tender specification sewer

8/22/2019 Tender Specification Sewer

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SPECIFICATIONS FOR UNDERGROUND GLASSFIBER REINFORCEDPLASTIC (GRP) PIPES & FITTINGS FOR SEWER

1. Scope

This specification applies to the furnishing of all labor, materials and services in connection with themanufacture, testing, delivery, installation and commissioning of underground glass fiber reinforcedpiping, fittings and specials as specified in the engineering documents and drawings.

2. Codes and Standards

All pipes, joints and fittings supplied under this specification shall, as a minimum, meet the requirements

of AWWA C950. Other standards as applicable may be used.

IS 12709 : 94 IS standard for GRP pipes for potable water application

IS 14402 : 96 IS standard for GRP pipes for applications other than potable water

IS 13916 : 94 IS standard for laying of GRP piping system

ASTM D3517 Standard Specification for Fiberglass (Glass Fiber Reinforced Thermosetting Resin)Pressure Pipe in the case of pressure pipes

ASTM D3262 Standard Specification for Fiberglass (Glass-Fiber Reinforced Thermosetting Resin)

Sewer Pipe, in the case of gravity sewer pipes.

ASTM D3754 Standard Specification for Fiberglass (Glass Fiber Reinforced Thermosetting Resin)Sewer and Industrial Pressure Pipe.

ASTM D4161 Standard Specification for Fiberglass (Glass Fiber Reinforced Thermosetting Resin)Pipe Joints Using Flexible Elastomeric Seals.

3. Qualification criteria & Product Description

The manufacturer should have manufactured GRP pipes using Continuous Filament Windingprocess adopting Continuous Advancing Mandrel method for large diameter pipe DN600 andabove and below DN600 helical winding process may be adopted.

It is mandatory for the EPC contractor to accept and make agree GRP pipe manufacturer /supplier, to commit an agreement of maintenance of sewer pipeline for 5 years after the expiryof warranty period, and that the pipes, joints, bends etc. and chemicals, will be made availableduring the above contract period and any defect will be rectified within a period of 48 (fortyeight) hours from the time of reporting the defect.

Also, the scope of work includes the supervision of installation and commissioning of pipeline byGRP pipe manufacturer and training of Owners O & M personnel to jointing of pipes,replacement of gaskets, installation of pipes and complete maintenance aspects of GRP

pipelines.


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3.1 Materials

3.1.1 Resin Systems

The manufacturer will use high elongation (5-6%) isophthalic polyester in liner andisophthalic polyester (3-5% elongation) in structure of the pipe as iso resin is suitable toresist chemical attack by Sulphuric acid which is the main constituent of any sewer water.

3.1.2 Glass Reinforcements

The reinforcing glass fibers used in the manufacture of the components shall be of highestquality commercial grade E glass filaments suitably treated with binder and sizingcompatible with impregnating resins.

3.1.3 Fillers/Aggregates

Silica sand or other suitable materials (size range between 0.05 mm to 0.5 mm) may beused as fillers/aggregates in the laminates.

3.1.4 Elastomeric Sealing Rings

Elastomeric Sealing rings must be supplied by recognized, acceptable qualitymanufacturers. The EPDM elastomeric compound used must be compatible with the enduse environment. The elastomeric seals shall confirm to the provisions of IS 5382.

3.2 Manufacture and Construction

3.2.1 Pipes

The pipes shall be supplied in accordance with the diameters and tolerances specified insection 3.3. Large diameter pipe (600 and above) will be manufactured by a controlledreproducible continuous advancing mandrel process using the materials described in

Section 3.1 to result in a corrosion resistant, composite structure to meet the operatingconditions for this project. Structure of pipe must content chemical resistance liner andreinforced structural layer. Liner should be at least 1.5 mm thickness, made of surface veil,chop glass and chemical resistance resin at the resin to glass ratio 80:20. Out of 1.5 mm0.6 mm inner layer must built with surface veil and resin. Rest 0.9 mm thickness will bebuilt with chop glass and resin. Reinforced structural layer must follow I-beam principle.Sand layer can be incorporated in the centre of the reinforced structural layer and would besandwiched by two glass rich skin layers. To avoid any delamination sand layer mustcontent at least 6 - 8% glass reinforcement. Pipe shall have to be provided with UVstabilized resin coat as external layer for above ground application. Pipe diameter less than600 mm may be produced in helical winding process. But the reinforced structural wallmust follow the I-beam principle as below.


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3.2.2 Joints

The large diameter(DN600 and above) pipe shall be field connected with GRP sleevecoupling that utilizes EPDM elastomeric Sealing rings to maintain joint water tightness.Below DN 600 pipe may be jointed with double O ring bell and spigot joint.

Depending on site condition butt and wrap joint is also permissible to some extent.

Flanged joints shall be used for connecting GRP pipes with valves and other type of pipes.Flanged joints shall be used with EPDM gasket and hot dip galvanized bolts as per IS: 1367

3.2.3 Fittings

Flanges bends, reducers tees wyes and other fittings shall, when installed be capable ofwithstanding all operating conditions. They may be contact molded or manufactured frommitered sections of pipe joined by glass fiber reinforced polyester overlays.

3.3 Dimensions

3.3.1 Nominal Diameters

Pipes will be supplied with the following nominal diameters in accordance as specified inAWWA C950/ IS 12709 & IS 14402.

3.3.2 Lengths

The pipe standard effective length will be 6,9,12 meters with a tolerance of 25mm. Amaximum of 15% of the pipe sections maybe supplied in random lengths subject to theapproval of the engineer.

3.3.3 Wall Thickness

The wall thickness shall satisfy the inside and outside diameters specified in IS: 12709. The


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wall thickness and outside diameter shall be measured to an accuracy of 0.1 mm

3.3.4 End Squareness

All pipe ends shall be square to the pipe axis 6mm or 0.5% of the nominal diameterwhichever is the greater.

3.3.5 Tolerance of Fittings

The tolerance of the angle of a bend and the angle between the main and leg of a wye ortee shall be 2 . The tolerance on the laying length of a fitting shall be + 50mm.

4. Product Selection

4.1 Stiffness

Stiffness selection is dependent on burial conditions and operating vacuum (if it exists). Minimumstiffness requirements must be determined for both parameters and the higher of the two mustbe the minimum selected for Pipes which shall be supplied. The minimum initial ring stiffness forwithstanding above load conditions and in addition AA class live load with maximum of 5% of longterm ring deflection shall be appropriately determined. However, recommendation for stiffnessclass in general would be as below

DN 200-500 496 kPa (10000 N/m2)

DN 600-1800 248 kPa (5000 N/m2)

DN 2000-3000 124/248 kPa (2500/5000 N/m2)

4.2 Pressure Classes

Pressure classes of the pipe can be selected based on working pressure, surge pressure andfriction head.

5. Qualification Testing

The physical properties and characteristics of the pipes shall be determined by prototype testing of themanufactured product. These tests need not be conducted specifically for this Project if prior tests onsimilar products have been previously completed. Testing may be conducted on one diameter andextrapolated to other diameters, the pipes are of similar composition and material arrangement and aremanufactured from the same materials specification using a similar process.

5.1 Hydrostatic Design Basis HDB

The Hydrostatic Design Basis (HDB) will be obtained in accordance with IS 12709/IS 14402B orASTM D2992 established at an extrapolated 5O year value.


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5.2 Long Term Strain corrosion

The long term strain corrosion test shall be in accordance with AWWA C950 for water Projects orASTM D3262 Section 6.3 for sanitary sewer projects.

6. Inspection and Testing

The GRP pipes supplied by the contractor/manufacturer will be subjected to following tests as perAWWA C950 / IS 12709/14402 for acceptance :

6.1 Workmanship

Pipes shall be free from all defect including indentations, de-Lamination, bubbles, pinholes,cracks, pits, blisters, foreign inclusions and resin starved areas. The pipe shall be a uniform ascommercially practicable in color opacity, density and other physical properties as per ASTM2563/BS 5480/ IS 12709/ IS 14402. Internally maximum 3% area and externally maximum 15%area can be reworked.

6.2 Hydrostatic Pressure Test

Each length of irrespective of diameter shall be tested for Hydrostatic test as per IS 12709 atManufacturers premises before dispatch

6.3 Longitudinal Tensile Strength

One in each batch of pipe shall be tested for longitudinal tensile strength as per AWWAC950/IS12709/14402.

6.4 Hoop Tensile Strength

One in each batch of pipe shall be tested for hoop tensile strength as per AWWAC950/IS12709/14402.

6.5 Stiffness test

One in each batch of pipe shall be tested for stiffness as per AWWA C950/IS12709/14402.

Any other tests required as per the provisions to which the supplied pipe confirms i.e. (AWWAC950/IS12709/14402)

The test reports for the rubber gaskets shall be as per acceptance test of the IS 5382

The sampling method for testing shall be as per the provisions of the standards to which they aremanufactured.


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7. LAYING AND JOINTING OF PIPE LINE

7.1 General

Where ever there is need for deviation, it should be done with the use of necessary specials or bydeflection in pipe joints (limited to 5% of permissible deflection as per relevant standards).

7.2 Stadards

Except otherwise specified in this technical specification, the Indian Standards and Codes of Practice intheir latest version, National Building code, PWD specification shall be adhered to for the supply,handling, laying, installation, and site testing of all material and works. The laying pipeline shall be doneconforming to the following standards : IS : 13916 for GRP pipeline.

7.3. METHOD OF UNDERGROUND INSTALLATION

7.3.1 SOIL -PIPE SYSTEM

The external loads (soil and traffic) above a GRP buried pipe cause a decrease in the vertical diameter

and an increase in the horizontal diameter (deflection), that is indicative of strain (stress) levels in the

pipe wall.

The horizontal movement develops a passive soil resistance that enhances pipe support.

The amount of deflection depends on soil load, live load, native soil characteristics, pipe backfill material,

trench width, haunching and pipe stiffness.

Buried fiberglass pipes generally accommodate 4-5% long term deformation without structural damage.

Proper selection of pipe stiffness class and corresponding installation type helps to maintain pipe

deflection within acceptable levels.


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7.3.2 CLASSIFICATION OF NATIVE SOILS

Native soils according to AWWA 950/95 are classified in 4 soil stiffness category. The soil groups depend

both on soil types (classification) and soil density, which together determine the soil modulus. The

symbols GW, GP, SW, SP, GM, GC, SM, SC, ML, CL etc.. are in accordance to ASTM - D2488.Soil stiffness category 1 (SC1)

Crushed rock and gravel with


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-Stable trench walls or rock trench

Trench wall usually can be made vertical from the bed to the top of the pipe without the use of shoring

or sheet piling.

-Unstable trench walls and bottom

The trench will be excavated with vertical wall providing sheet shoring, installation method 1or with the

natural slope of the soil, installation method 2.

The foundation shown is required when the trench bottom is unstable, i.e. made up of soils whose

displacement, due to variation in stress or moisture content, is very high. Depending on the conditions

of the unstable trench bottom, the installation contractor may require different types of foundations

such as :

-Stabilization of the bottom material, by removing it for a minimum depth of 200 mm

and replacing it with stabilized gravel or sand, into which the unstable soil will

not penetrate (ground capacity from 0.7 to 0.9 kg/cm2); -Concrete material with

a minimum depth of 150 mm (ground capacity from 0.5 to 0.7 kg/cm2); -Piles

capped by a concrete material (ground capacity from 0.5 to 0.7 kg/cm2). The

above instruction must be as strictly followed as larger is the pipe diameter.

Installation method 1


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assure firm support in this zone

Installation method 2-Granular soil trench

The trench walls shall be at the natural slope of the native granular material. Pipe shall be installed as

shown in the figure relative to unstable trench, installation method 2.

-Soft soil trench

When the native is composed by highly plastic substances, very compressible, with a water content

percentage on the dry soil weight exceeding 50%, as soft clays, very melted mud, etc., the granular soilused for the laying bed and the backfilling can be absorbed by the native soil. In this case, it is suitable

to cover the bed and the walls with a fabric non-fabric (geotextile), which has the function of separating

the layers to prevent that the materials composing the bed and the backfilling from being mixed or

buried.

-Trench width

The trench width shall be such as to guarantee the minimum distance pipe/trench wall allowing

backfilling compaction, according to the type of material used and the compacting method. Furthermore,

in case of installation of soils not able to grant the side support requested by the project, the trench will

be widened, according to the designers prescriptions, in order to stabilize the soil.

Suggested value for the trench width is as follows:

L= DN + 400mm

L= DN + 600mm

L= DN + 800mm


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The depth of the trench must be such as to have the bedding of the dimensions foreseen in the next

paragraphs. If the soil is not able to give the vertical support requested by the project, the trench will be

deepened of 20cm or more, according to the prescriptions given by the designer, in order to obtain a

more stabilized soil.

Moreover, should butt and strap joints be executed within the trench, it must be widened by 2 meters

for a length of two meters in the joining area, in order to allow proper operations.

At the above locations the trench bottom shall be adequately lowered. These joint housings will be filled

during backfilling

-Trench excavation below water table

Where an unstable soil condition is encountered which is caused by water table, the bottom of the

trench must be stabilized before laying the pipes.

This can usually be accomplished by lowering the water table about 30 cm below grade pipe by means

of pumps and stabilizing the bottom as already described.

To minimize the dewatering, only enough trench should be opened to place one or two lengths of pipe

and then backfill.

-Bedding

The bedding shall be minimum 150 mm thick and shall provide the pipe with an uniform and continuous

support over its entire length.The bedding surface shall be even and recesses shall be left corresponding to pipe joints. These

receptances shall be backfilled after pipe installation and joining.

We recommends the use of pea gravel, or crushed stone or sand as bedding material, with a fine

content not exceeding 12%. With fines we mean materials passing through the ASTM 200 sieve. The

maximum dimensions of the bed materials diameter should not be greater than 20mm.

The bed must be compacted until reaching 70% of its maximum density, before the pipe installation

(90% Proctor Standard).

-Backfilling

Backfilling material will be the same as used for bedding (maximum lime content 10% and maximum

particle size 18 mm).

Backfilling is ideally divided in two areas : primary backfilling which vertically extends from the lower

generatrix of the pipe as far as 70% of the diameter and secondary backfilling, extending as far as 15

cm above the upper generatrix of the pipe.

Backfilling shall be placed in singly compacted layers 200-250 mm high up to 70% of pipe diameter and

300 mm high up to the top.

Backfilling up to the ground level with native material has to be completed.


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Compaction can be made by using an impulsive compactor or any other suitable equipment.

Please address the Technical Office for prescriptions relevant to the compaction ratio and the depth of

the bed.

7.3.4 PIPES INSTALLATION

To install the pipes, the following procedure can be used, in accordance with the type of joint and the

pipe diameter:

a) for any type of joint and diameters: lay and align the pipe bars on the previously prepared bed, and

perform junctions inside the trench.

b) for pipes which joints guarantee the axial continuity:

-lay on the bed two or three bars, previously joined outside the trench, so as to reduce the

number of junctions to be performed inside the trench.

-align and join the pipe bars by the side of the trench or above it, using ties; let the already joined

pipeline down the trench, using more hoisting equipment and taking care not to cause

excessive

deformations; this method can be used for small diameters only.

In case of bell/spigot or socket joints with o-rings, please verify that angles exceeding those allowed

have not been given.

7.3.5 TYPICAL COMPACTION METHODS

The following compacting suggestions will enable to achieve the maximum practical material density.

Excessive compaction or compaction with inappropriate equipment can result in pipe deformation orpipe lifting off the bedding. Care must be used when compacting the pipe zone backfill with frequent

checks of pipe shape.

Coarse grained soils - 5% fines. For coarse grained soils with less than 5% fines, the maximum

density results from compacting, saturation and vibration. Further to the use of internal vibrators,

heights of successive lifts of backfill must be limited to the penetrating depth of the vibrator. The backfill

is placed in lifts of 0.15 to 0.3 m. Pipeline flotation has to be avoided when saturating the pipe zone

backfill area. Water jetting will erode side support and few experts recommend it. Placing backfill over

the pipe must be avoided, while the pipe zone material is saturated. That would load the pipe before the

proper support can develop.

Coarse grained soils - 5 - 12% fines. Compacting of coarse grained soils containing between 5 and

12% fines, is carried out such as by tamping or saturation and vibration. The method used should result

in the maximum density of the backfill.

Coarse grained soils - > 12% fines. Coarse grained soils containing more than 12% fines, compact

best by mechanical tamping in lifts of 0.1 to 0.15 m. In particular for fined grained soils, the soil

modulus (passive soil resistance) is density sensitive and a greater compact effort will be required to

obtain the necessary Proctor density dictated by design.

Compaction and Installation. Quality Control


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Deflection checks must be carried out when the first installed pipes are backfilled to grade. Further

periodical checks must be done throughout the entire project. Where practical, measurement has to be

taken of the in-place density of the compacted primary pipe zone material to ensure compliance with the

design assumptions.

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