maintenance manual rev 3(repair)

8/14/2019 Maintenance Manual Rev 3(Repair)

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Section 6 of Document # MM/200700

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Date 08-06-2004

Repair Procedures of GRP/GRV Piping System


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REPAIR PROCEDURES OF FUTURE PIPE INDUSTRIES GLASSFIBRE REINFORCED

PIPELINE SYSTEMS

(GRP/GRV)

1. 1. Introduction

The following document is intended to be used as a guideline for maintenance and repair of

Fiberglass pipelines. Different repair methods are described in the following pages and thecontractor will choose what best fit his site conditions.

It is recommended to have a small quantity of spare parts to minimize the downtime.

a) 2. Symbols

The different joining methods are represented by the following symbols:

3. Repair of defects in the straight pipe section

Before installation it is necessary to inspect the pipe on damages caused by the transportation or

storage.

In this case the particular part shall not be installed. Ask the manufacturer for advice about theprocessability of this particular part.

If leakage appears after installation or during operation of the system, this can be repaireddepending on the type of joining. Leakage in a straight pipe can be caused by the carelessness

during digging or falling objects.


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If existing pipelines are damaged, they can start leaking and therefore the damaged part should beremoved from the system. It is available to replace the pipe over a distance of W (m) on both

sides of the damaged spot. The length depends on the diameter for the determination of W (m) seetable 1.

For the different joining systems applied in the pipeline system several repair methods aredescribed starting from the principle of standard lengths of pipe. A combination of the different

joining techniques for repair is also possible.

If by lack of time the described procedures cannot be followed a temporary repair by means of abutt and strap joint can be executed as described in section 3.2.

Table 1. Length of the piece of repair W

ID (mm) W (m)

25 - 50 0.580 - 600 1.0

700 - 1200 1.5above 1200 3.0

3.1 Straight pipe-line section with external coupler

a) Mechanical Coupler

Schematically the repair method can be represented as follows:

Figure 1


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If a pipeline system provided with external couplers leaks, a piece of at least W (m) must be

replaced. Remove the two couplers, connected to the part, which has to be repaired, from the

continuing line. According to the described procedure of chapter 6 a piece of at least W (m)has to be cut of the damaged pipe.

The saw cuts of the remaining pipe and those of the repair part must be coated with resin in

order to prevent the medium attacks the open glass roving.

The external mechanical couplers can be moved over the pipe. The now available 3 parts

(pipeline parts and repair part) can be replaced in the system by means of 2 new mechanicalcouplers. If the coupler itself leaks, it must be dismounted and carefully inspected on

cracks in the rubber sealing.

If there are cracks the coupler must be replaced.

b.) With GRP Coupler

This procedure is applicable for the GRP unrestrained underground pipe supplied.

3.1.1 If a pipe line system provided with coupler leaks, a piece of at least W (m) must bereplaced. Remove the damage piece and examine the ends of the still installed pipe.

If both are spigot go to section 3.1. If they are plain ended, start by calibrating themusing the site shaver machine available and then go 3.1.2

3.1.2 Placement of Pipe and Making Closure

1. Carefully measure the space where the closure pipe is to be placed. The closurepiece must be 50mm shorter than the length of the space. The piece must becentered with an equal clearance of 25mm left between the inserted pipe and the

adjacent ones.


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2. Use a special pipe with long machined ends ordered or prepared specifically forthis purpose.

3. Use two special Double Bell couplings or two wide-type flexible steel

couplings.

4. Pull the couplings onto the machined ends of the closure pipe after lubricating

abundantly the ends and the rubber ring. It may be necessary to gently help thesecond ring over the chamfered end of the pipe.

5. Lubricate well the ends of the two adjacent pipes after they are cleanedthoroughly.

6. Place the closure pipe in its final position and pull the coupling over the adjacentpipes up to the home line (Fig. 6-13, steps 2 & 3).

3.2 Straight pipeline section with butt and strap joints

Repair of leakage in a straight pipeline section, being part of the pipeline system by means of

butt and strap joints, is basically executed on the same way as the repair of a pipeline sectionprovided with external mechanical couplers.

On a distance of W (m) on both sides of the leak, the pipe will be cut, as described in chapter6. The ends of cut pipe and the replacing part has to be beveled off in order to make a butt and

strap joint as described in chapter 7.

Schematic way of representing of repair procedure.

Figure 2


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By this method of repair it is of great importance to cut the replacement pipe as precise as

possible, in which the squareness of the cut is determining.

The width of gap between the pipe parts is determining for the reliability of the joint. Beforestarting the repair procedure one must be sure that the pipe is dry and no fluid can get nearbythe section to be laminated.

If leakage occurs in a laminated joint, this part has to be removed and replaced by an adaptor

using the same procedure as described before.

The materials needed for this method of repair are:

- 2 lamination sets of the particular diameter and 1 adaptor with a length of W (m).


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3.3. Straight pipe-line section with flange connection

Leakage in pipe systems with flange connections can also occur as described before as well as inthe connection itself as in the pipe part on which these flanges are joined.

Leakage of the flange connection can be caused by a wrong torque of the bolts. The torques forthe diameters are indicated in table 2.

Table 2.

Torques for flanged joints (Nm) with full- face gaskets

ID

(mm)

DIN 1882

DIN 2501 ND16

ASA 150

DIN 2501 ND 25

ASA 300

DIN 2501 ND25 API 75

25 100 100 10040 100 100 150

50 100 100 15080 100 100 150

100 100 100 250

150 150 150 250

200 150 150 300250 150 300 500

300 150 300 550

350 150 300 700

400 300 500 700450 300 550 800

500 300 700 800600 400 700 1300

700 400 700 1300 100750 400 700 100

800 600 1200 100

900 600 1200 1501000 600 1300 200

1200 1000 1300 200

When using glassfibre-reinforced flanges in a pipeline system the designer and installer must

supervise the installation against flat-faced flanges. When tightening flat-faced glassfibre


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reinforced flanges against raised -face flanges using the above mentioned torques, the allowablebending stress in the glassfibre reinforced flanges will be overstepped and results in cracking theneck of the flange.

Glassfibre-reinforced flanges are flat-face and are provided with two concentric sealing ribs.

Raised-face flanges should be turned off to flat-face.

If this procedure is not possible the annular void should be filled with a hard gasket material or a

spacer ring.

Tighten all nuts in increments following a diagona l sequence to the required torque as per theFlange Torqueing Procedure.

After ten minutes any leakage should be stopped.

If the joint is still leaking the gasket has to be removed and replaced by a new one.

3.3.1. Cemented flange connections (diameters thru 300 mm)

A repair method of a pipe with flanges is possible using a cement joint.

The schematic presentation of this procedure is given in figure 3.

Figure 3

After dismounting of the flanged pipe section its length must be measured and a straightline is drawn between two facing boltholes. Hereafter the section to be repaired has to becut out of the pipeline over a distance of W (m) on both sides of the leak.


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The adaptor with a length W(m) also will be marked with a line parallel to the axis of thepipe. For cutting see Chapter 6.

Spigot ends will be shaved on the cut pipe parts using the shavers. The three preparedpipe parts will be assembled dry. The total length of the assembled parts has to be equal

to the defect pipe section. Then the three pipe parts will be cemented with the aid ofdouble. Socket couplers, making sure that the marks on the pipe parts will be in evenline.

For cement instructions see assembly instructions (packed together with the cement kit).

After cementing and curing the repaired pipe section will be installed with new gaskets.

The materials needed for these repair methods are:

- 2 double socket couplers, 1 adaptor with length W (m), cement kits and 2 gaskets.

Note: The assembly length of double socket coupler is 4 mm.

3.3.2 Laminated flange connections (diameter 350 mm and upwards)

A repair method of a pipe section with flanges is possible using a butt and strap joint.

The schematic presentation of this procedure is indicated in figure 4.

Figure 4


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After dismounting of the flanged pipe section its length must be measured and a straightline is drawn between two facing boltholes. Hereafter the section to be repaired has to becut out of the pipeline over a distance of W(m) on both sides of the leak.

The adaptor with a length W(m) also will be marked with a line parallel to the axis of the

pipe. For cutting see chapter 6. Laminating is described in chapter 7.

Be sure that the marks on the pipe parts are in even line before laminating. This

procedure also can be executed without dismounting the flanges, however on conditionthat there is enough room for laminating and drying of the pipe line in-and external.

The materials needed for the first mentioned method is:

- 2 lamination sets and 1 adaptor with a length of W (m) and 2 gaskets.

For the last mentioned procedure the same items with exception of the gaskets are needed.

3.4. Straight pipe section with cement joint (diameters thru 300 mm)

Schematic presentation of the repair method:

Figure 5

Repair of pipe sections connected by means of cement joints shall be done identical to thedescription chapter 3.2.

If leakage occurs in the cement joint itself, the joint should be cut out of the pipe section over alength of the adaptor of W (m) after which a new connection can be made by means of two butt


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and strap joints and an adaptor with the same length as the removed coupler. the same procedurewill be followed if leakage occurs in he pipe itself.

In both cases the ends of the pipe section and the adaptor must be cut exactly square (see chapter6) & then beveled on behalf of the butt and strap procedure described in chapter 7.

For this procedure is needed: an adaptor with a length W(m) and two lamination sets of theparticular diameter.

4. Repair of defects in fittings

Before installation of a fitting it is necessary to inspect the particular fitting on damages that mightoccur by transportation and/or storage. In case of damage the proper functioning of the fitting is

doubtful, this part should not be installed. Ask manufacturer's advice.

If after start up of the pipe line system a fitting leaks caused by external damage or another reason,the fitting must be replaced on one of the methods described hereafter.

If by lack of time the described method cannot be executed, in some cases a temporary repair canbe done as described in chapter 5. Later on the definite repair can be executed.

For simplicity reasons we assume the fitting to be repaired will be a T-piece.

4.1. Fitting with external mechanical couplers

By disassembling the external mechanical couplers, the defect fitting can be removed andreplaced. These mechanical couplers e.g. (Strap, Tayer Kerr, Viking Johnson, Dresser) can bemoved over the ends of the fitting or the connected pipe/fitting.

If leakage occurs in the coupler itself, it must be carefully inspected on cracks in the sealing

rubber.

If there are any defects in the sealing the couplers must be replaced.

The assembly of this type of couplers should be done on a proper cleaned surface, in the

meantime the sealing of the coupler must be cleaned.

For this repair procedure couplers and/or a fitting are needed.

4.2. Fitting with butt and strap joints


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If leakage occurs in a fitting, which is connected, to a pipe system by means of butt and strapjoints, it is necessary to cut out this fitting next to these joints and replace a fitting with equaldimensions of the removed part.

For cutting see chapter 6. For laminating see chapter 7. Before cutting the dimensions of the

part to be repaired have to be measured and drawn, as accuracy of cutting is determining for thereliability of the joint to be made. For this described repair procedure the following materials areneeded: a fitting with dimensions equal to the cut one, a number of lamination sets equal to the

amount of joints of the particular fitting.

Schematically this repair method can be presented as follows:

Figure 6

4.3 Fittings with flanged connections

If leakage occurs in the fittings itself, it shall be disassembled and replaced completely.

Leakages, in the flange connection itself can be caused by a wrong torque, a leaking gasket or afitting, which is fitted under tension. The bolts of a flange connection should be tightened in

increments following a diagonal sequence according to fig. 3 After the maximum torque has beenapplied in accordance with the values mentioned in table 2 of chapter 3.3 the leafage should stopwithin 10 minutes. If the joint still leaks the gasket must be replaced.

For the execution of this repair method the following materials are needed:

- a fitting with the right dimensions and a number of gaskets.


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Section 6 of Document # MM/200700Revision: 0

Date 08-06-2004

4.4. Fitting with cement joint

Figure 7

Because it is not possible to replace a cemented joint from a pipeline by means of a cement

joint it is necessary to use a butt and strap joint. The leaking fitting must be cut out of the pipelineon such manner that the saw outs are on a distance of the standard dimensions of the fitting + W(m). For cutting and laminating see chapter 6 and 7.

For this repair method are needed:

- an elongated fitting and an amount of lamination sets equal to the number of the fittingends.

5. Temporary repair

If due to circumstances a radical repair cannot be executed, in some cases one may decide to do atemporary repair.

However you should take care that the final repair must be executed within a certain period, ineither case it must be done within 3 months. By the defect the fluid will penetrate into the

laminate and might attach the open glass rovings, It might happen that the medium to betransported will be forced over a great distance into the laminate, which should be prevented.

5.1 Temporary repair by means of laminating


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One of the temporary repair methods is covering the outside of the defect by a laminate. For thispurpose the pipeline has to be made pressureless and dried to provide that the laminate to bemade gets wet.

The area of the topcoat around the damage with the dimensions of the diameter should be

removed by means of a grinder. With a heater the ground surface should be dried, withoutburning this surface. The resin/ hardener mixture should be prepared and the ground surface bewetted by means of a roller or brush. Then in turns a layer woven roving and a layer resin

mixture should be applied taking into account, that every next layer should be applied after theprevious one has been fully impregnated with resin.

The thickness of the layer to be applied is about 1 times the thickness of the pipe wall to berepaired.

After applying the repair laminate it must be cured.

Depending on the type of hardener, which has been used, curing can be done in open air or bymeans of heating. To accelerate the curing, heating can be used in the form of a heater or a

heating blanket. The heating blanket should be positioned if the laminate is pre-cured or does notfeel tacky. The laminate also can be covered with foil after which the curing blanket should be

placed. If a heater has been used one should take care that the resin does not catch fire.

After curing has been completed and the repaired laminate has been cooled, the pipeline can be

pressurized.

For description of the laminating technique see chapter 7. For the repair method are needed: alamination set of the particular diameter.

5.2. Temporary repair by means of cementing a pipe segment

A second method to carry out a temporary repair is cementing a pipe segment over the damagedpipe section. In fact this repair is identical to the method described in chapter 5.1., but instead ofapplying a laminate, prefab laminate in the shape of a pipe segment is taken.

Figure 8


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Surface to be ground

and sealed

leak

3 - 5 cm

3-5cm

Before starting the repair procedure the pipe system must be pressureless and the mediumpumped out to a level below the surface to be ground. A surface as large as the part to becemented shall be ground around the leak. The inner surface of the segment to be cemented

should be ground to fit, after which the cement surfaces should be dried by a heater.

Now the components of the cement can mixed and mixture can be applied to the contact surfaces

by means of a spatula or a rubber plate.

For description of the cement procedure see the assembly instructions (packed with the cement).

After cementing the two parts together, they shall be pressed together by means of clamps.

The visible ground surface shall be sealed with resin.

Then curing can start according to the instructions, after which the pipe system can bepressurized. For this repair method is needed: a cement kit and a segment with clamps.

5.3. Temporary repair by means of clamps

A simple method to stop leakage is using rubber lined divisible clamps, which can be mounted,over the pipe section to be repaired. Several manufacturers, such as Dresser, Georg Fischer,

Waga, supply repair parts. For small leaks a simple rubber lined clamp made by the contractor

himself, can be used. Once the water stops, a lay-up shall be made to cover the clamps. The lay-up shall be extended at least 300 mm from each side of the clamp.

6. Cutting

The cutting of glassfibre reinforced epoxy pipes can be done by means of metal saw (for smalldiameters) or a grinding wheel (diagrit or carborudum).


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The pipe section to be cut shall be marked off using a marker along a pipe wrap - a- round afterwhich the cutting can be made using a hack-saw.

As the reliability of the connection to be made depends on the squareness of the saw cut, it is

necessary to pay attention to this operation.

If a pipe should be cut to make a butt and strap joint the cut end of the pipe should be leveled off,

in the meanwhile the cross cut should be protected against penetrating liquid using a resin ofcement layer. The maximum gap between the pipe sections to be joined is 3 mm. If a spigot end

is shaved on behalf of a cement joint the end of the pipe will be beveled off automatically.

7. Butt and strap joint

Carrying out a butt and strap joint the following procedures should be followed.

After the pipe sections to be laminated have been cut square the outer surface of the pipe sections

have to be ground in order to obtain a clean and rough bonding surface. The length of surface tobe ground (L) depends on the diameter of the butt and strap joint.

ID thru - 50 mm L = 1.2 ID (mm)ID 80 - 300 mm L = 0.8 ID (mm)

ID 350 - 1200 mm L = 0.5 ID (mm)

The pipe ends should be beveled off to an angle of 30 - 45 with the axis of the pipe (see Fig. A)and the ground surface should be cleaned with a clean cloth.

Before starting the butt and strap procedure the parts to be connected must be dried carefully.

This can be done using a heater or a heating blanket.

The component resin/hardener must be mixed. The ratio is mentioned on the packing or in the

instructions enclosed.

The cross section of the pipe has to be protected against penetrating liquid using a resin or

cement layer.

- The erected pipe sections should be wetted over a length of 5 cm on both sides of the "weld"using resin/hardener mixture, after which the fit layer can be made.

- Wrap 4 layers of 280 gr./m or 270 gr./m2 woven roving around this "weld" taking care thatevery following layer is applied over a totally impregnated previous one (see Fig. b).


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For this impregnation use a brush or roller. The woven roving are wrapped around undertension. The resin/hardener mixture will be pressed through the woven roving.

- Using a heater, a heating blanket or to open air the fit layer can be cured. After curing thefitted part can be moved.

- Before continuing grinding again to guarantee a good adhesion between fit-layer andlaminate.

- Laminate resin and hardener should be mixed in a bucket in suitable quantities and the

ground and cleaned surface should be wetted, using a brush or lamb's fleece roller.

- Then 4 layer woven roving of 350 gr./m should be wrapped around the wetted surface in one

time with an overlap of 50%. The woven roving will be tensioned. The resin presses out of

the underlying layers.

For impregnation of the applied woven roving use a roller or brush (see fig. C).

- For diameters up to 100 mm the butt and strap joint is totally built up from woven roving 350gr./m. The thickness of the lamination should be 1,5 the wall thickness of the pipe to be

laminated.

- For diameters 150 mm and upwards the woven roving shall be changed after 4 layers of 350

gr./m in to 580 gr/m, which will be applied in 4 layers with 50% overlap. The last appliedlayer should be well impregnated.

- If the required wall thickness is obtained a final layer of 2 layers woven roving 350 gr./mshould be placed with 50% overlap.

- If the required wall thickness of 1,5 the wall thickness of the pipe is not yet obtained, one

layer of 350 gr./m woven roving will be placed with 50% overlap and then continue with anew package of 4 layers 580 gr./m woving roving with 50% overlap. This cycle shall berepeated until the required wall thickness is obtained (see fig. 6).

- After the final 2 layers of 350 gr./m woven roving have been applied the laminate should be

finished with 2 layers of reinforced non-woven wrapped over the laminate with 50% overlap.

- The superfluous resin should be cured removed using a rubber plate, after which the laminate

should be according to the instructions.

- After the lamination is cooled the joint is ready for use.

NOTE: Other lay-up instruction procedures are also available. Specific work instructions can

be recommended by the manufacturer for specific applications.


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Fig. A

Grinding length L

ID until 50 mm : L = 1,2 x ID

ID 80 mm thru 300 mm : L = 0,8 x ID

ID 350 mm thru 1200 mm : L =

0,5 x ID

grinder surface

30-45

LMax. 5 mm

2-3 mm

Fig. B 5 mm4 layers of woven roving 280 gr/m

impregnated with resin.

Fig. C 4 layers of woven roving 350 gr / m2

Fig. D 8+=u=10t

1.5 +

t

Laminate structure

- 4 layers 280 gr / m2

or 4 layers 270 gr / m2





closing layer

- 2 layers reinforced non-woven

repeated till required thickness

is obtained.


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8.0 Tapping Procedure

8.1 Scope

This procedure outlines the tapping procedure to be used with Fiberglass pipe.

8.2 Tapping Water Pipelines under Pressure

a) The surface of the exposed main pipe where the tapping is to be done should be clean. An

approved flexible gunmetal tapping saddle should be placed at the designated place.

Usually these saddles are two half circles connected with bolts. The minimum distancebetween two saddles is 500 mm and the maximum torque on the bolts should not exceed 10

N.M.

As a standard, the diameter of the outlet will vary from 2 to 4 inches. However other sizesare also available.

b) Tapping machines vary from one manufacturer to another. Below is a generaldescription of the tapping method.

b.1 Screw the maincock into the saddle after removing the plug.

b.2 Install the hole-cutting tool into the tapping machine. The tool should belongenough to cut through out the pipe.

b.3 Start drilling. These machines could be operated manually, pneumatically orelectrically.

b.4 The drill is then raised and the plug closed.

b.5 Unscrew the drilling machine.

8.3 Saddle Material

Any flexible gunmetal tapping saddles can be used. Plastic saddles (polyethylene type) are alsorecommended.

maintenance manual rev 3(repair)

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