frequency (HF) arc initiation and crater fill device. Backing material shall not be permitted. This takes precedence over the relevant British or European Standard. Any arc strikes shall be removed by grinding and checked by non-destructive testing. When interpreting NDT findings of welds made in castings and ductile iron, consideration shall be given to allowable defects in the parent material. Cross checking of NDT reports by CPA will be random and solely at the discretion of CPA. A discrepancy rate of 2% or greater between CPA's findings and those reported by CONTRACTOR in the relevant NDT reports may result in CPA initiating a 100% check of all NDT results. All discrepancies found shall be reported to CONTRACTOR by CPA along with written instructions to remedy all discrepancies and deficiencies. 2.17.10 Welded components shall be stress relieved prior to machining. Nuts, Screws, Washers, Bolts, Fixings and Fastenings 2.18.1 Mild and high strength nuts, screws, washers and bolts shall comply with the relevant provisions of the appropriate British Standard, as set out below: Type BS Black hexagon bolts, screws and nuts Metal washers for general purposes High strength friction grip bolts, nuts and washers 4190 4320 4395: Parts 1 and 2 2.18.2 Mild steel nuts, bolts and washers for use in non-immersed applications shall be sherardized or galvanised. For immersed conditions, stainless steel fixings shall be used. Stainless steel nuts, screws, washers, bolts, fixings and fastenings shall be manufactured from Grade X5CrNiMo17-12-2 steel to BS EN 10088. 2.18.3 Mild steel and high tensile steel proprietary fixings, other than those specified in 2.18.2, shall be protected in accordance with the relevant provisions of the appropriate British Standard, as set out below: Type of Fixing Type of Protection Cast-In, having no machined thread Cast-In/Expanding, basic major diameter of machined thread Not Exceeding 19mm Exceeding 19mm Hot-dip galvanised Electroplated cadmium Electroplated zinc EN ISO 1460 BS EN 12330, Cd 25/C or D BS EN 12329, Zn 25/C or D - BS 3382 : Pt 1 BS 3382 : Pt 2 - BS EN 12330, Cd 25/C or D BS EN 12329, Zn 25/C or D 2.18.4 Bolting for pipes and fittings shall comply with the relevant provisions of BS 4504: Sections 3.1 and BS EN 1092: Part 2 except that spheroidal graphite iron bolts for use with ductile iron pipes and fittings shall be manufactured from metal complying with the provisions of BS EN 1563 for Grade EN-JS 1050. 2.18.5 Bolts shall be supplied such that when assembled and fully tightened the nut shall be totally engaged with no more than three threads protruding. Bolts shall be supplied to finished length. Cutting of finished bolts to required length shall not permitted. 2.18.6 Where fixings or fastenings in contact with the material being fixed may give rise to detrimental galvanic action/corrosion within the Asset Design Life, suitable isolating washers and sleeves shall be used. 2.18.7 All nut and bolt assemblies, shall incorporate a single washer placed between the fixed surface and the component (usually the nut) to be tightened. Where appropriate tapered washers shall be used to ensure full face contact. 2.18.8 Fixings into concrete shall be of the chemical anchor type unless alternative fixings are specified by the equipment manufacturer or in the CONTRACT specific specification. On fixings and fasteners which may be subject to vibration an approved method of locking shall be incorporated. 2.18.9 Where required by the CONTRACT, axial and shear loading tests on structural fixings in concrete or masonry shall be carried out in accordance with the provisions of BS 5080. The safe working load shall be as described in the CONTRACT. 2.18.10 Fixings and fasteners for use on demountable components, except where in contact with potable water, shall have an anti-seize compound applied to the threaded section. Handrails and Balusters 2.19.1 Protective barriers shall comply with the provisions of BS 5395: Part 3. Handrailing shall be designed for a minimum design imposed load value of 0.36kN/m run. 2.19.2 Untensioned chains, ropes or other non-rigid materials shall not be used as protective barriers. Self–closing gates shall be provided at access openings in handrails. 2.19.3 Handrails and balusters shall be manufactured from material complying with the relevant provisions of the appropriate British Standard, as set out below. Material Handrails Balusters Solid Tubular Solid Tubular  BS Grade BS Grade BS Grade BS GradeMild Steel Stainless Steel Aluminium EN 10025 EN 10088 Pt 2 EN 755 Pt 1-6 S275 X5CrNiMo 17-12-2 6082 1387 or 6323 Pt 2 6323 Pt 8 EN 755 Pt 1-6 or EN 754 Pt 1&2 - HFW2 - 6082 6082 EN 10025 - EN 10088 Pt 2 EN 1676 or EN1706 S275 - X5CrNiMo 17-12-2 LM6 1387 or 6323 Pt 2 6323 Pt 8 EN 755 Pt 1-6 or EN 754 Pt 1&2 - HFW2 - 6082 6082 2.19.4 Mild steel handrailing shall be galvanised after manufacture. Aluminium handrails and balusters shall be anodised to BS 1615, Grade AA25. 2.19.5 Handrailing shall consist of two rails in the same vertical plane. The upper (hand) rail shall be positioned at a vertical height above walkway level of 1100mm. For stairways this dimension shall be 900mm taken from the stair pitch line. The lower (knee) rail shall be positioned midway between the top rail and the walkway/stair pitch line or the top of the toeplate/upstand. Handrailing shall be of circular cross-section. 2.19.6 Toeplates shall be 100mm high installed with a 15mm space between the underside of the toeplate and the walkway. 2.19.7 Fixings for galvanised mild steel handrails and balusters shall be mild steel sherardized or galvanised. 2.19.8 Fixings for GRP standards and fittings shall be grade X5CrNiMo 17-12-2 stainless steel to BS EN 10088: Part 2. Stairs and Ladders 2.20.1 Stairs and ladders shall be designed to the requirements of BS 5395: Parts 1 & 3. Stairs shall be designed as being semi-public. The clear width of stairs shall be suitable for the intended use with a minimum of 800mm. Ships ladders shall not be permitted. 2.20.2 After fabrication, mild/carbon steel ladders and stairs shall be galvanised. 2.20.3 Stainless steel ladders and stairs shall be fabricated from grade X5CrNiMo 17-12-2 stainless steel to BS EN 10088: Part 2. 2.20.4 Aluminium ladders and stairs shall be fabricated from Grade 6082 aluminium complying with BS 1474 then anodised to BS 1615, Grade AA25. Flooring, Walkways and Stair Treads 2.21.1 Flooring, walkways and stair treads shall comply with the relevant provisions of BS 4592. 2.21.2 As a minimum, flooring shall be designed to a uniformly distributed imposed load of 5kN/m2 (unfactored). 2.21.3 After fabrication, mild/carbon steel flooring, walkways and stair treads shall be galvanised. 2.21.4 Clips and fixings for GRP flooring shall be grade X5CrNiMo 17-12-2 stainless steel to BS EN 10088: Part 2. 2.21.5 Individual floor panels shall be bolted down to prevent unauthorised removal. In addition, panels shall be prevented from sliding sideways when adjacent panels are removed, by means of permanent steelwork or non-removable locating studs. 2.21.6 Where regular access is required through flooring, hinged type covers with locking stays shall be supplied. Metals for Mechanical Plant 2.22.1 Metals used for the construction of mechanical plant shall comply with the relevant provisions of the standards set out below. Cast Iron BS EN 1561 Stainless Steel for machining for lightweight fabrication for aggressive environments BS EN 10088 : Part 2 Grade X8CrNiS 18-9 Grade X2CrNiN 18-10 Grade X5CrNiMo 17-12-2 Gunmetal BS EN 1982 Cast Molybdenum Steel BS 3100 Bronze 88:10:2 Mix 2.22.2 Castings shall have an homogeneous structure and shall be free from defects, non-metallic inclusions or blowholes. All non-machined surfaces shall be carefully fettled and all foundry irregularities removed. Minor defects of a depth not exceeding 10% of the total metal thickness and that will not affect the strength or serviceability of the casting may be repaired using approved techniques. Larger defects must be reported to CPA and no repair made without approval. 2.22.3 All major stress bearing forgings shall be examined, including internally wherever possible, and be non-destructively tested for the detection of flaws. They shall be heat treated for the relief of residual stresses. 2.22.4 Dissimilar metals shall generally be isolated from each other. Where contact is unavoidable the metals shall be selected such that any galvanic corrosion shall not compromise the specified Asset Design Life. Machinery: General 2.23.1 Where practicable, machine assemblies shall be mounted on a common bedplate/baseframe complete with drive motor, gearbox, etc and be arranged for direct drive by use of flexible couplings. Where the design of the bedplate is such that pockets of air would be trapped during grouting, air vent holes shall be provided to allow air to escape 2.23.2 Where separate components/items of interconnected plant depend on correct alignment for satisfactory operation each item shall be positively located by machined spigot or by dowels or pins after alignment 2.23.3 Unless stated otherwise, bearings shall be selected and rated with an L10 (h) operating life not less than 40,000 hours at design duty conditions. Bearing assemblies shall be sealed-for-life to IP55W minimum. Oil-bath lubricated bearings shall be fitted with a pressure venting device, oil fill and drain tappings, and an oil-level sight glass. 2.23.4 Rotating elements shall be dynamically or statically balanced. Vibration levels shall not exceed values stated in the CONTRACT specific specification (where applicable) and shall be evaluated in accordance with BS 7854. Lateral critical speeds shall occur outside the range between ±20% of the rotational speed. Torsional critical speeds shall occur outside the range between ±10% of the rotational speed. 2.23.5 Couplings shall be selected to enable separation of the driver and driven components without the need to disturb the “other” component. Split-type couplings shall be supplied as a matched pair and shall be marked accordingly. Couplings shall be manufactured from forgings and shall be secured to their shafts by key and keyway. Spacer-type couplings shall be used where this would facilitate maintenance of either the driver or driven machine in-situ. 2.23.6 Belt drives shall be designed such that not more than 20% of the speed reduction is achieved by pulley ratios. All belt drives shall include a means of adjusting the tension of the belt(s). All multiple belt drives shall be provided with matched sets of belts. Lubricants 2.24.1 CONTRACTOR shall produce a complete plant lubrication schedule for approval by CPA. 2.24.2 Lubricants shall be matched to the "WA" identification system detailed in the North West Water document "Schedule of Lubricants by Suppliers". A copy of this document will be provided on request when CONTRACTOR is preparing his plant lubrication schedule. Where an item of plant requires the use of a lubricant not listed, CPA shall be provided with full details of the required lubricant. Lubrication Systems 2.25.1 Lubrication systems shall be sized to provide full protection of the plant throughout its designed operational envelope and environmental conditions for its intended lifespan. 2.25.2 Baseplate-mounted plant shall be designed, with drip trays or bunds provided as necessary, to prevent lubricants from leaking into process fluids or watercourses. Sealing systems shall be designed to prevent routine loss of lubricants into process fluids or watercourses. These measures are of particular importance for potable water treatment installations. Where lubricants may be ‘lost’ or leak into potable water (e.g. from a penstock actuator gearbox located over a potable water storage tank, or an air compressor charging a potable water surge vessel) then DWI approved lubricants shall be used. 2.25.3 All items of the lubrication system shall be located so as to be easily accessible from local floor level for routine lubrication and maintenance. Lubrication filling/charging points shall be located clear of moving machinery and shall be accessible without requiring the removal of guards, handrails or other safety devices. 2.25.4 Arrangements shall be made to prevent plant becoming overfilled with lubricant. 2.25.5 Grease nipples shall be button head type of a uniform size throughout the plant. 2.25.6 Oil sumps, reservoirs and tanks shall be fitted with fill plugs, drain plugs and sight glass level indicators. Dipsticks shall only be used if the provision of a sight glass is not possible. Sight glasses shall show normal, maximum and minimum oil levels, shall be enclosed in a protective metal case, and be readily dismantled for cleaning whilst the plant is in service. 2.25.7 Lubrication systems reliant upon pumped circulation of the lubricant and where failure of the system would result in catastrophic failure of the process plant or equipment, shall incorporate instrumentation to provide an alarm signal in the event of a blockage, loss of lubricant or other malfunction. 2.25.8 Prior to placing machinery into service all reservoirs, sumps and tanks shall be filled to their correct levels and all lubrication pipework shall be fully primed. Pumps : General 2.26.1 Pump impellers shall be manufactured from single castings and shall be positively located onto the pumpshaft and secured in a manner to prevent them working loose whilst rotating in either direction. 2.26.2 Where shaft sleeves are provided these shall be keyed or pinned to the shaft. Seals shall be incorporated to prevent leakage between the shaft and the sleeve 2.26.3 Pumps shall be fitted with cartridge-type mechanical seals. The seal manufacturer shall be consulted regarding the selection of the seal faces for a specific application. The pump casing shall be designed to collect and run to drain any seal leakages. Where necessary for satisfactory seal operation, provision shall be made for connection to a water supply for seal flushing. 2.26.4 Pump casings shall be subject to a hydrostatic pressure test prior to any coating or painting taking place. The hydrostatic test pressure shall be 1.5 times the casing design pressure, where the casing design pressure is taken as the ‘closed valve’ head generated by the maximum diameter impeller at the maximum running speed, plus the maximum suction head, all multiplied by 1.2. The test pressure shall be maintained for a period of at least 30 minutes without detectable loss of pressure or visible leakage 2.26.5 Acceptance Test : Centrifugal Pumps Unless stated otherwise in the CONTRACT specific specification, centrifugal pumps shall be tested at fixed speed in accordance with BS 5316: Part 1, (ISO 2548). The acceptance criteria shall be as follows applied to the guaranteed duty point value: At duty flow ± measuring instrument tolerances: Differential head : +5%, -2% Power absorbed : +4% Efficiency : -0.5% point NPSH (R) : +0% The pump shall be driven by its CONTRACT designated motor during the test. The motor shall have been tested to establish its load/efficiency characteristic prior to the pump test. Where variable speed testing is to be undertaken the designated inverter unit, motor and pump shall be ‘string’ tested to demonstrate the following: - Overall string efficiency at the guaranteed duty point with a zero negative tolerance on the quoted efficiency - Stable hydraulic and mechanical operation across the designated speed range - Maximum drive temperature at the designated top speed after stable conditions have been established for at least 30 minutes Fibre Reinforced Plastics (FRP) 2.27.1 Fibre Reinforced Plastic (FRP) products shall be manufactured from materials and by processes complying with the British Water Code of Practice BW: COP.22.96. 2.27.2 Orthophthalic Polyester must not be used on any wastewater application or in aggressive environments or for applications where frequent handling is likely. Protective Coatings to Metalwork 2.28.1 Protective coatings to all metalwork shall conform with the Water Industry Mechanical and Electrical WIMES Specification 4.01 “Protective Coatings for Use in the Water Industry” Issue 1, May 1996, with the following amendments; Table 1 - For both galvanised steel and hot-metal spray substrates, second coat, amend to read “Polyamide cured epoxy finish 100 micron” Total min. dft (including site applied coat) to be 165 micron. For mild steel, ductile and cast iron substrate, second coat, amend to read “Modified vinyl 100 micron”. Third coat, amend to read “Polyamide cured epoxy 100 micron” Table 2 – For both substrate options, first coat, replace “KF3B” with “primer” For both substrate options, 2nd coat, replace “KF3B” with “(chocolate)” For both substrate options, 3rd coat, replace “KF3B” with “(black)” 2.28.2 Galvanising of iron and steel articles shall conform to BS EN ISO 1461. Sheradizing shall conform to BS 4921 Class 1. 2.28.3 Stainless steel components shall be self colour. 2.28.4 This section does not cover the protection of buried pipework. Refer to Standard Specification, Section 2, Civil Engineering. 2.28.5 Protective coatings for proprietary items such as pumpsets, motors and gearboxes may be accepted in the manufacturer’s standard finish provided that the coating offered is equal to or exceeds the above requirements and meets with the approval of CPA. 2.28.6 Finish colours shall comply with Standard Specification M37 ‘Identification of Non-Buried Pipelines and Services’. Timber 2.29.1 The use of timber or timber structures for mechanical plant components is prohibited. Pressure Gauges 2.30.1 All pressure gauges shall comply with BS EN 837-1. Pressure gauges shall be Bourdon tube gauges unless agreed otherwise by CPA. 2.30.2 For wastewater and sludge applications, pressure gauges shall be independently mounted on a stub branch line not less than 50 mm NB for pipe sizes of 50mm and above. For pipe sizes below 50mm the stub branch shall be the same size as the pipe. All gauges shall be protected by a stainless steel seal diaphragm. An isolating valve shall be installed in each stub branch line on the pump side of the diaphragm. 2.30.3 All gauges shall have concentric dials of 100 mm (min.) diameter graduated in metres head. Under maximum head conditions the gauge pointer shall not exceed 90% of Full Scale Deflection (FSD). Ideally the guaranteed duty head shall be approximately 70% FSD. 2.30.4 Pump suction gauges shall be compound gauges calibrated to read both pressure and vacuum. 2.30.5 A test certificate for each gauge shall be issued to CPA, and a copy included in the relevant section of the Operating and Maintenance Manuals. 2.30.6 Pressure gauges shall be mounted in a position that is clearly visible from a walkway or access platform. Where practicable pressure gauges on an item of plant shall be mounted at the same height. 2.30.7 Where gauge connections are requested without the gauge being fitted, the connection shall be provided with a blanking flange or plug. INSTALLATION OF EQUIPMENT Setting of Machinery 3.1.1 All machinery shall be set in accordance with the manufacturers' instructions. 3.1.2 Machinery shall be set on flat steel packing pieces selected to take up any variations in the level of its foundation. The foundation shall be prepared to provide a suitable bedding for the packing pieces. One packing piece only shall be used at each holding down bolt location. 3.1.3 Machinery may be located on reinforced concrete plinths or foundation slabs : in these cases CONTRACTOR shall include for diamond drilling of holes for the holding-down bolts as necessary. 3.1.4 Final levelling shall be achieved using stainless steel or brass shims tailored to fit the contact area. Shim thickness shall not exceed 3mm and no more than 3 shims shall be used at each location. 3.1.5 Machinery shall be aligned, levelled and pulled down by tightening the nuts of the holding down bolts using a spanner of normal length. Grouting of holding down bolts where applicable, shall be carried out before the machinery is run. Final grouting-in of the machinery shall only be carried out after initial testing is complete and CPA's approval given. Pipework 3.2.1 Pipework shall be designed with independent supports and restraints to accommodate loads and thrust so as not to superimpose stresses onto machinery or plant items. Pumps, valves, meters, strainers and other such in-line equipment shall be supported independently of the pipework. 3.2.2 Flexible pipe couplings, flange adaptors or flanged fittings shall be incorporated into the pipework as appropriate to facilitate removal of plant items for maintenance, without the need to dismantle or disturb adjacent pipework / manifolds, and to allow for final closure of pipework joints without superimposing stresses onto plant items. 3.2.3 Where pipework passes through a wall, flanged joints shall be provided either side of the wall. 3.2.4 Where flange adaptors are used they shall be tied to the nearest flange, restraining structure, thrust block or wall. 3.2.5 Forged or formed bends shall be used for pipework used for the conveyance of wastewater. Fabricated bends shall only be used where standard fittings are unavailable and shall be long radius. Welded joints shall be dressed to a smooth finish both internally and externally. 3.2.6 Fabricated or lobster-back bends are acceptable for clean water installations. Fabricated bend radii shall comply with BS 534 Table 8 and shall comprise welding fittings to BS 1640. 3.2.7 Long radius bends shall be used on pipework conveying sludge. 3.2.8 Pipework conveying wastewater, chemical slurries, sludges, etc shall be provided with an agreed number of rodding points to facilitate clearance of blockages. 3.2.9 The pipework design shall include compensation for any thermal or other differential expansion by the incorporation of bellows, rocker pipes or similar approved devices. Pipework Supports 3.3.1 Pipework shall be supported in accordance with the manufacturer’s instructions or in accordance with BS 3974, parts 1, 2 or 3 as appropriate. 3.3.2 Pipe support brackets and clips shall generally be manufactured in mild steel, galvanised after fabrication. Plastic clips/brackets are acceptable for the support of thermoplastic pipework. Steel brackets in contact with thermoplastic pipework shall be free from sharp edges. 3.3.3 Each pipe support shall cradle the pipe over at least 180 degrees. Pipe Jointing 3.4.1 Pipe jointing surfaces and components shall be kept clean and free from extraneous matter until the joints have been made or assembled. 3.4.2 Where pipes with flexible joints are required to be laid to curves, the deflection at any joint as laid shall not exceed three-quarters of the maximum deflection recommended by the manufacturer. Welded Joints in Plastic Pipes 3.5.1 Fusion welded joints in high density and medium density polyethylene pipes shall be made only between pipes having the same physical characteristics. Joints between pipes from different manufacturers shall only be made with the specific approval of CPA. 3.5.2 Site fusion jointing shall be made in accordance with the North West Water document reference WSR 26/05 "Specification for Butt Fusion and Electrofusion Welding of MDPE and HDPE Pressure Pipes and Fittings". Sealing of Ducts 3.6.1 Ducts for cables and small pipes shall be sealed against the ingress of moisture and vermin once the cable or pipe installation is complete. Ducts shall be sealed to prevent the ingress of gas where one side of the duct is located in a zoned hazardous area or where a dangerous gas could be present. 3.6.2 Ducts must be sealed in such a way as to make it possible to break out the seal in the future without damaging the services within. Pressure Testing of Pipework 3.7.1 Completed pipework shall be hydrostatically pressure tested to 1.5 times; the maximum working pressure, closed-valve pressure (pumped systems), or peak surge pressure, whichever is the greater. The minimum duration for the test shall be one hour during which there shall be no loss of pressure and no visible leakage DESIGN Design Standards 4.1.1 Design shall be carried out to the requirements of the appropriate British or European Standard, or as specified in the CONTRACT specific specification. Full details of references, assumptions made and details of computer programs used for the design shall be submitted to CPA for review. Equipment Selection and Design 4.2.1 Mechanical plant and machinery shall be selected on the basis of achieving the closest possible match between the specified rated duty point and the optimum performance of the equipment. Typically a ± 20% variance may be accepted in this selection process. No potential operating point in the specified duty range shall lie outside the operating envelope of the machine. 4.2.2 The sizing and selection of equipment components shall be the responsibility of CONTRACTOR. Section sizes and service factors shall be based upon maintaining the integrity of the equipment over the entire operating envelope and for the Asset Design Life specified. 4.2.3 Sufficient information shall be submitted to demonstrate that equipment selection has been undertaken as described. For pump selections this shall include combined system and pump characteristic curves indicating for the various static head conditions, and for a range from zero flow to 130% of best efficiency flowrate, the following :- (i) pump output (l/s), normal and adjusted for station losses (ii) power absorbed curves (kW) (iii) pump efficiency curves (%) (iv) NPSH requirements (3% Head Drop) (v) selected duty points under solo and parallel running conditions (vi) the recommended limits of operation. 4.2.4 Where thin-walled stainless steel pipework systems are to be implemented in combination with either centrifugal or positive displacement machines (e.g. air compressor / blower systems), then CONTRACTOR shall design and demonstrate, by site testing, that the system does not pass through or approach within 20% of a system resonant frequency at any point within the specified / designed operational envelope. Noise output levels from such pipework shall comply with the requirements of clause 4.5 of this Specification. 4.2.5 Isolation valves for sludge and grit duties shall normally be knife gate type valves : resilient seal or eccentric plug type valves may also be used. Where isolation valves are actuated, or are required to be operated frequently, or are located above a working area, or the normal line working pressure exceeds 2.5 bar(g), then eccentric plug type valves shall be used Hazardous Areas 4.3.1 Where specified in the Design Statement, CONTRACTOR shall conduct a Potentially Explosive Atmosphere Zone check (PEAZ) in accordance with United Utilities’ ‘Code of Practice No 1, Installations in Potentially Explosive Atmospheres associated with Wastewater’ and BS EN 60079: part 10. Alternatively the Authority may undertake this work. In either case, Zonal Classification Drawings shall be produced indicating those areas identified by the PEAZ check process where the existence of potentially explosive atmospheres is considered possible. Equipment and process plant located within these areas shall be certified for use in a Zone 1 atmosphere. Electrical equipment shall conform to EN 50014 and shall be Eex certified by an appropriate EC certifying authority. 4.3.2 Where equipment or process plant is supplied which CONTRACTOR considers could affect the zonal classification of an area, he shall advise CPA accordingly. Hydraulic System Design 4.4.1 Pipework shall be designed using a roughness factor, ‘k’, appropriate for the pipe material in good, average and poor condition. The reference from which the ‘k’ values are taken shall be stated in the calculations submitted. 4.4.2 In the design of pumping systems, the pumpset manufacturer/supplier shall be consulted to ensure that the generated head for the pumpset is matched to the pipework/system configuration. 4.4.3 Pumping systems shall be designed to be self-priming wherever possible. 4.4.4 Pumping station pipework systems shall, unless stated otherwise in the CONTRACT specific specification, be designed for flow velocities generally as indicated in the following table: Flow Medium Velocities within Inlet Pipework (m/s) Velocities within Delivery Pipework (m/s) AverageMinimumMaximumAverageMinimumMaximum(a)(b)(c)(a)(b)(c)Clean water; Post grit settlement1.00.750.51.52.01.51.03.0Crude sewage; Sludge 1.3 1.2 1.5 2.0 1.2 2.4 Where: (a) – average design flow condition
(b) – preferred minimum
(c) – acceptable minimum if interchanged with velocities above 1m/s for several hours per day Where the pumping station is associated with a Primary or Humus sedimentation tank, then the maximum fluid velocity in the sludge draw-off pipework system shall not exceed 0.3 m/s. Where centrifugal pumpsets are to be used, the design of the pumpset inlet pipework system shall ensure that there is a positive head throughout the pipework system over the range of flows from zero to the rated flow, and for all sludge conditions in the specified operational envelope. All pumpset inlet pipework shall be as short and direct as practical. 4.4.5 Surge pressures shall be taken into account in the design of pressure pipework. Pressure pipework shall normally be designed to remain full while in service, inflow check valves shall be fitted where appropriate. 4.4.6 Air valves or air vents appropriate to the fluid in the pipeline and of adequate airflow capacity are required at high points. 4.4.7 Drain points shall be provided to allow the pipeline to be substantially emptied to appropriate discharge points. 4.4.8 Sludge pipework sections between isolating valves shall be fitted with a pressure relief device so that the isolated section will be protected against overpressure due to gas build-up. Self-closing devices shall be used in preference to bursting discs. The pressure relief device shall deliver the release to a visible but safe area. 4.4.9 Overflows shall be sized to pass the maximum possible flow, allowance must be made for parallel plant items being out of service. Overflows shall be designed to not operate until full utilisation of the plant is achieved. NB: The provisions of this clause do not apply to main drainage works. 4.4.10 Sufficient freeboard (recommended minimum 100mm) shall be provided to prevent overtopping of walls under all specified flow conditions and numbers of units in service. Allowance shall be made for dynamic effects, flow round bends and lateral inflow or outflow. Noise and vibration 4.5.1 Wherever possible, machinery shall be selected that has a noise output level less than 85 dB(A) at a distance of 1 metre from the centre line of the machine. Where this limit would be exceeded, noise attenuation measures shall be included to meet this requirement. 4.5.2 Machinery shall not be positioned such that the combined impact of existing and new machinery contravenes the Noise at Work Regulations. 4.5.3 Where noise levels exceed or are likely to exceed the First Level or the Peak Action Level, (as given in the Noise at Work Regulations), then a noise level assessment survey shall be carried out by a competent person. The survey report shall then be submitted to CPA for approval before the recommendations are implemented. 4.5.4 Vibration levels shall be assessed and tested in accordance with BS7854. Standard Specification Section - Mechanical Engineering Page PAGE ii Page PAGE 1of 21