Sep Cross Country Piping

DEVELOPMENT CONSULTANTS LIMITED

STANDARD ENGINEERING PROCEDURE # 01201-SEP-M-133

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STN GRP SL CLASS Sg1 Sg2 Sg3 RIAS CAT #

SEP NONE NONE NONE

DOC #

01201-SEP-M-133 E-MEDIA ARCHIVED

TITLE

Design and Optimization of Cross-Country Water Piping

AUTHOR

Technology Control Cell, Mechanical

ABSTRACT This document discusses various activities towards finalization of major parameters of cross-country water piping and aims to indicate the procedure for optimizing the system.

KEYWORDS 1

MS Pipe 2 Optimization

3

DI Pipe 4 FRP Pipe

5

6

2 1 0 FIRST ISSUE REV # STATUS REV. DESCRIPTION

ENDORSEMENTS 2 1 0 30.08.12 Sanchari

Paul DSM DSM

Initial Signature Initial Signature Initial Signature REV # DATE PREPARED REVIEWED APPROVED

This document contains proprietary information of Development Consultants Limited and is to be returned upon request. The contents may not be copied, disclosed to third parties, or used for other than the express purpose for which it has been provided, without the written consent of Development Consultants Limited.



TITLE : DESIGN AND OPTIMIZATION OF CROSS-COUNTRY WATER PIPING

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1.0.0 INTRODUCTION

Cross-country pipeline is primarily a transmission line for transporting bulk quantity of fluids over large distances. The transmission distance may be a few kilometers, or even hundreds of kilometers. For example, in India, cross-country pipeline for LPG transportation from Jamnagar, in Gujrat, to Loni, in Pubjab, covers a distance of about 1300 km, whereas, the HBJ pipeline covers a distance of almost 2300 km.

Cross-country pipeline has also been extensively used for transport of water, as, often, water source is not available in close vicinity to consumer point. Such pipeline may run thru land, rivers, marshy areas, roads, forests etc.

This Standard Engineering Practice discusses the various activities towards finalization of major parameters of a cross-country water piping system and aims to indicate procedures for optimizing the cross-country piping system related to material of construction of pipe, thickness, corrosion protection and laying of pipe.

2.0.0 PRE-PROJECT ACTIVITIES

The pre-project activities during preparation of feasibility report and TEFR should have already identified the source of water for meeting the requirement of the proposed plant. For such identification, the Project Authority needs to discuss with irrigation dept. to ensure the availability of required quantity of water, the seasonal fluctuation, if any, examining recommendations, such as, constructing weir to enhance assurance of available water etc.

During execution of cross-country water project, the initial activities that the Project Authority needs to be advised is to appoint a bathymetric surveyor, who will interact with irrigation department to re-examine availability of water. The bathymetric surveyor will also identify the configuration of intake system whether on-shore or off-shore, location of intake well / intake pump house and low water level / high water level of the intake structure which will be subsequently utilized for preparing the GA dwg. of intake well / intake pump house.




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On reassurance of water availability, the Project Authority also needs to examine the seasonal fluctuation, if any, and the mitigating measures such as making a raw water reservoir at plant site, to ensure availability of required quantity of water for the plant, even when supply from source (river or lake) has reduced or altogether stopped.

The next step that the Project Authority needs to be advised is to appoint a surveyor for conducting the route survey. There can be many alternatives for routing the pipeline from supply point to consumer point. It is necessary to work out techno-economic comparisons of various routes taking care of the route length, the nature of obstacles along the route etc. Ideally, the pipe should run close to existing roads so that the erection and maintenance activities can be carried out conveniently.

Once the route from supply to consumer point has been identified, the route survey is intended to further furnish data such as :

a) Spot-level survey at every 50 to 100 metres & at least over 10 m on either side of the probable route.

b) Soil conditions in the form of bore-logs, trial pits, chemical tests on subsoil & ground water etc.

c) Alignment map with lengths, bearings, angles etc. to know the exact route & the total length of the pipe-line.

d) Details of the route and their locating dimensions with respect to sea, roads (crossing and along the route) rivers, nallas, pipe-lines, bridges, rail-tracks, transmission lines, underground services including cables/ pipes etc., hills and mountains, buildings, plantation, forests, agricultural land etc.

e) Cadestral Survey The route may be passing thru so many lands belonging to private owners, farmers, govt. authorities, defence wings etc. En-route information and data has to be collected for such land pieces. Such data will include :

- Type of land and the owners name - Length of the route thru the land - Problems in acquiring Right of Way (R.O.W.) - Authority which will permit/grant ROW. - Survey maps for the land available from the local Land Authority

(such as Collector, Tahasildar, Gram-Panchayat etc.) - Land records regarding the title and ownership of the land - Approx. compensation required for acquiring the R.O.W.




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- Status of Habitation on the land - Similar information of the adjacent plots on 50 to 100 m on either

side of the route - Plans for future installations by others on the proposed route and/or

in the vicinity such as roads/rail-tracks/buildings/pipe-lines etc.

f) Availability of construction materials, labour & facilities.

[Since the pipe-line has to pass thru different areas and over a long distance, it is essential to know the availability of construction Labour and Materials on the way such as excavation labour, transport facilities, access roads, construction material like stones, aggregrates, sand, cement, steel structurals, workshop facilities etc. This information will be useful in working out the project schedule and cost estimates and assessing the problems during construction.]

g) Soil Resistivity Survey required for design of cathodic protection system.

h) Names and addresses of the statutory and public bodies required to be contacted for acquiring ROW, construction permission, blasting licenses, interfering with the public facilities (Roads, rivers, rail-tracks etc.) and cathodic protection work, power supply/water supply etc.

[Such authorities include the following but not limited to the listed ones.

Local land authorities Distr. Collector, Municipal Corporation, Tahsildar, Owners of the respective land.

P.W.D. Authorities Local Office Irrigation Department Electricity Supply Agencies / Bodies / Boards Water-supply and Public Health Department Controller of Explosive and use of Hazardous Chemicals Industrial Development Corporations Railway Authority Marine and Port Authority Salt-commissioner and Controller Competent Authorities for Land and ROW acquisition State and Central Govt. for necessary permission, licenses,

clearances etc. Import/Export rules / regulations authorities Controller of Quarrying and Mining Navy/Army/Air force (Defence Authorities) Plants for future installations MOEF ]




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3.0.0 PROJECT ACTIVITIES

Based on various data collected as in 2.0.0 and the cost estimates, over all project schedule has to be prepared based on past experience, and specific problems unique to the project under consideration. This schedule should cover only broad activities to serve as a guide line for preparation of detail activity schedule.

This should generally include :

a) Preliminary survey / data collection. b) Finalising the route c) Cost estimates / budget sanctions. d) Acquisition of R.O.W. and land e) Basic engineering package f) Detail engineering work g) Construction work (Civil/Mech./Piping/Elect., Marine Crossing, River

Crossing etc. / Cathodic Protection). h) Testing / Flushing / Pigging i) Commissioning and hand over

This will establish the overall completion time for the entire project work.

4.0.0 BASIC ENGINEERING

Once the route survey and bathymetric survey document is available, the Basic Engineering can be started.

The first step required for Basic Engineering is to finalize the pipe parameters with regard to MOC, diameter, thickness (or class), corrosion protection and laying requirements. The life cycle cost of various alternatives will be compared to arrive at the final selection. The basic guideline for calculating these parameters are furnished in the subsequent clauses.

5.0.0 MATERIAL OF CONSTRUCTION

Popularly used Material of Construction for cross-country pipe line used to be MS. Generally, spirally welded factory made SAW type MS pipes are preferred. The methodology of manufacture of such pipe ensures better quality of welding with in-built 100% radiographic testing facility. Such improvement in quality of pipes is achieved at a very normal incremental cost and, hence, should be recommended.




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Ductile Iron pipes has been another popular MOC for cross-country water pipes. Invented in 1949, it retains the corrosion resistance of Cast Iron, but has more than double the tensile strength of cast iron and even more than MS. Impact resistance, also, is quite high and comparable with MS pipe.

Fiberglass pipe, commonly called as FRP or GRP pipes, made from glass fiber reinforcements embedded in , or surrounded by thermosetting resin is also becoming popular as pipe material for water transportation. A few years back, GRP pipes used to be costly and, hence, application of GRP pipes used to be considered only as corrosion-resistant alternative to protect steel, stainless steel or other exotic materials. However, presently, large scale bulk use of GRP pipes have attracted many manufacturers producing GRP pipes. This, coupled with rapid improvement in manufacturing technique, has brought down the prices of GRP pipes and has become highly competitive with MS or DI pipes.

A brief comparison of pipes with above 3 material of construction is indicated below :

MILD STEEL PIPE vs. DUCTILE IRON PIPE vs. FRP PIPE

Sl. No. Criteria

Mild Steel pipeline

Ductile Iron pipeline

Fiberglass Reinforced

pipeline

1 Friction loss C* = 120 Hence, friction loss is maximum

C = 140 Hence, friction loss is less than MS but more than FRP

C = 150 Hence, friction loss is least

2 Total energy cost Maximum, since friction loss is maximum

Less than MS. More than FRP Least

3 Corrosion resistance

Susceptible to corrosion. Hence, inner and outer lining is required

More Corrosion resistant compared to MS.However,, inner lining and external painting is required.

Highly resistive to corrosion. Hence, no lining is required




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Sl. No. Criteria

Mild Steel pipeline

Ductile Iron pipeline

Fiberglass Reinforced

pipeline

4 Maintenance

Outer lining may peel off with time. Hence, periodical maintenance is required

Outer painting may erode off with time. Hence, periodical maintenance is required,but frequency is less than MS pipe.

Lesser maintenance is required compared to MS and DI pipes

5 Life of pipeline Pipeline is designed for 10-15 years life

Pipeline is designed for 15-20 years life

Pipeline is designed for 50 years life. However, being applied only in recent times, it is not yet time-tested.

6 Design Obtained in standard sizes

Obtained in standard sizes

Optimized design can be effected by the manufacturer depending upon requirement

7 Weight & handling

Specific gravity = 7.85 Hence, it is about 4.4 times heavier than FRP pipes and thereby difficult to handle than FRP pipes

Specific gravity = 7.05 Hence, it is about 4 times heavier than FRP pipes and thereby difficult to handle than FRP pipes

Specific gravity = 1.8 to 1.9 Hence, it is easier to handle due to its lighter weight as compared to MS & DI pipes

8 .Thrust Block requirement

Thrust Block requirement is not there,as welded connection is provided

As spigot /socket tipe connection is provided,thrust block requirement is there.

Special connection can eliminate requirement of thrust block.

*C-Hazen Willims Constant




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6.0.0 CALCULATION PROCEDURE FOR OPTIMIZATION OF PIPE DIAMETER/THICKNESS FOR DIFFERENT MOCs

[In the calculation, the pipe diameter / thickness, buried piping has been considered as per the normal practice followed for cross-country piping, unless rock is encountered at close to top soil level.

Reasons behind this are :

1. With buried piping, cost of laying and supporting system become economic.

2. Obtaining ROW becomes easier and compensation against such ROW with buried piping is much less compared to overhead piping routing.]

The calculation procedure works out the design parameters and subsequently works out the capitalized life cycle cost for each of the alternatives and ultimately selects the most optimum choice. In case of long cross-country water piping of length exceeding 20-30 km., segmenting the piping system with one/multiple no. of booster stations may result in overall economy, as there can be substantial saving in cost of piping. Such option for long distance piping needs to be examined.

6.1.0 Basic Inputs for Calculation

The basic input data required for the calculation are as follows:

i) System Design Flow rate ii) Plant life iii) Trench dimensions including height of ground cover and water

cover over the pipe crown iv) Length of pipeline v) Pump & motor efficiencies vi) Pump & motor set cost[Based on the capacity,Head and Motor KW

to be calculated ] vii) Static head and pumping station loss viii) Number of hours the pumps will run in a year ix) Number of working pumps x) Prevailing power tariff xi) Escalation of power tariff per year xii) Civil costs (cost of excavation & backfilling) xiii) Interest rate xiv) Maintenance cost




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xv) Lining thickness (if any) / corrosion allowance * xvi) Cost of material, lining (if any), fabrication, pipe laying.

* For guideline of degree of wrapping/coating, recommendations in clause no. 8.2 of IS 10221-2008 may be referred.

6.2.0 Calculation Procedure

The procedure for calculation, in order to determine the most suitable and optimum pipe material, size and wall thickness for a given application, is elaborated below. The procedure is based on the guidelines laid down in AWWA M-11, AWWA M-45 and IS 8329 for MS Pipes, FRP Pipes and DI Pipes respectively.

6.2.1 Mild Steel Pipe

6.2.1.1 The calculation begins with the assumption of pipe NB and pipe thickness (t), from IS 3589.

6.2.1.2 Pipe OD is determined from IS 3589.

6.2.1.3 Pipe ID is calculated as, ID = OD 2t 2tL

Where, ID = Internal diameter of pipe,mm OD = External diameter of pipe,mm t = Pipe thickness,mm (assumed) tL = Internal liner thickness (IS 3589, Annexure A-

6.2, Table 8),mm

6.2.1.4 Check 1 : Checking for velocity :

Velocity of flow is calculated as,

V = Q / A

Where, V = Velocity of flow through pipeline,M/Sec Q = System Design Flow rate,M3/Sec A = Cross-sectional area of pipeline,M2 = (pi/4) * (ID/1000)2




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The velocity of flow should not be less than 1.2 m/s to prevent from precipitation of solid particles.This should also not exceed 2.5 M/Sec. in order to maintain the flow without the generation of vibration. With the initial assumption, if the above condition fails, pipe size and/or thickness are revised and the above calculations are repeated to satisfy the condition.There may be multiple diameters which will maintain the velocity criteria within the acceptable range.

6.2.1.5 Check 2 : Checking against failure due to internal pressure :

Head loss due to friction (hf) is calculated using Hazen Williams equation (Ref. AWWA M-11, eqn. (3-2M)). For MS pipe, friction co-efficient in Hazen Williams equation, C, shall be considered as 120.

Total pump head is thus, Hp = hf + hfm + Hs + hL

Where, Hp = Total pump head hfm = Margin on head loss due to friction Hs = Static head hL = Pumping station loss

Design internal pressure, PD shall be considered as 120% of total pump head (Hp) to take care of shut-off Condition.

Maximum allowable internal pressure that can be withstood by the pipe, with the selected diameter and thickness, is calculated using the Barlow formula (Ref. AWWA M-11, (eqn. 4-1)), with, t = assumed pipe wall thickness, and p = Maximum allowable internal pressure.

The following condition is checked, PD < p

On failure of the above condition, the pipe thickness is revised and the selected thickness is now applied in clauses 6.2.1.3 and 6.2.1.4 above to fine-tune the results. The selected thickness should also be checked as per clause 104.1.2 of ASME B 31.1 2001 (code for pressure piping) and higher value of thickness shall be considered.

6.2.1.6 Check3 : Checking against buckling due to internal vacuum / live load :

Allowable buckling pressure is calculated using eqn. (6-7), in AWWA M-11.




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Total external load on a buried pipe subjected to internal vacuum is calculated using eqn. (6-8), in AWWA M-11. In buried pipe applications, it is recommended to consider that the pipeline is subjected to full internal vacuum.

Total external load on a buried pipe subjected to live loads is calculated using eqn. (6-9), in AWWA M-11. Live load effect is obtained from Table 6-3. However, simultaneous application of live-load and internal vacuum transients need not normally be considered. For calculation of allowable buckling pressure, value of modulus of Soil Reaction is furnished in Table 6.10/AWWA M-11. However it should be considered as 500 psi (3450 kPa), unless specifically advised.

The total external load, as calculated above, should be less than the allowable buckling pressure. If the condition fails, the pipe wall thickness is revised and the previous calculations in clause 6.2.1.3 through 6.2.1.6 are repeated to satisfy the condition.

6.2.1.7 Check- 4 : Checking against failure due to stresses due to handling :

Minimum wall thickness for handling are based on the eqns. (4-5), (4-6), or (4-7) of AWWA M-11.

6.2.1.8 Check- 5 : Checking against deflection due to external pressure :

Load per unit of pipe length, W = WDL + WLL

Where, WDL = Dead load per unit length of pipe = WP + WL + WW WP = Weight of bare pipe per unit length

WL = Weight of internal + external lining per unit length

WW = Weight of water-filled pipe per unit length WLL = Live load per unit length of pipe, as per AWWA M-11, Table 6-3.

Horizontal deflection of pipe is calculated using eqn. (6-5) of AWWA M-11.

Allowable deflection is preferably 2% of pipe OD, for mortar lined and coated, 3% of pipe OD for mortar lined and flexible coated and 5% of pipe OD for flexible lined and coated.




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Horizontal deflection, as calculated above, should be less than the allowable deflection. In case the above condition fails, the pipe thickness is revised and the previous calculations in clauses 6.2.1.3 through 6.2.1.8 are repeated until the condition is satisfied.

6.2.1.9 Check- 6 : Checking against failure due to pressure surge :

Pressure rise above normal, due to water hammer, is calculated using eqn. (5-2M) and (5-3M) of AWWA M-11.

The total pressure during the surge is the normal working pressure plus the pressure rise above normal (as calculated above). In case this total pressure exceeds the maximum allowable internal pressure (as calculated in Cl. 6.2.1.5), either pipe thickness needs to be increased or surge suppression device needs to be incorporated. In cross-country pipeline applications, it is more economical to use surge suppression device to take care of the pressure surge instead of increasing pipe wall thickness.

6.2.1.10 Cost Analysis : From the above calculations, applicable pipe size(s) and thickness(s) are selected for the particular buried pipe application. For every set of selected pipe size and thickness, the following steps are undertaken to evaluate the cost of each pipe.

Capitalization factor is calculated as, CF = 1-CLc 1-C

Where, C = 1 + (Ep / 100) 1 + (Rf / 100)

Ep = Escalation of power tariff per year (%) Rf = Interest rate (%) Lc = Plant life (years)

Total piping cost, Cpipe = CBP + CL + CCW + CLAY

Where, CBP = Cost of the entire length of bare pipe CL = Cost of internal and external lining for entire

pipe CCW = Cost of civil works (excavation & backfilling) ** CLAY = Cost of laying of pipe




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** Cost of civil works (excavation & backfilling) shall be evaluated considering a standard trench, as shown below :

3Do

1000

D0

300

2Do

Total energy cost, CE = P * N * T * CF

Where, P = Power consumed in pumping N = Number of hours the pumps work in a year T = Power tariff

CF = Capitalization factor (as calculated above in in this clause)

Total evaluated cost, C = Cpipe + CE + CP+M + CM

Where, CP+M = Cost of pump set (pump + motor) CM = Maintenance cost (May be considered as 5%

of CE)

For every selected set of pipe size and thickness, the above calculations are done and the optimized set is determined. The optimized set is the one having the least value of Total evaluated cost, C.

D




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6.2.2 Ductile Iron Pipe

6.2.2.1 The calculation begins with the assumption of pipe size (NB), from IS 8329, and pipe class (K7 / K8 / K9 / K10).

6.2.2.2 Pipe OD is determined from IS 8329, Table 2.

6.2.2.3 The internal lining (Cement-mortar) thickness is obtained from IS 8329. The wall thickness of pipe is calculated using eqn (1) of IS 8329, Cl. No. 4.3.

6.2.2.4 Pipe ID is calculated as in Cl. 6.2.1.3.

6.2.2.5 Check- 1 : Checking for velocity : This checking is done as indicated in Cl. 6.2.1.4.

On failure of the condition, the pipe size and class is revised and the previous calculations are repeated to satisfy the condition. There may be multiple sets of NB and class which will maintain the velocity criteria within the acceptable range.

6.2.2.6 Check- 2 : Checking against failure due to internal pressure :

Head loss due to friction is calculated using Hazen Williams equation (Ref. AWWA M-11, eqn. (3-2M)). For DI pipe, friction co-efficient in Hazen Williams equation, C, shall be 140.

Total pump head and Design Internal Pressure is calculated as in Cl. 6.2.1.5.

The Allowable operating pressure (maximum allowable internal pressure) for the selected pipe size and class is then obtained from IS 8329, Annexure-E, Table 1.

The following condition is checked, Design internal pressure < Allowable operating pressure

On failure of the above condition, the pipe class is revised and the above calculations in clauses 6.2.2.4, 6.2.2.5 and 6.2.2.6 are repeated to satisfy the condition.

6.2.2.7 Check-3 : Checking due to failure against pressure surge : This checking is done as in Cl. 6.2.1.9.




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6.2.2.8 Cost Analysis : From the above calculations, applicable pipe size(s) and pipe class(s) are selected for the particular buried pipe application. For every set of selected pipe size and class, the following steps are undertaken to evaluate the cost of each pipe.

Capitalization factor, Total piping cost, Total energy cost and Total evaluated cost is calculated as in 6.2.1.10.

For every selected set of pipe size and pipe class, the above calculations are done and the optimized set is determined. The optimized set is the one having the least value of Total evaluated cost, C.

6.2.3 FRP Pipe

6.2.3.1 Apart from the inputs mentioned in Cl. 6.1.0, the design of FRP pipe requires the following additional inputs :

i) Nominal pipe size (ref. IS 12709, Table 1 or Table 2). ii) Hydrostatic design basis (manufacturers data) iii) Long term ring bending strain (manufacturers data)

6.2.3.2 The calculation begins with the assumption of pipe NB, Pressure class, PC, (ref. IS 12709, Cl. 4.1.1) and pipe reinforced wall thickness, t.

6.2.3.3 If ID series pipes are used, then, pipe ID, for the assumed pipe NB, is obtained from IS 12709, Table 1. If OD series pipes are used, then, pipe OD is determined from Table 2 and pipe ID is calculated as in Cl. 6.2.1.3. The internal lining thickness for FRP pipes is obtained from manufacturers data. It is generally between 1-1.2mm.

6.2.3.4 Check-1 : Checking for velocity : This checking is done as indicated in Cl. 6.2.1.4. On failure of the condition, the pipe size and wall thickness is revised and the calculations in clauses 6.2.1.3 (pipe ID) and 6.2.1.4 are repeated to satisfy the condition. There may be multiple sets of pipe sizes & thickness which will maintain the velocity within the acceptable range. It is to be noted here, that the maximum velocity that can be allowed for safe operation of FRP pipe is determined using eqn. (4-1) of AWWA M-45. the minimum velocity to maintain the flow shall be 1.2 m/s.

6.2.3.5 Check-2 : Checking Pressure class : The acceptability of the selected pressure class, PC, is checked using eqn. (5-1) or eqn. (5-2) of AWWA M-45. In case the condition fails, the pressure class and pipe wall thickness is simultaneously revised and above calculations are repeated to satisfy the condition.




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6.2.3.6 Check-3 : Checking against failure due to internal pressure :

Head loss due to friction is calculated using Hazen Williams equation (Ref. AWWA M-11. eqn. (3-2M)). For FRP pipe, friction co-efficient in Hazen Williams equation, C, shall be 150.

Total pump head and design internal pressure is calculated as in Cl. 6.2.1.5.

The eqn. (5-3) of AWWA M-45 is checked with Pw being the calculated design internal pressure. In case the condition fails, the pipe wall thickness and pressure class is simultaneously revised and the above calculations in clauses 6.2.3.4, 6.2.3.5 & 6.2.3.6 are repeated until the condition is satisfied.

6.2.3.7 CHECK 4 : Checking against failure due to pressure surge :

Pressure surge above normal is calculated using eqn. (4-21) of AWWA M-45. Here, a full instantaneous change in velocity equal to the flow velocity in the pipe shall be considered.

The eqn. (5-4) of AWWA M-45 is checked. In case the condition fails, the pressure class and wall thickness is simultaneously revised and the above calculations in clauses 6.2.3.4, 6.2.3.5, 6.2.3.6 & 6.2.3.7 are repeated until the condition is satisfied. The pressure surge for FRP piping will be lower compared to MS/DI Pipe for same parameters.

6.2.3.8 Check-5 : Checking for maximum allowable deflection due to ring-bending :

Pipe stiffness class, PS, is assumed (Ref. AWWA M-45, Table 5-1).

From eqn. (5-5) or eqn. (5-6) of AWWA M-45, the maximum allowable long-term vertical pipe deflection is calculated.

For proper design, maximum allowable long-term vertical pipe deflection, as calculated above, should be greater than the permitted deflection (generally 5%). In case the above condition fails, the pressure class, wall thickness and pipe stiffness are simultaneously revised and the above calculations in clauses 6.2.3.4 through 6.2.3.8 are repeated until the condition is satisfied.




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6.2.3.9 Check-6 : Checking against failure due to deflection :

Vertical soil load, WC, is calculated using eqn. (5-9) of AWWA M-45, Cl. 5.7.3.5 and Live Loads on pipe, WL, as per the guidelines in Cl. 5.7.3.6 of AWWA M-45..

Constrained soil modulus, MS, is calculated as per Cl. 5.7.3.8 of AWWA M-45.

The predicted deflection is calculated using eqn. (5-8) of AWWA M-45. In case the predicted deflection is greater than permitted deflection, the pipe stiffness, pressure class and wall thickness is simultaneously revised and the above calculations in clauses 6.2.3.4 through 6.2.3.9 are repeated until the condition is satisfied.

6.2.3.10 Check-7 : Checking against failure due to combined loading of internal pressure and deflection : The checking is done as per Cl. 5.7.4 of AWWA M-45. In case the condition fails, the pressure class, wall thickness and pipe stiffness class is simultaneously revised and the above calculations in clauses 6.2.3.4 through 6.2.3.10 are repeated until the condition is satisfied.

6.2.3.11 CHECK 8 : Checking against buckling due to internal vacuum or live load :

Allowable buckling pressure is calculated using eqn. (5-24a) of AWWA M-45. Here, EI is calculated using eqn. (5-18) of AWWA M-45.

Total external load on a buried pipe subjected to internal vacuum is calculated using eqn. (5-25) of AWWA M-45. In buried pipe applications, it is recommended to consider that the pipeline is subjected to full internal vacuum.

Total external load on a buried pipe subjected to live loads is calculated using eqn. (5-26). Live load is calculated as per Cl. 5.7.3.6 of AWWA M-45. However, simultaneous application of live-load and internal vacuum transients need not normally be considered.

The total external load, as calculated above should be less than the allowable buckling pressure. If the condition fails, the pressure class, wall thickness and pipe stiffness is simultaneously revised and the above calculations in clauses 6.2.3.4 through 6.2.3.11 are repeated until the condition is satisfied.




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6.2.3.12 Cost Analysis : From the above calculations, applicable pipe sizes with pressure class, reinforced wall thickness and stiffness class are selected. For every selected pipe, the following calculations are done to evaluate the cost of each pipe.

Capitalization factor is calculated as in Cl. 6.2.1.10.

Total piping cost is, Cpipe = (U * L) + CCW

Where, CCW = Cost of civil works (excavation & backfilling) (Calculated as in Cl. 6.2.1.10) U = Unit rate of pipe (Rs/m) (manufacturers data) L = Length of pipe

Total energy cost, CE, and, Total evaluated cost, C, is calculated as in Cl. 6.2.1.10.

For every selected pipe, the above calculations are done and the optimized pipe is determined. The optimized pipe is the one having the least value of Total evaluated cost, C.

7.0.0 RESULT

Based on the analysis above, the optimum choice of diameter / class (thickness) and MOC can be found out. Such optimized parameters will form the basis of subsequent procurement activity.

8.0.0 REFERENCES

1. AWWA M 11 : Steel Water Pipe : A Guide for Design and (Fourth Edition) Installation.

2. AWWA M 45 : Fiberglass Pipe Design (Second Edition)

3. IS 3589 : Steel Pipes for Water and Sewage (168.3 to (Third revision) 2540mm outside diameter specification)




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4. IS 12709 : Glass Fiber Reinforced Plastics (GRP) Pipes, (First revision) Joints and Fittings for use for Potable Water Supply Specification

5. IS 8329 : Centrifugally Cast (Spun) Ductile Iron Pressure (Third revision) Pipes for Water, Gas and Sewage Specification

6. FLOWTITE Test Report on Hydrostatic Design Basis (strain)

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Sep Cross Country Piping