This Procedure defines the work method for Installation and lamination of GRP Pipe for the project. The purpose of this procedure is to set out the requirements and methods for Installation of GRP Pipeline including the lamination in detail.
This procedure shall be in compliance with the contract and technical specification implemented on the pipeline project.
This document is based on the Project Specification, Standard and Contractor’s corporate and project procedures and fundamentally incorporates the requirements as noted in the following project Documents.
Specification & Standards for Glass Fiber Reinforced Plastic Pipe (GRP) (For Seawater Pipe), for service other than Sea Water system, ITP for Piping Work, earthwork, grp pipe & Pipe Fittings, Water Distribution Systems, Valves & Expansion joints for sea water service, Condenser & Accessories and flow meters (Seawater system).
Roles & Responsibilities
Site Manager
He shall be responsible for implement the company safety plan overall, and follows;
– To ensure efficient execution of works in accordance with project specifications.
– To arrange necessary equipments from other sites through top management.
– To arrange necessary manpower required for planned work with along term view.
– To manage weekly internal coordination meeting for effective monitoring.
– To encourage the work force for good site keeping.
– To trace the troubles which hurdle the progress of the project and shooting the same with necessary coordination as fast as possible to avoid time loss.
Discipline Manager
He shall be responsible;
– To organize the available resources in the site effectively
– To report to the Site manager or higher management about the resources requirement
– To encourage the work force for the safe and productive working culture
– To deal with the site supervisor for executing earth work in correct procedure at site.
– To coordinate with equipment controller for routine maintenance as well in case of breakdown issues in order to avoid the time delay in the progress of the project.
Site QC Manager
He shall be responsible for the overall Quality control of all the construction activities at site, and follows;
– for managing all the necessary inspections, inclusive of witnessing, recording and reporting the results.
– To ensure that all inspections are executed efficiently and expeditiously in order to comply with the master construction schedule.
– To ensure the preparation of Inspection & Test Plan as per Project specification requirement
– To obtain the approval for the same
– To follow up with Planning section/ construction section for method statement for critical activity
– To execute and monitor the approved Inspection and Test Plan & Procedures for effective results of the product
– To initiate the identification of training & recommending the same to the higher management for the team.
– To initiate the approval of 3rd party Lab approval and coordination for the same as and when required
GRP Pipe Erection Manager
– He shall be responsible for the GRP piping from material handling, Unloading & material storage
– He shall prepare work execution plan for erection, hydro test & backfilling
– Preparation of all documents related to GRP pipe work.
– Preparation of Test packages according to P & ID, Piping Instrument Diagram, piping ISO drawings and Sketches
– Working with project personnel, resolve technical problems which require engineering expertise
– To ensure that all materials and equipments are within the correct specification prior to installation.
– Review and correction of hydro test packages for correct system names type of test and other relevant data.
– Responsibility to monitor the daily activities on site and evaluate workers.
– Performance to insure that the progress of works is in line with the schedule.
Site HSE Manager
He shall be responsible for the overall safety of personnel materials and equipment during the construction and pre-commissioning of a Project, and follows;
– Ensure all the operations at the site are conducted to the minimum safety standards, and that they are maintained throughout construction.
– Coordinate and preside over regular site safety meetings, to attain and maintain effective communications, between Sub Contractor, Contractor and Company’s personnel.
– Establish policies and procedures for the Sub-contractor Site personnel
– Monitors the removal of physical, biological and chemical hazards, and training of employees on safety policies, procedures, and regulations. Verifies compliance with health and safety regulations and ensures all necessary records are maintained and prepared according to established guidelines.
– Manages the participation in Occupational Safety and Health Administration (OSHA) inspections, providing inspectors with appropriate documents and identifying safety measures.
– Ensures projects are completed on time and within budget. Acts as adviser to health and safety administration team regarding projects, tasks, and operations.
Site Supervisor
Periodic visits to the job site throughout the duration of pipe installation to advise the contractor on the proper and applicable grp pipe handling, storage, laying, jointing and site testing procedures necessary to achieve a satisfactory pipe installation.
Delivery Handling & Storage of GRP Pipes
Prior to unloading of pipes from trailers, all items shall be inspected for any visual/transportation damages.
Single pipes must be unloaded and handled separately (one at a time). Use pliable straps, slings or ropes to lift single pipes.
Do not use steel cables or chains to lift or transport the pipe.
Care shall be taken to prevent pipes from rolling or falling from flat bed trailer and this shall be attained by using proper supports.
If at any time during handling or installation of the pipe, any damage such as cracks, de-lamination or fracture occurs, the pipe should be repaired before the section is installed. Contact grp pipe supplier for inspection of damage and for recommendation for repair method or the replacement.
The rubber gaskets received along with the pipes and fittings shall be stored in shelter with original packing until it is used at site.
The gaskets must be protected from exposures to grease or oils, which are petroleum derivatives, and from solvents and other deleterious substances.
Handling of nested pipes:
Loading Pipes, fittings and prefabricated parts (spools) have to be transported by suitable trucks.
These trucks must have flat floors. Check for and remove any projections or nails etc. before each load.Materials must be secured for example by using wedges and wooden supports.
These supports must have a minimum width of 10 cm, avoiding sharp edges. Usually the materials are tied in place, using pliable nylon or canvas slings. Chains or steel cables may not be used under any circumstances.
The support distances must not exceed 2.5 meter. The width of the supports must be a minimum of 10 cm. When grp pipes are inserted (one inside the other), the support distance shall not exceed 2 meter. Flanges must be secured against sliding. Flanges may only be loaded on their sealing face if they are sufficiently protected against damage.
The best way for fittings to be transported is in crates or onto pallets. Direct contact between products during transport must be avoided. Pipe ends and machined parts must be protected, for example, by means of straw mats covered by polyethylene sheet or polyethylene netting.
Pipes and spools should be lifted by using nylon or canvas hoisting belts with a minimum width of 10 cm and must be lifted at two points, using the largest diameter of the prefabricated part (spool), in such a way that the weight is well-balanced.Any part of the truck has to be protected by wood or rubber wherever in contact with the products.We recommend the use of trucks
which can be loaded from the sides. If pipes are handled by a forklift truck, the forks must be covered with rubber or plastic
DO NOT LIFT THE GRP PIPE BY PASSING A ROPE THROUGH THE SECTION END TO END.
Transporting the GRP Pipe
If it is necessary to transport pipes at the job site, it is best to use the original shipping dunning when loading the truck. If this material is no longer available, support all pipe sections on flat timbers spaced on a maximum of 10 feet centers with a maximum overhang of 5 feet. Chock the grp pipe to maintain stability and separation.
Ensure no pipes contact other pipes, so vibrations during transport will not cause abrasion.
Strap pipe to the vehicle over the support points using pliable straps or rope – never use steel cables or chains without adequate padding to protect the pipe from abrasion. Bulges, flat areas or other abrupt changes of curvature are not permitted. Transport of pipes outside of these limitations may result in damage to the pipes.
GRP Pipe Unloading
The unloading of material is the responsibility of the client, unless agreed otherwise.
Because of the relative lightness of glass fiber reinforced plastics (approximately a quarter compared to steel) handlers may be tempted to handle it roughly, or unload it by letting it drop of its own accord. This may cause serious damage to the material and therefore material should be handled with care.
Do not use chains, steel cables or clamps during lifting. Nylon or canvas hoisting belts with a minimum width of 10 cm must be used. Standard pipe lengths must be picked up at two supporting points. Ensure that hoisting belts are always put round the widest part.
We strongly recommend that the pipes are unloaded one at a time when hoist belt used. Each consignment is carefully loaded and must be inspected on site in order to ensure that no damage has occurred during transportation. This will avoid disputes with regards to responsibilities.
Storage of GRP Pipe materials
In order to avoid damage to the stacked pipes, the following rules are important:
a) Do not lay the pipes directly on the ground, onto rails or concrete floors. Provide a flat surface.
b) Ensure suitable supports are used for example wooden beams, measuring 10 x 5 cm to avoid damage to machined pipe ends, stacking should be undertaken with care.
c) The machined ends must be protected for example by polyethylene covered straw mats or polyethylene netting.
d) The socket and spigot ends must not touch each other.
e) The pipes can be stacked economically by alternating the spigot and the socket, as illustrated below. In order to avoid bending of the pipes, the beams should be laid directly above each other in a vertical line. Supports should be spaced at a max. of 3 meter intervals and about 1 metre from each end. The width of the supports should be at least 10 cm. The maximum allowable stack height is 1.5 meters. However, for diameters of 800 mm and above, a maximum of 2 pipes may be stacked one on top of the other. If the product is stacked too high for long storage periods (6-12
months) and subjected to high temperatures, the supports may cause flattening. It is recommended that the product (in particular machined parts) is stored under tarpaulins or (white) polyethylene sheeting. Pipe stacks should have side supports or blocks to prevent rolling or slipping of the stack during stormy weather.
f) If any damage during transportation or installation is noticed such as scratches, cracks or pits, Future Pipe Industries should be contacted for any repair or replacement. Never use any damaged material.
Installation Method of GRP Pipes
A.Excavate all material of whatever nature encountered to the lines and grades as shown.
1). Excavation includes removal and disposal of pavements and other obstructions on ground surface, underground structures and utilities indicated to be demolished and removed, and all other materials encountered.
Please go through the method of statement of excavation of earth work for more technical details. If applicable do the dewatering of the excavations.
HOT WEATHER WORK
The gel time decreases as the air temperature increases. In certain situation, this property is beneficial in particular in hot climates. When working in direct sunlight above 40°C, the work area should be shaded with a sun screen to allow uniform working time and curing of the lay-up around the pipe
EXTERIOR LAY-UP
GRP Vendor’s Authorized person will be witnessing the first 2 joints to ensure the work in accordance with standard.
- Grind the outer surface of the pipe as per the required minimum bond length mentioned in the provided field recipe. Extend the sanding of the bond length 20 mm more than the required length to ensure complete bonding of the lamination material is achieved over the minimum specified bond area.
- The maximum time between the grinding operation & lamination process is two hours. In case of delay in starting the lamination operation, the entire sanding operation has to be redone.
- After the component resin/hardener is thoroughly mixed one can start the fit procedure.
- The cross section of the pipe has to be protected against penetrating liquid using a resin or adhesive layer.
- After the pipe sections are positioned they should be wetted over a length of approx. 5 cm on both sides of the “weld” using resin/hardener, mixtures, after which the fit layer can be made.
- Wrap 5 layers of 270 gr/m² 5 cm width for dia 25 through 350 mm and for dia 400 through 2000mm 5 layers 270 gr/m² 10 cm width have woven roving around the “weld” taking care that every following layer applied over a totally impregnated previous one. For this impregnation use a brush or roller. The woven rovings are wrapped around under tension. The resin/hardener Mixture will be pressed through the woven roving.
- Be sure to cure the fit layer over the entire circumference. After curing the fitted part can be moved. In large diameter the fit layer thickness should be increased if the part has to be moved.
H. Before continuing, grind again to guarantee a good adhesion between fit layer and laminate. - After the fit layer has hardened re grind the entire tapered section of the pipe & fill it with pieces of 360 gm woven roving & resin mix until the entire tapered portion is filled in level with the outside diameter of the pipe. Allow the laminate to cure at ambient temperature. This is done to avoid excessive exothermal heat that may interfere during the final welding operation.
- When the above laminate has hardened sufficiently the exterior part of the laminated area as well as the total required bond area should be sanded well for the final welding process.
K. Laminate resin and hardener should be mixed in a bucket in suitable quantities by preference mechanically e.g. using a propeller mounted on a drilling machine or manually using a spatula for approx 1 min. The woven roving must be wrapped with an overlap of 50%; this means that 2 layers per winding are generated. The abraded and cleaned surface should be wetted with resin mix, using a brush or lamb’s wool roller. - Then layers of woven roving should be wrapped around wetted surface. Each applied layer must be thoroughly impregnated. The woven roving requires to be tensioned, so the resin presses out of the underlying layers. For the impregnation of the applied woven roving use a roller or brush.
- For diameters up to 150 mm the butt and wrap joint is totally built up from woven roving’s 270 gr/m²; for dia m 25 through 50 mm the width will be 5 cm, for dia m 80 through 150 mm the width will be 10 cm.
- Diameter range 200 mm through 350 mm the butt and wrap joint is totally built up from woven roving 360 gr/m² 10 cm width. The thickness of the lamination must be maintained at 0.75 x the bond area at either end of the joint. For detail of bond area & thickness, please see the required lamination recipe.
- For diameters 400 mm and above the woven roving shall be changed after 12 layers of 360 gr/m² 10/16 cm width into 580 gr/m² 10/16 cm width, which will be applied in 4 layers alternated with 2 layers of 360 gm layers. The first 12 layers (6 double) should always be woven layers of 360 gm.
- For diameter range 700 mm through 2000 mm lamination has to be started using woven roving of 360 gr/m² 16 cm widths.
- When the required wall thickness is obtained a final layer of 2 layers of woven roving for diam > 350 mm 360 gr/m² 16 cm width should be applied. R. After the 2 final layers of 360 gr/m² 16 cm width woven roving have been applied, the laminate should be finished with 2 layers of reinforced non-woven wrapped over the laminate.
- The superfluous resin should be removed using a rubber scraper plate after which the laminate should be cured at room temperature.
Note: For larger diameters it may not be possible to complete the entire lamination process in one go. Therefore the lamination process has to be interrupted in case gelation occurs. The laminate should be allowed to cure at room temperature & later regrind to continue the rest of the welding process until the required thickness has been achieved. The exact quantity of the material of the butt strap joint shall be issued by Engineering department for each diameter and pressure.
Further Recommendations
Adjacent pipes should not have different self deflections causing joint steps, but where a pipe butts up against a fitting of different thickness, a slight difference in roundness may occur with the pipe being deflected more than the fitting. It is possible to correct this slight out-of roundness on the pipe by using a jacking prop with wooden load spreaders at each end.
Where different thicknesses of adjacent parts are encountered (e.g. pipe to reducer, pipe to elbow, or pipe to tee), the parts should be aligned concentrically and any step greater than 6 mm removed by applying a 15 deg. tapered build up to the grp pipe surface with glass mat and resin. This should be applied all round the pipe and rolled out as normal. Steps less than 6 mm can be tapered off with resin/cabosil putty or filled with woven roving. The lay up joint can then be applied in the normal manner.
It is important that when pipe surfaces to be laid up are cleaned with solvent, the solvent must be freshly drawn and clean. The cloths should also be clean, made out of white cotton. The solvent used for this cleaning operating can subsequently be used for cleaning rollers, tools, gloves, etc.
Precautionary Measures for GRP Pipe Installation Works
Do not use resin that is gelling (beginning to thicken). The lay-up cannot obtain full bond strength with gelling resin.
Ensure all solvent used to clean the pipe has completely evaporated before applying the layup. The lay-up loses its bond if it is applied on a surface with solvent on it.
Never allow solvent to run on uncured resin.
If the lay-up is not properly bonded to the grp pipe, remove the lay-up and wash the area with solvent, being careful not to run solvent into uncured lay-up areas.
During a period of rapidly changing temperature, pipes may move due to expansion or contraction. This movement could reduce the bond strength of the initial lay-up plies, if the plies have not cured prior to the movement. If this phenomenon is experienced, the pipes must be restrained against movement while the lay-up joint is being fabricated.
When working on the bottom side of the joint, a faster gel time is desired. This can be accomplished by (1) increasing the amount of catalyst (2½% maximum) and / or (2) using the heat of a previous lay-up. Remember never place a lay-up over another lay-up, if the first one is not comfortable to touch with the bare hand.
In the event that a lay-up joint is not completed on the day it is started or if a layer of the lay up is allowed to cool for several hours, the following procedure should be followed:
a. Remove the glossy surface of the lay-up by grinding the lay-up area covered by resin.
b. Wipe the ground area with clean solvent to remove collected dust and allow the solvent evaporate completely.
c. Continue to apply the remaining layers of the lay-up as previously described.
Note: If the top layer of mat is removed when grinding, it will be necessary to apply an additional piece of mat when the final layer of the lay-up is applied.
Internal Sealing Joint
GRP pipe Vendor’s Authorized person will be witnessing the first 2 joints to ensure the work in accordance with standard. Grind the area to be bonded preferably just prior to the welding process.
Ensure that any gaps between the pipes are filled well with Cabosil/resin mixture or glass roving’s.
Apply the given nos. of 270 gm woven roving with the resin mixture until the required thickness has been achieved. In cases where gelling occurs discontinue the lamination process & allow to cure at room temperature. Re grind the areas after the curing process is completed & continue the lamination process until required thickness has been achieved.
Finish the interior layer with one layers of C glass & resin mixture.
See lamination recipe for detailed bond area & layers. Slightly different procedures and safety measures must be observed when making internal lay-up joints. Make sure proper ventilation is available when working in close environments. Wear safety masks & goggles always when in contact with chemicals.
Curing & Finishing of GRP Lamination
The resin/catalyst system is as illustrated in below table; the curing curve was obtained in ambient temperature of 20oC and relative humidity of 75%. Adjustments are required to suit local temperature and humidity; good judgment should be exercised.
After well mixing the above and before start the lamination process add 150 g catalyst to each 1 Kg of the above mixture.
The resin, catalyst, booster and accelerator used in performing the lamination are flammable and can cause harm if not used properly. Data sheets of each material should be obtained from supplier and read carefully prior to commencing work. The following list shows equipment that must be supplied by the installation or lamination contractor:
– Rotary disc sander
– Carborundum sanding disc 16 grit
– Polyethylene pots for mixing resin with 1 gallon capacity
– 1 Pint graduated cylinder for measuring catalyst
– Paint rollers 5 cm diameter and 15 to 20 cm long
– Wooden spatulas for mixing resin & catalyst
– Masking tape
Quality Control
There is no specific standard for conducting visual testing. Basically the lamination should not have irregularities in shape and appearance.
Dimensional: The thickness and width of each joint is given in the process sheets. Those are the minimum values.
Lamination works to be done by skilled operators, trained and qualified by manufacturer.
The following material shall be prepared;
– Fiberglass joint kit which includes:
– Fiberglass Woven Roving with specific dimensions as per diameter.
– Vinyl Ester Resin (promoted, not catalyzed)
– Top tape for the top coat of the joint
– Catalyst /Hardener
– Cabosil powder
– Styrene
– Inhibitors
Site Material Storage
– Resin – Shall be stored in shelter.
– Catalyst- shall be stored in a properly regulated store temperature of 20°C to25°C.
– Fiberglass kits woven roving – shall be stored in a close room to avoid dust, dump and direct sunlight.
– Styrene – shall be stored in shelter.
Marking
Each grp pipe/fitting and spool shall be permanently marked with following information:
a) Manufacturer‟s name or initials and identification code
b) Normal size
c) Pressure rating and temperature rating
d) Number and date of selected code
e) Resin and reinforcement type
Upon satisfactory completion of inspection and testing on pipes, fittings and spools, the organizations responsible for design, construction and inspection shall furnish copies of the certificate to the Purchaser, stating the design, construction and testing complies with this specification and selected code.
Quality assurance / documentation
QA shall be according to requirements in selected codes and manufacturer‟s QA manual approved by Purchaser / Owner.
Detailed design drawings shall be prepared by the Vendor and submitted for Purchaser approval prior to start of manufacturing. All important construction details must be shown in details-drawings.
Certification
The Manufacturer shall provide quality control test reports. Manufacture shall submit a certified record of inspection and testing together with a statement of compliance with the requirements. These shall also include the relevant certificates for metallic parts, if any.
Additionally, requirements of Owner in regards certification stipulated in his specification shall be met. The installed pipe lines shall be hydro-tested
Personal Protective Equipment (PPE)
– Coveralls
– Hard hat
– Safety boots
– Gloves(rubber and cotton)
– Safety glass
– Paper mask
– Respirator with cartridge (RC202) filters (for internal lamination works)
– Full body harness(working at height)
– Face shield to use during the grinding works.
– Access to suitable fire extinguishers tor internal and external work faces.
– Eye wash tools on vicinity of the working area (during the lamination work)
Hazard Identification and Risk Assessment Worksheet
Equipment mobilization Crane, Boom truck, System including pump, Trailer Truck, Hand tools, Lamination Kits and Accessories
Control Measures
– Crane must have current 3rd party inspection.
– Crane operators and drivers must have current SAG license and TUV certificate.
– Appropriate documents to be sent along with the equipment.
– Documented pre-deployment maintenance check of the equipment by mechanic.
– Crane load chart and operating manual available.
– Hand signals posted on the crane.
– Must pass – Inspection.
– Monthly equipment inspection & color coding.
– Conduct daily inspection using equipment daily inspection checklist.
– Through inspection of all equipment shall be carried out by a competent person designated by ESD-Equipment Service Department prior to delivery of the equipment to the project.
– Fire extinguisher shall be provided on every equipment with internal combustion engine, 20lbs.
– Obtain necessary work permit
– As built underground drawing and plot plan from MET showing buried facilities and limitation shall be provided.
Working in a confined space (for excavation 1.2 m and deeper)
– Obtain necessary work permit, no confined space entry starts without a dedicated trained entry attendant physically available at the entry point. The entry attendant remains outside the space to constantly monitor (by visual or auditory communication) authorized entrants working inside the space.
– Ensure gas testing is performed in every level prior to entry.
– Ensure rescue equipments are available.
– Entry attendant shall maintain al log to fully account personnel inside the space.
– The space must be evacuated in emergency inside/outside space or hazardous atmosphere is detected.
Scaffolding Erection over the GRP Pipe field joints
– Selecting right scaffold for job.
– Assigning personal and training.
– Scaffold inspection and tagging
– Scaffolding materials proper maintenance and storage.
– Compliance with PPE requirements use eye/face protection, hand gloves, hard hats and safety shoes.
– All tools/rigging devices to be used will be checked/inspected and color-coded by competent inspectors.
Pipe Installation
– Obtain necessary work permit.
– Sequence of work shall be discussed during daily toolbox meeting before work commence.
– Lifting plan to be discussed by rigging supervisor along side with crane operator, riggers, assist crew, etc.
– Only competent person shall perform all rigging works.
– Lifting gears/tackles shall be inspected prior to use.
– Use proper length and size of slings and ensure lifting tackles in good condition.
– Softeners to be used to protect sling from sharp edges.
– Two tag lines shall be used to control the load.
– Crane shall be properly set-up and appropriate timber pads to be used.
– Physical barricade to install and maintain with entry and exit points.
– “Danger lifting on progress, keep out” signboards to be posted.
– No erection allowed during harsh weather e.g. wig exceeding 20mph, thick fog, heavy sandstorm, rain.etc.
Fit-up and Lamination of joints
Lamination joint on GRP piping has two stages:
a) Grinding the pipe surfaces (internal, external).
b) Application of the layers.
c) Witness and approval of Fit-up should be done by the QC Inspector prior to lamination.
External Lamination
Fit Layer
a. Measure the fit layer bond length from the end of each grp pipe.
b. Grind the above area to remove the topcoat and surface layer of the pipes until the pipes glass fiber are exposed.
c. Clean this area by dry clean cloth or paintbrush and ensure that it is fully dry.
d. Fill the gap if any between the two pipes with cab-o-seal putty.
e. Mix the resin and hardener as per the quantities specified in the recipe to maintain the right ration.
f. Impregnate the roughened area with above mixture.
g. Apply woven roving glass 270 using a 50% overlap between each two consecutive windings so that wrapping the full surface will end up with two layers of glass.
h. Impregnate the above layers with the resin/hardener mixture.
i. Repeat the above two steps till the required number of layers is applied.
j. Wait till the lamination is cured under ambient temperature. The curing time of the fit layer ranges between 1 to 2 hours depending on the sunlight.
Main Laminate
a. Measure the bond length on each grp pipe from the middle of the fit layer.
b. Grind the above area to remove the topcoat and surface of the pipe until the pipe glass fiber are exposed.
c. Clean this area by dry clean cloth or paintbrush and ensure that it is fully dry.
d. Mix the resin and hardener as per the quantities specified in the recipe to maintain the right ration.
e. Impregnate the above layer with the resin/hardener mixture.
f. Apply woven roving glass 270 using 50% overlap between each two consecutive windings so that wrapping the full surface will end up with two layers of glass.
g. Impregnate the above layer with the resin/hardener mixture.
h. Repeat the above two steps till the required number of layers is applied.
i. Depending on the pipe diameter and pressure class, the type of glass and the number of layers are specified in the lamination recipe. If only glass 270 should be used, skip all the below steps except the last one to end up the lamination with two layers of top tape. Otherwise move the next step.
j. Apply woven roving glass 360 using 50% overlap between each two consecutive windings so that wrapping the full surface will end up with two layers of glass.
k. Impregnate the above layer with the resin/hardener mixture.
l. Repeat the above two steps till the required number of layers is applied. A maximum of 12 layers should be applied at this stage as “initial winding”.
m. If more should be applied, move to the following steps. Otherwise skip all the below steps except the last one to end up the lamination with two layers of Top Tape.
n. Apply the specified number of layers of woven roving 580 and 360 alternatively. Each type of glass should be applied in four consecutive layers before changing to the other type. Every two layers should be impregnated before applying the second two layers of the same type.
o. Apply two “sealing layers” of woven roving glass 360.
p. Impregnate the above layers with the resin/hardener mixture.
q. Wind two layers of top tape glass around the laminate to extract the excess quantity of resin and to provide smooth surface.
r. The lamination is cured under ambient temperature. Make sure that the joint is undistributed until it cures. The curing time varies between 4 to 8 hours depending on the sunlight exposure and temperature.
Internal Lamination
(Applicable only for 900mm & above in condition that the access to the joint internal area is safe and possible).
The following steps are to be done inside the pipes:
1. Measure a length of 50 mm from the end of each grp pipe.
2. Grind the above area to remove the internal liner of the pipe.
3. Cut several pieces of woven roving glass 270/100 with equal length.
4. Mix the right quantity of resin and hardener.
5. Wet the surface area of internal layer with mixture.
6. Stack several pieces of woven roving on a flat surface and impregnate with the resin mixture.
7. Place the above impregnate woven roving on the joint.
8. Evenly press the surface to flush air traps and blisters using steel roller.
9. Repeat the above three steps until the required thickness is reached.
10. Cover the above laminate with two layers of C glass surface veil material (surface mat) to provide a smooth resin-rich laminate surface.
11. The lamination is cured under ambient temperature.
For internal lamination, the plies edges shall be penetrated into the previously made grooves at both side of the lamination width to maintain smooth flow of the product during operation
Precautions
a. The prepared bond surface area should be free from grease, oil, dust, moisture, water, etc. Clean the surface using a clean and dry cloth or a dust brush.
b. Do not move the joint before the laminate is cured.
c. Lamination should be stopped in case resin starts gelling. To continue the laminate, surface should be abraded.
d. Safety precaution for internal lamination as follows:
Internal lamination shall be done immediately after completing the external lamination to limit the entry distance to a standard grp pipe length. When this is not possible, i.e., where the entry distance is longer than 20 meters the following safety measures shall apply:
- If required, the client safety personnel to measure concentration of any toxic gas and oxygen inside the pipe before giving clearance to enter the line.
- Use personal protective equipment before entering the pipe.
- If required, use a rechargeable lamp or hand torch for enough light inside the pipeline. Usually, the daylight is sufficient at the 1st joint near the open end.
- Ensure that no blockage at the access of the open pipe end.
- Use exhaust fan or blower to ensure fume free and to avoid accumulated fumes.
- Ensure that there is no water present in the line/sections, other wise use dewatering pump and sand bags to prevent flow of water to the joint to be laminated.
- If required, a watchman should be standing outside the pipe and in frequent verbal contact with the technician working inside the pipeline.
- If the internal joint to be carried out is more than five standard pipe away, a rope will be tightened from the waist of the technician for easy pull out inside the pipe and to ensure his safety in case something gets wrong inside the pipe.
- The chemicals are potentially flammable, NO SMOKING inside the grp pipe is allowed and in all areas where lay ups are being made.
- If required, technicians will wear fume mask to protect from fumes and chemical smell.
- A safety guards shall be mounted on the grinders.
- Follow any safety rules as strictly enforced of the end users and the client.
Repairing of Lamination Joint
If any lamination joint is found to be leaking cut the joint out and replace it with a pipe piece. Connect this piece by two laminations following the same procedure described above.The same shall be done if the leak occurs on the pipe wall due to impact damage.
If possible, the leaking lamination can be removed by grinding it off the pipe completely and re-laminate by a new one following the same procedure described above.
In case of a superficial damage on the pipe, the following steps to be followed. A superficial damage is a scratch within the resin rich outer layer of the pipe.
- Abrade the damaged area by using emery paper.
- Use a brush to clean the area from dust.
- Mix the resin according to the recipe.
- If it is necessary apply 1 or 2 layers of C-glass.
- Apply the mixed resin on the damaged surface.
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