Drainage and Underground Service Pipes

1.         PURPOSE

1.1       This fabrication and erection specification defines the minimum requirements for materials, workmanship, and testing for the supply and installation of underground drains and pressure pipes.

2.         scope

2.1       This specification applies to the construction of foul, surface, and contaminated water drains, manhole inspection chambers, and underground pressure pipelines designed by Air Products Europe (AP-E).

3.         related documents

3.1       Air Products Engineering Documents

            4ECE-M18                 Earthworks

            4WCE-670200           Fabrication and Erection of Process Piping

            4WPI-EW44001         Pressure Testing Of Process Piping and Equipment

            4WPI-SW70001         Standard Clean (Class SC) Inspection and Acceptance Requirements

            4WPI-SW70002         Process Clean (Class B) Inspection and Acceptance Requirements

            4WPI-SW70003         Oxygen Clean (Class AA) Inspection and Acceptance Requirements

            M10                           Concrete and Reinforcement

4.         CONSTRUCTION ON LAND NOT OWNED BY AIR PRODUCTS

4.1       Right of Way:  The Contractor shall set out the line of the service, remove any obstacles such as trees and hedges across the width of the easement. The Contractor shall also define the boundary of the easement.

4.2       Access on Right of Way:  The Contractor shall, at their own expense, erect any temporary access across dykes, water courses, and other areas within the width of the easement.

4.3       Additional Access:  When the Contractor requires additional access outside the width of the easement, the Contractor shall privately negotiate with the land owner, but must inform Air Products of any agreements reached.

4.4       Working Limits:  The Contractor shall keep all plant, material, labour, and excavated soil within the limits of the easements.

5. STORAGE AND HANDLING OF MATERIALS

5.1       Pipes, Valves, Fittings, and Manhole Fittings

5.1.1   All pipes and fittings shall be kept in a store or on a hard, clean surface. They shall be stored in groups according to type and size, and in such a manner that will prevent any damage or distortion.

5.1.2   All valves and similar items shall be stored indoors in suitable containers to prevent damage or contamination.

5.1.3   Pipes or fittings, supplied by the Contractor in a damaged or faulty condition, will not be accepted on site. Pipe bends shall be free of flat spots, corrugations, and cracks.

5.2       Jointing Materials, Compounds, and Joint Rings:  All joining materials, compounds, and joint rings shall be kept in a weatherproof dry store, in an orderly manner and protected from any petroleum or similar liquid.

5.3       Cement:  All cement on site shall be stored off the ground and protected from the weather. Cement shall not be kept in storage for longer than six weeks, and shall be used in rotation of delivery.

 

5.4       Aggregates:  Aggregates shall be stored on hard clean surfaces. They shall be kept free from dirt and any other deleterious matter. They shall be retained in separate compartments to maintain separate groups according to size. During cold weather the aggregates shall be kept as free as possible from snow and ice.

 

5.5       Reinforcement:  The reinforcement shall be kept in racks and shall be grouped according to size.

 

5.6       Brick:  Bricks shall be stored on a flat, hard surface and shall be grouped according to type. During cold weather, the bricks shall be covered with a tarpaulin or similar to prevent damage from frost. Only bricks that are sound in size, shape, and hardness shall be accepted on site.

 

5.7       Handling of Pipes and Fittings

 

5.7.1   Care shall be exercised in handling pipes and fittings in order to avoid distortion, flattening, denting, scarring, or other damage.

 

5.7.2   Pipes shall not be allowed to drop or strike objects which will damage the pipe, but shall be lifted or lowered from one level to another by suitable equipment. When lifting pipe is 200 mm in diameter or larger, special lifting hooks equipped with a plate curved to fit the curvature of the inside of the pipe shall be used.

 

5.7.3   In the case of the pipes having caps, equipment with curved plate or cap to fit the outside of the pipe shall be used. No punching of caps shall be permitted.

 

5.7.4   All materials damaged on the site shall be removed from the site and replaced with sound new materials by the Contractor at the earliest possible moment so that the scheduled progress of construction is not affected.

6. EXCAVATION

6.1       Excavation shall be to the line level and gradient of pipe and drain requirements shown on the drawings, and in accordance with 4ECE-M18. All trenches shall be wide enough to facilitate easy laying and inspection of the pipes.

6.2       The topsoil shall be stripped and stacked separately from the substrata. When soft spots occur, the soil shall be excavated to a firm base, then an approved backfill material shall be deposited and consolidated up to the correct level.

6.3       The bottom of the trench shall be finished by hand, well compacted to gradients when required by boning on to sight rails erected in convenient places. Bell holes shall be made at each joint to facilitate underhand work.

7. INSTALLATION – GENERAL

7.1       Metallic pressure piping installation shall be in accordance with 4WCE-670200. Other requirements in this specification are in addition to those detailed in 4WCE-670200.

8. LAYING, BEDDING AND SURROUND, AND PIPE WRAPPING

8.1       All Pipes:  Prior to installing any surround or backfilling, the Contractor shall give adequate written notice (which shall not be less than three working days) to the Engineer’s Representative to permit their inspection (which shall be additional to the Contractor’s inspection) of the pipe installation, corrosion protection, and proposed materials for surround and backfilling.

8.2       Flexible Pipes

8.2.1   Flexible pipes, such as plastic or pitch fibre and all pipes with flexible joints, are to be laid on hand compacted, approved granular bedding material.

8.2.2   The pipes shall be supported over the full length of the barrel, laid in straight lines and when applicable, with sockets up-hill, on a bed not less than 100 mm thick of the granular bedding.

8.2.3   The granular bedding shall be continued equally on each side of the pipe, for the full width of the trench. The pipe shall be surrounded with approved material compacted in layers not exceeding 100 mm thick in loose depth until the top of the pipe is covered by a thickness of at least 75 mm. After compaction, care being taken to ensure the pipe is not disturbed.

8.2.4   Before placing any granular fill, the annular gaps in flexible joints shall be sealed with puddles clay, or damp soil free from stones, or be otherwise protected from the intrusion of fill materials.

8.3       Rigid Pipes

8.3.1   Rigid drain pipes shall be laid on a bed of at least 100 mm thick of well compacted approved granular material with particle size not exceeding 20 mm (10 mm for 200 mm diameter pipes and below) laid true to gradient.

8.3.2   The sides and cover of the pipe shall be filled with similar approved material, hand compacted to provide at least 100 mm protection to the top and sides.

8.4       Field Drains

8.4.1   Porous concrete or clayware pipes shall be butt-ended without any jointing, on a well compacted and rammed rubble bottom 100 mm thick, laid true to gradients.

8.4.2   Hand compacted rubble shall be placed equally on each side of the pipe, for the full width of the trench, until the top of the pipe is covered by a thickness of at least 75 mm. Care shall be taken to ensure that none of the rubble enters the pipe to cause an obstruction.

8.5       Concrete Surround

8.5.1   When shown on drawings, pipes shall be laid on a minimum 100 mm thick bed of plain concrete, placed on the trench bottom which has been well consolidated and rammed by hand. The pipes shall be supported over the full length of the barrel, laid in straight lines and wherever applicable, with the sockets uphill.

8.5.2   The concrete shall have a minimum width of 300 mm, plus external diameter of pipe. The pipes shall be boned individually to maintain a constant gradient.

8.5.3   The sides and top of the pipe shall be surrounded with a minimum thickness of 150 mm of plain concrete, or to the details shown on the drawings, only after the testing of pipes has been successfully completed.

8.6       Steel Pipes

8.6.1   Puddle flanges shall be of 6 mm mild steel and shall be welded to the pipe so that the flange is central and perpendicular to the pipe.

8.6.2   When pipe is constructed into the wall of a pit or manhole, the wrapping shall be discontinued, so that the wall construction is built directly onto the untreated pipe barrel and puddle flange.

8.6.3   All flexible couplings shall be Viking Johnson Harnessed Couplings with lugs and connecting rods capable of withstanding the working and test pressures specified for the water service concerned.

8.6.4   Before installing the pipe within the trench, the pipe shall be inspected.

8.6.5   All loose rocks, stones, and other items which may damage any coating shall be removed from the bottom and sides of the trench before the pipe is lowered in.

8.6.6   Embedded rock or stone protruding from the bottom or sides of the trench shall be removed before lowering in.

8.6.7   When coated pipe is lowered in, care shall be exercised to prevent the pipe from swinging against or rubbing on the side of the trench.

8.6.8   Padded slings shall be used for handling coated sections.

8.6.9   Any damaged coating shall be removed and the affected area cleaned again. The pipe shall then be wrapped with a splice overlap onto the ends of the existing coating of at least 150 mm. This wrapping shall then be applied in accordance with the requirements for protecting steel pipes, including re-testing, as specified in Clause 8.8.

8.6.10 Backfilling at the trench bottom shall consist of a minimum of 150 mm of clean sand (2 mm maximum size).

8.6.11 After the coated pipe is lowered in, the pipe shall be surrounded and covered in such a manner to prevent any damage or abrasion of the protective coating. Care shall be taken to prevent shovels and tamping tools from cutting the coating.

8.6.12 The surround and cover shall be placed as soon as possible after the laying of the pipe. The surround and cover shall be clean sand with maximum size of 2 mm, and shall be well-compacted in layers with a maximum thickness of 200 mm, with at least 150 mm above the top of the pipe.

8.7       Non-Ferrous Metal Pipes:  Pipes shall be installed in accordance with Clause 8.6 except that pipes shall not be coated.

8.8       Protecting Steel Pipes

8.8.1   Steel pipes shall be coated with a proprietary wrapping as detailed below. If the Contractor wishes to substitute a factory applied coating, permission shall be sought from Air Products at least two weeks before the construction schedule requires application of the coating.

8.8.2   When factory coated pipe is used, the coating of the field-welded joint shall be performed with the same care as that is needed in coating pipe generally, with particular emphasis on the cleanliness of the pipe and the adjacent coating, and when required, the application of a suitable primer. The coating of the field welded joint shall then be coated with the proprietary wrapping detailed in Clause 8.8.6.

8.8.3   The pipe shall be cleaned before application. The pipe shall be free of all loose mill scale, dirt, rust, metal burrs, weld slag, sharp points, grease, oil moisture, or other foreign matter.

8.8.4   Pipes may be cleaned by wire brushing, solvents, shot-blasting, or pickling and phosphating. Primers shall be applied immediately after cleaning, and the primer shall be of the appropriate grade and quality of material to provide a good bond to the pipe. The primer shall be compatible with the coating material to be applied later as instructed by the coating supplier. The time interval between the application of the primer and the application of the coating shall be between the minimum and maximum intervals specified by the supplier.

 

8.8.5   The cleaned, dry pipe shall be brush primed with one thin continuous coat of quick drying Serviwrap Primer (supplied by Servicised Ltd), which must be allowed to dry completely.

 

8.8.6   The cleaned, dry and prepared surface shall be spirally wrapped with Serviwrap R15A (supplied by Servicised Ltd) with an overlap of 50% using sufficient tension to ensure conformability. End laps between adjoining rolls shall be a minimum of 150 mm. Moulding putty shall be applied to flanges, harnessed couplings, and valves to form a suitable profile for wrapping. The pipe shall then be wrapped with Serviwrap outerwrap (supplied by Servicised Ltd), with an overlap of 25 mm.

 

8.8.7   Servicised Products are available from:

 

                        Servicised Limited

                        Serviwrap Division

                        Ajex Avenue South

                        Berks

                        SL1  4BH

                        United Kingdom

                       

                        Telephone number:  01753 692929

 

8.8.8   If the Contractor proposes an alternative to Clauses 8.8.3 to 8.8.7, such proposals shall be made in writing (in English) to Air Products at least two weeks before the construction schedule requires application of the wrapping.

 

8.8.9   The coating or wrapping shall be tested by the use of a holiday detector immediately after the initial application and again before installation or backfilling. Normally, the holiday detector should be an electronic device providing a minimum test voltage of 10,000 to 12,000 V dc. or a creeping voltage of 20,000 V maximum. Any defects discovered during this testing shall be made good before the pipe is bedded and backfilled. The fact that coating repairs are made at this stage in no way lessens the need for careful handling of coated pipe.

 

 

8.8.10 When a pipeline is partly below and partly above ground, the coating used on the buried section shall extend 200 mm above the ground level. An additional coating may be necessary to protect the original from acidic degradation.

 

 

9. JOINTING

 

9.1       Rigid Joints

 

9.1.1   When spigot and socket joints are to be rigid, such as in concrete casing, the following

            jointing shall be made:

 

                 For clayware and concrete pipes, the joints shall be made by placing the spigot well into the socket of the pipe that had been previously laid down; caulking in tarred hemp to occupy one quarter of the socket depth, then filling the remainder of the socket with 1:1 cement mortar, well rammed in and finished off with a 45 degree fillet to form a bold collar around the pipes. The pipes shall be left thoroughly clean inside.

 

                 For cast or spun iron pipe, the spigot shall be centred in the socket by tightly caulking with tarred gasket or lead strip to half the depth of the socket. A jointed ring shall then be placed around the barrel and against the socket, and run with molten lead to fill the remainder of the socket.

 

                 Lead fibre may be used in place of run lead, whereon it must be placed in the socket, skein by skein, until the joint is full, making sure the fibre is well rammed as caulking proceeds. Alternative methods of jointing may be employed if approved by the Engineer.

 

9.2       Cutting:  When pipes are cut, they shall be cut by an approved method or by using a standard machine. The cut ends shall be squared-off true and be free from any roughness and projections. Material cast numbers shall not be removed by cutting.

 

 

10. CLEANING OF PIPES AND FITTINGS

 

10.1    Unless specified otherwise on the drawings, all pressure piping except fire mains shall be cleaned in accordance with the following Air Products Specifications:

 

            Specification                          Service

 

            4WPI-SW70001                        Utilities

            4WPI-SW70002                        Process lines except oxygen

            4WPI-SW70003                        Oxygen

 

10.2    All drainage pipework shall be flushed clean, to the Engineer’s approval, with water passing at a velocity of not less than 2 m/s. The discharge shall be at the lowest pipe level and shall continue until the pipework is clean and free and for not less than T seconds,

            where T = Length of pipe under test divided by 0.5 (metres).

 

10.3    Fire mains shall be free of excessive loose slag, mill scale, rust, grit, or other loose foreign substance (e.g., grease, hydrocarbons, jointing material).

 

10.4    After installation, all potable water lines shall be sterilized by specialists and flushed with mains water before use.

 

10.5    During construction, all cleaned material shall be maintained in its state of cleanliness until the completed system or installation has been accepted by the Engineer’s Representative.

 

 

10.6    Cleaned pipes shall be subject to inspection by the Engineer’s representative. The surfaces shall be examined visually under good lighting conditions to see that the pipe meets the previously prescribed conditions.

 

10.7    Any cleaned material that does not obtain approval from the Engineer’s Representative, or as a result of poor maintenance, reveals any deterioration from the standard of cleanliness required, shall be recleaned at the Contractor’s expense.

 

10.8    After cleaning, testing, inspection, and acceptance by the Engineer’s Representative, all terminations shall be sealed.

 

 

11. INSPECTION AND TESTING

 

11.1    General

 

11.1.1 The Contractor shall notify the appropriate Authority of their intention to test any water main or drain pipes, obtain all necessary approvals, and also inform the Engineer in writing.

 

11.1.2 Tests on drainage pipes must be completed before any backfilling or concrete surrounding is done.

 

11.1.3 When anchor blocks and tied couplings are required on pressure piping, these shall be installed prior to testing. Partial backfilling and leaving joints exposed are permissible with the agreement of the Engineer.

 

11.1.4 When a tracer is used, such as fluoride, the approval of Local Authority must be obtained and their instructions regarding disposal of test water shall be adhered to.

 

11.1.5 When work is being carried out in a catchment area, care shall be taken to comply with any special requirements laid down for work within the area.

 

11.1.6 All equipment, materials, and workmanship necessary for testing shall be supplied by the Contractor, and shall be subject to inspection and examination by the Engineer’s Representative at any place where fabrication and erection are carried out. Any defective materials and/or workmanship shall be corrected to the satisfaction of the Engineer.

 

11.2    Method of Testing

 

11.2.1 All drain lines shall be tested with water to a minimum head of 1500 mm (in a vertical tube of the pipe line under test) measured from the highest part of the invert of the pipes under test. At no point shall the head exceed 3000 mm of water.

 

11.2.2 Fifteen minutes or more shall be allowed for absorption, then the vertical tube shall be topped up and the water level observed for thirty minutes. If the level falls more than 25 mm per 30 metres of pipeline in this period, the cause shall be sought and the defect remedied.

 

11.2.3 All manholes and pits shall be tested for water tightness. The chamber shall be filled with water for 4 hours and the level of the water checked to see if any reduction in level takes place. There shall be no visible reduction in water level for approval to be obtained.

 

11.2.4 Pressure piping for fire, drinking, and circulating water shall be hydraulically tested at 1.5 times design pressure, in accordance with 4WPI-EW44001.

 

11.2.5 Other pressure piping shall be tested in accordance with the Project Pressure Test Procedure.

 

 

11.3    Test Results

 

11.3.1 An accurate log of all testing and three certified copies of the test certificates shall be delivered to the Engineer, upon completion of Contract. The test certificates shall be signed as correct by a competent inspecting authority, or by a person approved by the Engineer.

 

11.3.2 When the local authority or the Engineer refuse to give approval of any test, the Contractor shall establish the reason for refusal, and shall carry out suitable corrective measures for retesting until approval is obtained, all at the Contractor’s expense.

 

 

12. BACKFILLING

 

12.1    Prior to backfilling, the pipe shall be laid, bedded, jointed, protected, inspected, and tested, except that prior to testing, sufficient backfill shall be installed for stability.

 

12.2    The trench above the pipe surround (see Clause 8.6.12) shall be filled with selected excavated material and hand punned in layers 200 mm thick, maximum particle size 50 mm, to a minimum of 1000 mm above the pipe; thereafter punning with a light mechanical punner maximum particle size 200 mm up to a subsurface level. When applicable, the topsoil shall then be replaced, tilled and raked. Suitable material for backfilling shall be as defined in 4ECE-M18.

 

12.3    When a drain or pipe has been laid under a trunk or main road, backfilling and protection of pipe shall be as shown on drawings.

 

12.4    Backfill above rubble surrounds to porous field drains, shall consist of further selected rubble, particle size between 40 mm and 20 mm, and be free from dust, laid to the underside of the topsoil. When applicable, the topsoil shall then be replaced and tilled as necessary.

 

12.5    Backfilling around manholes and pits shall be of selected excavated materials, containing no particles greater than 200 mm in size. The fill shall be deposited in 300 mm thick layers and compacted to a degree of compaction similar to that of the adjacent substrata.

 

12.6    If required, the Contractor shall provide supports at above ground termination points of pipe, to prevent movement of the pipe during backfilling. The supports shall be capable of being removed as backfilling progresses.

 

 

13. FUTURE CONNECTIONS FOR DRAINS AND PRESSURE PIPES

 

13.1    End plugs or plates shall be provided to drains or pressure pipes when connection for future extensions are provided.

 

13.2    When the drain or pipe is commissioned or tested before the future connection is made, full strength plugs or plates must be provided to resist the pressure or flow in the line.

 

13.3    Elsewhere, covers shall be provided to keep drains and pipelines clear of foreign matter.

 

13.4    All above ground termination points shall be accurately set out to line and level. Setting out points shall be established such that the locations can be checked during and after backfilling.

 

13.5    When flanges are required at termination points, they shall be set out truly horizontally, or vertically, as indicated on the drawings.

 

13.6    Other requirements for pressure piping terminations are as follows:

 

 

13.6.1 All pressure piping terminations shall be installed to within the following tolerances when measured from setting out points:

 

                 3 mm for 10 inch nominal bore and below.

                 5 mm for 12 inch nominal bore and above.

                 Flanges shall not be out of square by more than 1:250 of outside diameter of flange. Angular tolerances shall be plus or minus 0.5 degree.

 

13.6.2 Improperly fitted piping and out of tolerance shall be removed and replaced as directed by the Engineer’s Representative at the Contractor’s expense.

 

13.6.3 Unless specified otherwise, flange terminations shall be flat faced, weld necked with bolt holes orientated on the plant grid.

 

13.6.4 Gaskets and blind flanges shall be supplied and installed on terminations to facilitate testing and ensure cleanliness of pipes. The gaskets and blind flanges shall remain in position for removal by others.

 

 

14. CONNECTION TO EXISTING DRAINS AND SEWERS

 

14.1    The breaking into an existing sewer owned by the Local Authority should be done by the Local Authority or under their supervision. Connection to existing water mains should be carried out by the pipe owners or under their supervision. The Contractor is responsible for contacting the Local Authority or owner and arranging for the connection to be made. Every precaution must be taken to ensure that broken material does not enter the pipes.

 

14.2    Projections or any other obstruction that would cause reduction in area of the pipes must be avoided.

 

14.3    When possible, in clayware piping, saddles shall be used for supporting the connection pieces.

 

14.4    The Contractor shall check the invert of existing drains and ditches before laying new drains, and shall notify the Engineer immediately if the declared invert levels are found to be inaccurate.

 

 

15. MAINTENANCE OF EXISTING WORK

 

15.1    The Contractor shall ensure that a full flow is maintained in existing underground services for the duration of the works.

 

15.2    Buried Services:  All pipes, ducts, cables, mains, and other services exposed by the excavations shall be effectively supported by timber, slings and chains, or other approved means. The size and position of every service shall be carefully measured, and a sketch submitted to the Engineer for record purposes. Any damages to existing services shall be reported immediately to the Engineer.

 

 

16. CONNECTION TO EXISTING LIVE CARBON STEEL PIPES

 

16.1    Connection to existing live carbon steel water lines shall be undertaken by specialists approved by Air Products as having had suitable experience of such work.

 

16.2    All flanges shall be flat faced and valves shall be cast iron bronze trim gate valves.