223000-ma-rs-000-0022_protesa_hidraulic_pressure_test_procedure.pdf

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ABEIMA TEYMA GHANA

Desalination Plant Nungua

The original copy of this document is electronically signed and filed in the document management system of Abeima Teyma Ghana.

Quality Documents

Title:

Protesa: GRP Pressure Test Procedure

Document No.: 223000-MA-RS-000-0022

Revision: 00

Date: 17/01/2014

Prepared by:

David BrdaloProject Manager. DB

Reviewed by:


Approved by:


This document is property of Abeima Teyma Ghana. Its total or partial reproduction is strictly forbidden by any means, as well as itsdistribution to third parties without the express written consent of Abeima Teyma Ghana.

If for exceptional reasons, due to specific aspects of the project (eg: project confidential information, legal requirements or local regulationsand/or contractual requirements of the client), there was a need to modify the requirements included in this procedure, these changes mustbe properly documented in the quality, environment and health and safety plan of the project, prior approval from the companyheadquarters management system department.


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ABEIMA TEYMA GHANA

Desalination Plant Nungua

Document: 223000-MA-RS-000-0022

Revision: 00 Date: 17/01/2014

Page: 2 of 2

Revision Control Sheet

Revision Date Reason for the revisionPrepared

byReviewed

byApproved

by

00 17/01/2014 Initial DB DB DB


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This procedure is based on the December 2005 edition of the standard UNE-EN 805,related to Water Supply.

As the installation of the GRP pipes progresses, partial pressure tests should becarried out on sections that have been prepared for this purpose.

The length of these sections must be established by the Site Management, but it isrecommended that they are between 500 and 2000 m, providing that the difference inpressure between the lowest and highest ground points does not exceed 10% of thetest pressure.

Prior to performing the pressure test, the pipes should be covered with the specifiedbackfill, which should be compacted according to the project specifications.

The water should be let into the lower part of the pipe to enable all of the air to bereleased through the upper part, or air outlets should be positioned at high points, toensure that it is removed.

The pipe should be prepared according to a series of measures to ensure that it isstable whilst carrying out the test

The soil base on which the block is to be constructed must be able to withstand its load

without deformation. If this is not the case, the appropriate measures should be takento ensure that it is stabilized.

At the points of the pipe at which there are horizontal or vertical changes in direction,changes in cross-sectional area (reducers), air outlets, connections or branches, lineterminations, etc., it is necessary to construct anchor blocks to counteract thrust forcesdue to the water pressure and prevent displacement caused by internal pressure.

The resisting forces, which oppose the hydraulic thrust, are considered to be the weightof the anchor block itself (the friction coefficient at the soil-concrete interface) and thepassive resistance of the soil.

These blocks increase the resistance of the fittings to the movements of the fluid due tothe increased bearing area and the dead weight around the fitting itself. They must be

specifically sized to withstand the thrust forces exerted by these special pieces. Thecharacteristics of the anchor blocks depend upon the nature of the soil, the diameter ofthe pipe, the service pressure and the burial conditions.


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In installations on steep slopes, pipe assembly should be carried out in an ascendingdirection, with the addition of transverse anchor blocks to prevent the pipe fromslipping. It is recommended to position the anchor blocks across short pipes toguarantee the flexibility of the installation.

For practical purposes, the blocks are sized to counteract the maximum hydrostaticthrust generated by the maximum internal pressure in the pipe (test pressure, waterhammer, etc.), and both its magnitude and direction should be taken into account.

The shape and dimensions of the concrete blocks used as anchors depend upon theshape of the element to be anchored, the thrust caused by internal pressure, soilresistance and any other further loads.

Fig. 1 Different definitions of thrust depending on Pressure (P) and cross-section (A).

Fig. 2 In installations with slopes of over 10%, measures need to be taken to anchor the pipe (detail ofthe anchoring of GRP pipe sections and of a vertical elbow).


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In the case of vertical changes in direction, the anchor block should have metal bandsencrusted into the concrete, which are duly protected against corrosion. The anchorblock should never obstruct the pipe, but should simply resist the thrust generated bythe internal pressure, in a specific direction. The joints at either side of the anchoringelement should remain accessible.

In order to determine the dimensions for each anchor block, it is necessary tocalculate the resultant force of the thrust corresponding to the predicted maximumpressure for tests on site and also take into account the soil resistance.

Line blocks are conceptually different from thrust blocks. They are used to control axial

movement in straight sections of piping, caused by abrupt changes in pressure (waterhammer) or by thermal gradients. They may also be used in installations withpronounced slopes.

These blocks are generally made of weak concrete (50-70 Kg/m3), which is pouredover the natural slope of the pipe, ensuring that the upper surface of the block has aminimum length equal to the diameter of the pipe. The piping must have a GRP rib toenable it to be anchored and prevent it from sliding.

Fig. 3 Anchor blocks for changes in direction of just a few degrees.

Fig. 4 Diagram of different GRP reinforcements


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Valves, or any other type of mechanical equipment installed in the pipe which maygenerate thrust, must be anchored to a block, in order to discharge onto it anymaneuvering force and the thrust that is generated when the valve is closed.

All of the outlets from the main pipe, stub-ins for air release valves, inlets, drainagepipes, intakes, etc., should be restrained in terms of axial forces by means of therelevant anchoring blocks.

Fig. 5 Diagram of an anchor block for mechanical elements such as valves.

Fig. 6 Diagrams of different ways of anchoring special pieces.


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For the purposes of this procedure, the following definitions shall apply with respect topressure:

Abbreviation DP MDP STP PFA PMA PEA OP SP

DefinitionDesign

Pressure

Maximum

Design

Pressure

System

Test

pressure

Allowable

Working

Pressure

Maximum

Allowable

Pressure

Allowable

Site Test

Pressure

Operating

Pressure

Service

Pressure

Relating to the System Relating to the ComponentsRelating to the

System

- Maximum Allowable Pressure (PMA): This is the maximum pressure,including water hammer, that a component is capable of withstanding whilst inservice

- Allowable Working Pressure (PFA): This is the maximum pressure that acomponent is capable of withstanding permanently whilst in service.

- Allowable Site Test Pressure (PEA):This is the maximum hydrostaticpressure that a recently installed component can withstand for a relativelyshort duration, with the aim of ensuring the integrity and watertightness of thepiping.

- Design Pressure (DP):This is the maximum working pressure of the system or

pressure section (for continuous service) established by the designer,considering future extensions but excluding water hammer.

- Maximum Design Pressure (MDP): This is the maximum working pressure ofthe system or of a particular pressure area, established by the designer,considering future extensions and including water hammer, where:

MDP is expressed as MDPa, when an allowable water hammer valuehas been established in advance.

MDP is expressed as MEPC, if the water hammer is calculated.

- Operating Pressure (OP): This is the internal pressure which arises at anygiven moment at a certain point in a water supply system.

- Service Pressure (SP):This is the internal pressure at the connection point tothe consumers installation, with no water in the branch pipe.

- Water Hammer: Rapid fluctuations in pressure due to variations in the flowover short periods of time.

- System Test Pressure (STP): This is the hydrostatic pressure applied to a

recently installed pipe in such a way as to ensure its structural integrity andwatertightness.


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Before carrying out the pressure test, the pipes should be covered, where appropriate,with filling material, in order to prevent variations in the soil conditions which couldcause leaks.

Backfilling of the joint area is optional. The definitive restraints and anchoring blocksshould be constructed to withstand the thrust resulting from the pressure test. Theseconcrete restraints or anchoring blocks should have reached the required

characteristics in terms of resistance before the testing commences. Care should betaken to ensure that any provisional plugs or closed-off ends are appropriately fixeddown and that the forces transmitted into the soil are adequately distributed accordingto the soils bearing capacity. No temporary support, restraint or anchor should bewithdrawn from the ends of the test section until the line has been depressurized.

It is recommended to restrain any blind flanges by means of some type of support tocounteract the action of the thrust forces against the flat surface.

The pipeline should be tested in its entirety, or, if necessary, divided into severaldifferent test sections.

The test sections should be selected with the aim of ensuring that:

- The test pressure can be applied to the lowest section of each test section;- The volume of water necessary for the test can be supplied and drained without

any difficulty.

Any debris or foreign bodies should be removed from the pipeline before the test

commences. The test section should then be filled with water. For potable waterpipelines, potable water should be used for the pressure test, unless otherwisespecified by the designer.

The pipeline should be purged of air, as far as reasonably possible, and it should thenbe filled slowly, if possible from the lowest point of the line, in order to prevent airpockets from forming. Any air is thus evacuated through purging devices, which shouldbe adequately sized.


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For all pipelines, the system test pressure (STP) should be calculated based on themaximum design pressure (MDP) in the following way:

- Calculated water hammer: STP = MEPC+100kPa

- Estimated water hammer: The lesser of the two values

The test procedure should be specified by the designer and may include the followingthree phases:

- Preliminary test.- Purge test.- Main pressure test.

The necessary phases should be specified by the designer.

The preliminary test is carried out with the following aims:

- To stabilize the section of the pipeline that is going to be tested, allowing a

certain amount of movement to take place, which tends to occur within a certaintime.

- To achieve the appropriate level of saturation in all water-absorbent materials.

- To allow for an increase in volume depending on the pressure in flexible piping,before the main pressure test.

The pipeline should be divided into practicable test sections, which are completely filledwith water and purged, and the pressure should be increased, always at a speed lower

STP=MDPax1.5

STP=MDPa+500kPa


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than 10 kPa/min, to at least the operating pressure, without exceeding the system testpressure (STP).

If unacceptable changes in position occur in any part of the pipeline, and/or leaksappear, the pipeline should be depressurized and the faults corrected.

The duration of the preliminary test depends upon the pipe material and should bespecified by the designer, taking into account the applicable product standards.

The purge test allows an estimate to be made of the volume of air remaining in thepipeline.

Any air remaining in the test section may produce erroneous data which could indicate

an apparent leak or, in some cases, may disguise small leaks. The presence of air willreduce the accuracy of both the pressure-loss and water-loss tests.

The designer should specify whether or not the purge test should be carried out.

The main pressure test should not commence until the preliminary test and, if required,the specified purge test have been satisfactorily completed.

The effect of great variations in temperature should be taken into account.

Two basic test methods are permitted:

- The water-loss method;

-The pressure-loss or drop method.

The designer should specify which method is to be used.

Two equivalent methods can be used to measure water loss, for example, ameasurement of the volume discharged or a measurement of the volume pumped(injected), as described in the following procedures.


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- Measurement of the discharged volume:

The pressure is increased at regular intervals until it reaches the system testpressure (STP). The STP is maintained by means of pumping, if necessary, for

a period of at least one hour.

The pump is disconnected and no more water is permitted to enter into the pipefor a one-hour test period or for a longer period of time, if specified by thedesigner.

At the end of this period, the pressure reduction is measured and the STP isrecovered by pumping. The loss is then measured by draining water until theprevious reduced pressure is reached again.

- Measurement of the pumped (injected) volume:

The pressure is increased at regular intervals until it reaches the system testpressure (STP). The STP is maintained for a period of at least one hour, orlonger if specified by the designer.

The quantity of water which needs to be pumped to maintain the system testpressure is measured and recorded using an appropriate device,

The designer should specify which method is to be used.

Acceptable water loss at the end of the first hour of the test should not exceed thevalue calculated using the following formula:

Where:

Vmax maximum volume to be added (liters) V volume of the test section (liters) P allowable pressure loss (in GRP, 20 kPa) EH2O modulus of compressibility of the water in kPa ER ring flexural modulus of elasticity of GRP (kPa) DN inside diameter of the pipe (meters) e thickness of the pipe wall (meters) 1.2 correction factor (for example, for residual air) during the main

pressure test

+=

RW

mxEe

D

EpVV

*

1**2.1

.


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The pressure is increased at regular intervals until it reaches the system test pressure(STP). The duration of the pressure-drop test should be 1 hour or longer, if specified

by the designer. During the test, the pressure drop p should present a downwardtrend and after the first hour should not exceed the following value:

20 kPa for piping made of plastic materials, in our case, GRP.

If the loss of watertightness exceeds the specified value or if defects are found, thepipeline should be examined and corrected where necessary. The test should be

repeated until its results meet the specifications.

If the pipeline has been divided into two or more test sections and they have allsuccessfully passed the pressure test, the entire pipeline should then be subjected tothe systems operating pressure (OP) for at least two hours, if specified by thedesigner. Any additional (untested) components incorporated into adjacent sectionsonce the pressure test has been carried out should be visually inspected for leaks and

changes in level and alignment.

A complete report with the details of the tests should be produced and filed and thehydraulic test performance certificate, including the pressure ratings, the DN, etc., ofthe tested lines should also be filled in.