Pipe systems for hydro-power plants
“Poliester Grupa” as a company has due to long tradition in processing and utilisation of polyester, particularly production of GRP pipes, and collaboration with world most famous international companies from this area, gained enormous experience and knowledge. Reference list of projects proves this.
01.
Production process Polyester pipe is manufactured of unsaturated polyester resin reinforced with glass fibre with addition of additives and fillers. Usual name for these pipes is GRP pipes or fibreglass pipes. By different combinations of glass fibre, polyester resin and filler, it is possible to acquire a pipe with big span of mechanical and physical-chemical characteristics, a pipe capable to comply with a wide spectrum of operation requirements. Production procedure for manufacturing of these pipes is continuous; it is possible to acquire a pipe of different lengths, and production process uses a combination of choppable and continuous glass fibre which give a high performance qualities to the pipes. Fibreglass composite technology enables polyester pipe to be successfully compared with pipes of traditional materials, concerning longevity – price ratio, which represents a base for performance qualities. Since fibreglass composites provide such an extraordinary combination of properties enabled by ratio price/performances, the number and kind of products manufactured efficiently, effectively and in a good quality of composite materials, increases each year. Composites reinforced by glass fibre have proved it's qualities in a pipelines made in a cold environment of Alaska, under hot sun of Arabic desert, in chemically aggressive environment of Mexico golf and in a beauty of the latest car models. These composites can be accommodated to any of these circumstances, and even more, because a combination of thermo-active resin, glass fibre and suitable process, gives a product far more worth than a pure sum of it's components.
protecting glass fibre foil
roving flow glass fibre saw sand and chopped roving
engine drive
Graphic outline of pipe production process
polymerisation
C glass computer and control display
finished pipe dosage pumps
day containers
02.
Pipe wall structure
Layer
Construction
Purpose
Inner layer
"C" glass
Protection
Border layer
Chopped glass fibre
Protection
Inner structure layer
Continuous glass fibre and chopped glass fibre
High coefficient of structure reinforcements
Core
Silica sand and chopped glass fibre
Durable - hard core
Outer structure layer
Continuous glass fibre and chopped glass fibre
High coefficient of structure reinforcements
Outer layer
"C" glass
Protection
Note: Resin is implied in each layer
Outer layer Outer structure layer
Pipe wall structure Core
Inner structure layer Border layer Inner layer
03.
Advantages of the product: Long and efficient operating life Costly cathode protection is not necessary Costly lining, coating and painting are not necessary Law maintenance costs Hydraulic properties remain unchanged for a long period Withhold properties both in very hot and cold climate Low weight (1/4 of cast iron pipe weight or 1/10 of concrete weight) which facilitates installation on heavy grounds Extraordinary wall sleekness Water hammer pressure approximately 50% lower compared to still and cast iron under the same circumstances Produced in long pipe sections Double muff joints with rubber gaskets are produced of reinforced polyester Pipe specifications comply with world wide standards Production is based on advanced technology Easy to install. Expensive installation equipment is unnecessary. Transportation costs are low. Minimal silt precipitation contributes to very low maintenance cost Lower number of joint points decreases installation time. Easy joining – shorter installation time. Non-permeable and efficient couplings are constructed to eliminate infiltration and leakage. Joining connections are not necessary. Enables flexible changes of pipeline axes. Enables high quality specification of the product. Permanent quality ensured for all purposes. UV Stability provided.
Physical – chemical characteristics Density .................................................................................................................................................................................... (1800-2100) kg/m3 Elasticity module ............................................................................................................................................................................... (6 -24 )GPa Circumferential elasticity module – tensile and bending ................................................... 17 000 MPa – low pressure pipes 24 000 MPa – high pressure pipes Elasticity module longitudinal - tensile and bending ..................................................................................... (6000-12 500) MPa Tensile strength circumferential ............................................................................................................................................ (130-700) MPa Tensile strength axial ..................................................................................................................................................................... (30-60) MPa Bending strength circumferential ........................................................................................................................................... 140-500 MPa Elongation to break ................................................................................................................................................................................ 1,5-2,0 % Linear spreading coefficient ................................................................................................................................................ 24-30·10 -6 1/°K Max. temperature of transported media ............................................................................................................................................. 50 °C Temperature conductibility coefficient ............................................................................................................................ 0,14-0,25 W/mK
Hydraulic characteristics Absolute hoarseness .................................................................................................................................................................. “ k“ = 0,012 mm Hazen Villiams constant .................................................................................................................................................................... “ C“ = 150 Manning constant ............................................................................................................................................................... “ n“ = 0,0095-0,012
04.
Standards Here is review of standards applied for production, testing and quality verification of polyester pipes.
1. STANDARDS FOR CONTROL AND TESTING OF RAW MATERIALS Standards for control and testing of resin quality 1. ISO 2555 - viscosity testing 2. ISO 25353 - gel time testing 3. ISO 2811 - density testing 4. ISO 3251- Styrene content determination 5. ISO 2114 /-Acid number determination 6.ISO 584 / Resin reactivity.
Standards for control and testing of reinforcement fibre 1.ISO 1889- Linear density determination (tex) 2.ISO 3344- Moister content determination 3. ISO 1887 - Loss on ignition 4. ISO 3268- (OC R110) Tensile strength and reduction factor 5.ISO 2078 -Glass type 6. SNO5320- Resin wet out time
Standards for control and testing of silica sand 1.OC R 115/-Carbonate content 2.OC R 114- Moister content 3.OC R 112- Loss on ignition 4.OC R 116- Resin wet out time 5.ASTM E11- Granulation
Standards for control and testing of styrene 1.ASTM D2121 - Polymer content in styrene monomer
Standards for control and testing of methilethilketonperoxide (MEKP) Co octoate 1.ISO 2555 - Viscosity testing 2.ISO 2535 - Ignition time testing 3.OC R111 - water content in MEKP
05.
Standards
2. STANDARDS FOR CONTROL AND TESTING OF PIPES 1.ASTM D3567 2.AWWA C950 3.ASTM D3517 4.ASTM D3754 5.ASTM D3262 6.ASTM D2412 7.ASTM D2583 8.ASTM D 790 9.ASTM D2290 10.ASTM D 638 11.ASTM C 581
Standard procedure for determination of pipe and fitting dimension Standard for high pressure pipes for water supply Standard specification for fibreglass pipes for high pressure Standard specification for fibreglass pipes for sewage and industrial waste water Standard specification for sewage pipes Pipe stiffness and deflection Hardness acc. Barcol Bending properties of plastic materials Circumferential tensile strength Elongation properties of plastic materials Standard procedure for determination of chemical resistance of resin used in structures with reinforcement of glass fibre purposed for transport of liquid 12.ASTM D4161 Standard specification for joints of fibreglass with usage of flexible gaskets of elastomer 13.ASTM D1172 Laminate structure (pipe) 14. ASTM D3839 Standard procedure for underground installation
Production programme Pipe programme Pipe diameters POLIESTER pipes are available in wide spectrum of diameters along with necessary fittings and accessories. POLIESTER pipes can be delivered with following nominal standard diameters DN (mm). Pipe diameters DN (mm) 300
700
1300
1900
350
800
1400
2000
400
900
1500
2100
450
1000
1600
2200
500
1100
1700
2300
600
1200
1800
2400
06.
Pressure classes Pipes are delivered in pressure classes from 1 bar to 32 bar, and it should be underlined that all pipes pressure class over 1 bar are 100% tested on test pressure according to required test standard. Pressure class Designation
Operating pressure
PN
KPa
bar
1
100
1
2,5
250
2,5
6
600
6
10
1000
10
16
1600
16
20
2000
20
25
2500
25
32
3200
32
hydrostatic pressure testing
Stiffness class Pipe stiffness is capability to overtake crown load of ground and traffic, as well as negative inside pressure. POLIESTER pipe are delivered with following tangential initial stiffness (STIS) EI/D3
Stiffness class
stiffness and deflection testing
Designation
Stiffness
SN
Pa
1250
1250
2500
2500
5000
5000
10000
10000
Lengths Standard lengths of polyester pipes are 6 m and 11,8 m. All lengths up to 11,8 m can be delivered.
07.
Fittings and accessories A wide range of GRP fittings and accessories is available along with pipe programme. This includes: bends, branches, flanges, reducers (concentric and non/concentric) e. t .c. Concentric reducers are used for transition from one to another nominal diameter, and are used primary on pressure pipes. High flexibility of material enables manufacturing of individual fittings based on measures on customers requirement.
"T" branch
Bend 1°-90°
Sloping branch
08.
Flange
Reducer
Specificity of products POLIESTER GRP pipe systems enable solutions for applications characterised by high requirements in regard to huge strength of glass fibres and high level of corrosion resistance of resin. Such combination of mechanical and chemical properties make them ideal for small hydro-power plants.
Characteristics of POLIESTER pipe systems in regard to certain features Flow velocity/ hydraulic properties
++
Corrosion resistance
++
Ratio kg/m
++
UV resistance
+
Heat expansion
+
Chemical resistance
+
Thermal insulation
+
Operation life
++
All production processes are certified by third side and company is certified with certificates like ISO:9001 and other. Pipe systems comply with standards of different countries like ASTM, EN, DIN, BSI, ISO, AWWA and many other international and local standards and certificates.
09.
Nominal project testing pressure Very important qualification test of POLIESTER pipe for application on small hydro-power plants is inner pressure of pipeline. Pressure class must be higher or equal to projected working pressure. It is based on pressure value which the pipe is to withstand at the age of 50 years, and is calculated according to equation:
Pressure tension
PN = HDB(50 years) / FS
HDS
Security factor =1.8
PN
Time
50 years
PN – pressure class HDB (50 years) pressure value which the 50 years old pipe will withstands FS – Security factor, taken FS = 1,8 for operating time of 50 years
Simple transportation 10.
Lay ing o f the p ipe
Pressure declination Elevation loss or pressure decline occurs in all pipe systems, because of level changes, shafts, turbulence caused by direction changes and friction inside pipes and fittings. There are many mathematical methods to determine elevation loss in fibreglass pipes. Most often used methods are those by Hazen-Williams, Manning, Darcy-Weisbach. Acceptability of each of them depends on assumptions. All these methods are applied to fibreglass pipes and they imply comparatively smooth internal surface of a pipe. As indicated in the table of hydraulic characteristics, one may say that absolute harshness is 0,012 mm, Hazen/ Williams constant "C"=150, Manning constant "n"=0,0095/0,012, coefficient of linear expansion (24-30) x10 1/°C. It can also be specified that relation between "hoop" load on circumference and axial reaction is around 0,25, while for the opposite case Poisson's coefficient is a bit smaller. Those who deal with pipe installation know for a great while ago that fibreglass pipes have considerably lower friction coefficient than the pipes of carbon steel. It is very important to get to see the importance of lower friction factor in terms of energy saving and price reduction during working life of a system. Greatest savings come from reductions on pumping costs of a system. Energy consumption often falls to a half. POLIESTER fibreglass pipes do not exhibit any corrosion (they do not change with time), compared to other materials which are corrosive, where corrosion directly affects harshness of those pipes. In these pipe lines, it is possible to use velocities up to 4 m/s when the water is clean and do not contain any abrasive material.
11.
Hydraulic shock (water hammer) Inner shock or pressure surge, generally known as hydraulic shock, occurs as a result of abrupt change of fluid velocity within a system. Passing pressure is a wave which is moving very fast increasing and decreasing pressure in the systems, depending on origin of flow and direction of wave movement. Sudden closure of the valve can cause the shock wave, by transferring kinetic energy of moving fluid into potential energy which has to be distributed. Sudden outlet of the air and setting on and off the pumps can cause shock wave. The size of hydraulic shock is a function of fluid properties and velocity, elasticity module of pipe material, length of the line and change of velocity in fluid quantity movement. Accordingly high compliance (low elasticity module) in fibreglass pipes contributes the effect of self-suppressing as pressure wave moves along pipe system. In fibreglass pipes hydraulic shock is approximately 50% of that in for steel pipe systems under similar conditions. POLIESTER fibreglass pipes according to standard applied, allow pressure waves up to 40% of nominal pressure.
UV stability of the pipe All pipelines of fibreglass are subjected to changes when exposed to sun light. This is superficial phenomena caused by degradation of resin due to ultraviolet radiation. Appearance change rate depends on intensity of sun light and the exposure time. If the resin is heavily degraded on surface, quality is spoiled, glass fibres become visible. They prevent further degradation by absorbing ultraviolet radiation with no damage. Superficial degradation (deterioration of surface quality) has very small influence on operational properties of pipeline system. Prevention or control over atmospheric influence on surface can be attained by painting with paint of quality solvent. Paint adhesion is enhanced if painting is done after a period of exposing to atmospheric influence. In previous long lasting and wide experience in areas of Alaska, under intensive sunshine of Arabic desert, in chemically aggressive environment of Mexican golf, there was no evidence of a structure influence on ultraviolet radiation on long operating life of POLIESTER fibreglass pipes.
Laying of pipes
12.
Pipe installation Installation of POLIESTER pipes can be done in two ways: In trenches – by burring. In underground installation, outside load of material above the buried fibreglass pipe , along with all movable loads, like traffic f. ex. , will induce deflection on circumference of the pipe, which must not be higher than projected. Pipe and material around (soil) accomplish a certain structural system, where both are important for system functioning. As a result, deformation and tension in buried fibreglass pipes strongly depend on, on pipe properties as well as on soil properties. Above ground installation: a) - installation (laying) of fibreglass pipeline directly on field surface b) - fixing (laying) of fibreglass pipeline above the field surface. Requirements for installation of pipeline are basically the same, f. ex. deflection, thermal expansion. Designing a pipeline according to latest technical standards represent a half way to long-lasting and functional pipe system. In order to attain the best result, it is necessary to approach installation very carefully taking care of all details. Final choice of installation type depends on different parameters. For underground installation, It is obligatorily recommended to perform geological -technical soil research , and for slopes steeper than 150 verification based on founded geological-technical research is needed, taking in consideration that stability of supports is directly connected with ground properties.
Above ground pipe installation on steep slopes has many advantages: Easy control of installation quality Changes on the ground (settlement, sliding) are easy to detect, and a problem can be solved fast. Calculation of support type is easier than assessment of soil structure. The load on pipe system is lower, and this is important for pipe anchoring. Any problem on pipe system can be easily solved.
Joint systems for fibreglass pipes There are many systems and variations in those, which satisfy requirements of national standards, and are available for fibreglass pipe products. Many systems comply with requirements of specific projects. Main categories in jointing polyester pipes: Polyester coupling Metal coupling Butt and strap (frontal) connecting joint Flange
13.
POLIESTER coupling Polyester coupling is symmetrical bilateral sliding joint of polyester reinforced with glass fibre. It is delivered with rubber sealing rings and rubber profile - stopper in the middle of coupling. Sealing rings (provide tightness) and stopper (ensures correct position of pipe and sleeve) are placed in chamfers of a coupling, which are precisely mechanically treated. Three parameters contribute efficient sealing with polyester coupling: • Sealing with flippers • Gasket compression • Wedge shaped chamfers Polyester pipe couplings non restrained, guard inner pressure, but not an axial force which can be guarded by restrained pipe couplings. Couplings can be delivered installed on one end of the pipe, or separately if requested.
stopper coupling body
gasket
Graphic outline of joint with polyester coupling
POLIESTER coupling elements pipe beginning pipe end
gasket stopper coupling body
Polyester coupling
Metal coupling Metal coupling - Straub, Teekay and other, are used for pipe joining, as well as for repair operations on pipeline. It may be with opening possibility or fixed. It consists of still mantle with inside rubber sliding gasket. The mantle can be made of stainless steel or coated with special paint.
Metal coupling fixed
Metal coupling with hinge
14.
Butt and strap joint Butt and strap joint is used for joints which need to withhold axial tensions of closure (for pipelines laid under water surface). Joint is made of glass fibre and polyester resin. Joint length and thickness depend on pipe diameter and working pressure. It is mainly used directly in site. This type of joint also guarantees safe and long-lasting type of connection which takes axial loads.
Butt and strap joint
Flanged joint Flanged joint - offers as well reliable jointing and possibility of disassembling in some further phase if necessary. This joining is suitable also for connecting with pipes of other material, as well as valves and various other accessories. Two types of junction with flanges are delivered: • Previously moulded stable flanges on parts of polyester pipe. • Previously moulded movable polyester flanges and muff on polyester pipe.
Joint with stable flanges
15.
Joint with movable flanges
Consulting assistance Our technical support is at your disposal in all areas regarding POLIESTER pipe system: •Assistance in design and selection of most suitable materials considering pressure, stiffness, temperature and corrosion. •Assistance in selecting configuration of pipe installation with all elements. •Assistance with hydraulic pressure calculations. •Assistance with stress calculations for pipeline. •Assistance in form of supervising of construction works.
Reference list Of many projects of small hydro-power plants (SHP), abstracted are some with base characteristics indicated in table below.
Ref. nr.
Buyer - Country
Name
DN (mm)
Stiffness (Pa)
Pressure (bar)
Length (m)
1.
MHE „ERS“ Laktaši, BH
Sućeska I
DN 800 -900
SN 5000
PN 6 -25
4100
2.
MHE „Gorno Belički izvori“ Skopje, Macedonia
Belica I Belica II
DN 600-700
SN 1250 -2500
PN 1 -25
10000
3.
„Eling Inženjering“ d.o.o. Banja Luka, BH
2 power plants
DN 1500 1800
SN 1250 -2500
PN 1 -6
2400
4.
MHE „Ezero“ Skopje, Macedonia
Ohrid I Ohrid II Ohrid III
DN 300-600
SN 1250 -2500
PN 1 -32
3400
5.
„ Rose Wood“ Gornji Vakuf, BiH
3 power plants
DN 4001000
SN 5000
PN 6 -32
6000
6.
„ Paloč“ d.o.o. Gornji Vakuf, BiH
3 power plants
DN 600-800
SN 5000 - 10000
PN 6 -32
7100
7.
MHE „Zagradačka“d.o.o. Prozor, BiH
Zagradačka
DN 500-600
SN 5000
PN 10 -25
1400
8.
Elektro grupa „Jajce” Jajce, BiH
Voljevac
DN 1500 1700
SN 5000
PN 6
1400
9.
„ Vesna S“ d.o.o. Bugojno, BiH
1 power plant
DN 500-700
SN 5000
PN 6 -16
1100
10.
„ Tehel“ d.o.o. Sarajevo, BiH
1 power plant
DN 700
SN 5000
PN 20
500
11.
Vlašić“„ d.o.o. Travnik, BiH
1 power plant
DN 500
SN 5000
PN 10 - 20
1600
12.
„ ECO ENERGY“ d.o.o.Tuzla, BiH
Osanica 4
DN 700
SN 5000
PN 6 - 16
300
13
ADRIJA PRODUKT d.o.o. ZENICA - BiH
Bistričak
DN900-1000
SN 5000
PN6 -10
2100
14
ELKATA - Romania
Elkata
DN350 -1100
SN5000
PN6 -16
5800
15
HIDRO KOP BANJA LUKA- BiH
Paklenica
DN400-500
SN10000
PN10 -16
4000
16
ING EKO PROZOR RAMA -BIH
Duščica
DN1200
N5000
PN6
920
17
MHE „ERS“ Laktaši, BiH
Sućeska II
DN 600-500
SN 5000
PN 6 -30
4100
18
MPP Jedinstvo Sevojno - Serbia
Džep
DN 7001000
SN 5000
PN 10
2700
Note
16.
17.
2400
2300
2200
2100
2000
1900
1800
1700
1600
1500
1400
1300
1200
1100
1000
900
800
700
600
500
450
400
350
300
DN (mm) PN (bar)
SN (Pa) 1
2,5
6 10 16 20 25 32
2500 1
2,5
6 10 16 20 25 32
5000 1
2,5
6 10 16 20 25 32
10 000
Following table shows production programme of GRP POLIESTER pipes
Poliester Grupa d.o.o. Priboj ul. Pribojske čete br. 44 31330 Priboj Srbija
All data and recommendations found in this brochure are given with great care and accuracy. However manufacturer does not accept responsibility for any kind of problems, which may arise as a result of possible errors in this brochure, and in particular with no previous mutual consultations.
18.