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Hdpe Pipes & Fittings

HDPE PRESSURE PIPIE SYSTEMS

High density polyethylene pipe has been used extensively around the world since the 1950’s.The unique properties of High density polyethylene pipe have offered an alternative to traditional material like steel and copper and also in non pressure applications where clay and fibre cement pipes were used . The material has been developed internationally from PE 80 to today’s PE 100 material which has shown a saving of approximately 30% on the wall thickness from the early days of Polyethylene. This mass saving relates back to a cost saving and a better performance as the internal diameter of the pipe is bigger. In many cases, because of the excellent flow characteristics of Polyethylene, pipes could be down sized while still performing within the expected parameters. The pipes’ properties such as impact resistance and resistance to abrasion have made HDPE pipe the obvious choice in the Infrastructure, Civil Engineering, Mining and Industrial markets.
Piping made from polyethylene is a cost effective solution for a broad range of piping applications in the municipal,water networks, industrial, marine, mining, landfill, duct and agricultural industries. It has been tested and proven effective for above ground, surface, buried, slip-lined, floating and sub-surface marine applications.
High-density polyethylene pipe (HDPE) can carry clean water, potable water, wastewater, slurries, chemicals, hazardous wastes, and compressed gases. In fact, polyethylene pipe has a long and distinguished history of service in the gas, oil, mining and other industries. It has the lowest repair frequency per kilometer of pipe per year compared with all other pressure pipe materials used for urban gas distribution.
Polyethylene is a strong, extremely tough, very durable product which offers long service and trouble-free installation.

Applications

MHigh Density Polyethylene pressure pipes are specified with confidence in the following applications:

Civil engineering. Water mains and reticulation systems

Building. House connections and water reticulation systems

Agriculture. Irrigation and water supply schemes

Industrial.Conveyance of chemicals and water in most industrial plants

Mining. Conveyance of water and air in underground operations. Used extensively in treatment and recovery plants.

HDPE is generally used for high pressure applications ranging from 3.2 to 25 Bar, in conjunction with compression, buttweld or electrofusion fittings. MEGA-THERM HDPE piping conforms to the TSE ISO 4427-1:2007 specification

HDPE Material

Polyethylene pressure pipe systems offer many advantages when compared to traditional products, namely: 

* Weather resistance in above ground applications 

* Highly corrosion resistant 

* Ease of handling and installation, exceptional toughness 

* Excellent abrasion resistance 

* Manufactured in long lengths and coils 

* Manufactured to internationally accepted standards 

* Service performance in excess of 50 years

Resistance to weather degradation 

Carbon black in the formulation of the pipe raw material enables HDPE pipe to resist degradation by ultraviolet rays. The pipe is impervious to rain and wind conditions.

Chemical resistance

HDPE pipes are chemically inert but there are some chemicals which could affect the pipe. As the product is also not electrically conductive, reactions cannot take place within the pipe and affect its performance.

HDPE has excellent corrosion resistance and is virtually inert so it does not need expensive cathodic protection. It offers better resistance to corrosive acids, bases and salts than most piping materials and also has good resistance to many organic substances such as solvents and fuels.

Natural soil chemicals cannot degrade the pipe in any way.

Ease of handling 

Conventional materials are much heavier than HDPE and will require cranes and lifting gear. Handling of the product can often be done by hand allowing ease of installation in confined spaces and difficult terrain.

High strength and flexibility 

HDPE material has a high degree of impact resistance and is robust and ductile. Pipes can bend quite easily allowing for savings in design as less critical angle changes can be made without bends. HDPE pipe can be laid across uneven surfaces and in narrow trenches. Pipe can be joined outside of the trench before installation into the trench. The ability to absorb pressure surges makes the product superior to other plastic pipe materials.
Even in sub zero temperatures HDPE can still perform to expectation.

Resistance to abrasion 

Where very abrasive mediums have to be transported HDPE has proved itself to be the pipe product of choice. HDPE outperforms traditional pipe materials such as steel and steel with sacrificial layers (rubber lined steel).
The product is used extensively in mine tailings and washing plants.

Co-efficient of friction 

The smooth internal surface of the pipe and the impermeability of HDPE allows a greater flow capacity and minimal friction loss. It has less drag and a lower tendency for turbulance at high velocity. Its superior chemical resistance and non-stick surface combines to eliminate scaling and pitting. This preserves the excellent hydraulic characteristics throughout the pipe’s service life.
When designing pipelines, use the Hazen-Williams C factor of 150 and an n factor of 0.009, when using the Manning formula.

Specifications

The TS 418 / EN 12201 1-2, ISO 4427, DIN8074-D1N 8075 specification has been superceded in part by the adoption of the  TS 418 / EN 12201 1-2, ISO 4427, DIN8074-D1N 8075 for HDPE pipe systems.

The following table shows which specifications are currently applicable for LDPE and HDPE pipe systems:  

TSE 418 / EN 12201 1-2 ISO 4427 – 1 / 2007
Part 1: LDPE Tip I
Part 2: HDPE Tip IV PE 63 HDPE
Part 3: HDPE Tip V PE 80 HDPE
PE 100 HDPE

Product range
HDPE PE 80 (Type V) is based on a design stress value of 6.3MPa, which results in the manufacturing of pipe with a thinner wall, and consequently greater ID than the PE 63 (Type IV) specification. This results in material savings and improved flow characteristics.

Notes: 

* The HDPE pipe dimensions and pressure classes in the TSE ISO 4427-1/2007 specification remain unchanged when compared to the  533: Parts 2 and 3 specification, except where calculated in terms of   ISO 4065.

* The adoption of the ISO 4427-1/2007 specification has resulted in the change of notation for HDPE piping from Types IV and V to PE 63 and 80. The 63, 80 and 100 refer to various grades of HDPE polymer and their design stresses. 

* The TSE 418/EN 12201 1-2 Part 1 specification remains in force and is applicable to LDPE systems only.

HDPE PE 100 pipe is based on a design stress value of 8.0MPa, which results in an even thinner pipe wall thickness than PE 80 pipe due to the higher grade of material.
.

PE 100 PE 80 (T ype V) PE 63 (Type IV)
Pressure classes  PN 4, 6.3, 8, 10, 12.5, 16, 20 and 25 PN 3.2, 4, 6.3, 8, 10, 12.5, 16 and 20 PN 3.2, 4, 6.3, 8, 10, 12.5 and 16
Working pressures 400, 630, 800, 1000, 1250, 1600, 2000 & 2500 kPa 320, 400, 630, 800, 1000, 1250, 1600 & 2000 kPa 320, 400, 630, 800, 1000, 1250 & 1600 kPa
Design stress 8.0 MPa 6.3 MPa 5.0 MPa
Pipe size Pipe lengths
16mm 63mm  6m 9m 12m 30m 50m 100m 400m
16mm 63mm  6m 9m 12m 30m 50m 100m on request. Not standard
16mm 63mm  6m 9m 12m 13,5m 24m on request only. Transport dependant 

Jointing systems

HDPE pipes can be joined using the following methods:

Compression fitting
Size 16 to 160mm
Pressure PN 16 (16 to 110mm) PN 10 (160mm)
Range Complete range of elbows, couplings and flange adaptors
Stub flange and backing ring
Size 50 to 630mm
Drilling TD T10 to 16 and ASA 150
Electrofusion and buttweld fittings
Size 20 to 630mm
Pressure PN 4 – PN 25
Range Complete range of elbows, couplings and adaptors
Takstubs and victaulic stubsr
Size 63 to 315mm
Pressure PN 16 (Takstubs) – PN 10 (Victaulic) 
Range Fitted to either coils or straight lengths

HDPE pipe dimensions

 

 

Temperature / Pressure derating

The rated working pressure of an HDPE pipe is determined oat 20°C. Where the operating temperature of the fluid in t he pipe exceeds 20°C,  the pressure rating of the pipe  has to be de-rated in order to maintain the designed safety factors of the pipe.

HDPE pipe is not recommended in applications where the fluid temperature exceeds 50°C.

Temperature of fluid in the pipe
Derating factor apply to maximum working pressure
0 – 20 1,0
20 – 25 0,9
25 – 30 0,8
30 – 35 0,7
35 – 40 0,6
40 – 45 0,5
45 – 50 0,4

Design guidelines

Physical properties Units HDPE
Density Kg/m³ 0,958 x 10³
Co-efficient of linear expansion K‾¹ 16 x 10‾³
Thermal conductivity at 20⁰ C W/m/K 0,50
Specific heat J/kg/K 2,3 x 10‾³
Softening point (Vicat) ⁰C 67
Flammability Flammable
Mechanical properties Units HDPE
Tensile strength at yield MPa³ 26³
Elongation at yield % 10
Modulus of elasticity MPa 900
Rockwell hardness (Shore) 61
Dielectric strength kV/mm 70

Codes of Practice

Handling

Pipes manufactured in HDPE are strong, durable and easy-to-handle. In common with most construction materials, they should nevertheless be handled with care to avoid damage being caused to the pipes. 

Storage

Pipes should be stored on level, flat ground, free of stones or sharp protrusions. The height of the stacked pipe should not exceed 5 coils. Normal exposure to direct sunlight during the contract will not damage the pipe. 

Cutting

Carefully cut the pipe ends square using a fine-toothed hand saw. Remove burrs and cutting debris. 

Fusion & Jointing

The principle behind heat fusion is to heat two surfaces to a designated temperature, and then fuse them together by application of a sufficient force. This applied force causes the melted materials to flow and mix, resulting in a permanent, monolithic fusion joint. When fused according to the recommended procedures, the fusion or joint becomes as strong as or stronger than the pipe itself in both tensile and pressure properties. MEGA-THERM fusion procedures require specific tools and equipment for the fusion type and for the sizes of pipe and fittings to be joined.

* Butt Fusion   – This technique consists of heating the squared ends of two pipes, a pipe and fitting, or two fittings by holding them against a heated plate, removing the plate when the proper melt is obtained, promptly bringing the ends together and allowing the joint to cool while maintaining the appropriate applied force.

* Saddle Fusion  – This technique involves melting the concave surface of the base of a saddle fitting, while simultaneously melting a matching pattern on the surface of the pipe, bringing the two melted surfaces together and allowing the joint to cool while maintaining the appropriate applied force. 

* Socket Fusion  – This technique involves simultaneously heating the outside surface of a pipe end and the inside of a fitting socket, which is sized to be smaller than the smallest outside diameter of the pipe. After the proper melt has been generated at each face to be mated, the two components are joined by inserting one component into the other. The fusion is formed at the interface resulting from the interference fit. The melts from the two components flow together and fuse as the joint cools. 

* Electrofusion Fittings  – Electrofusion fittings have a separate set of jointing instructions. Ensure that you obtain and follow the specific information when you purchase them.

* Compression Fittings  – Clean the pipe end, lightly lubricate both the interior of the fittings and the pipe end. Slacken the nut and insert the pipe fully into the fitting. Tighten the nut – hand tight and a quarter turn with a strap wrench or nut spanner. NOTE: Do not overtighten. Overtightening may cause the assembly to leak.

Properly fused polyethylene joints do not leak. If a leak is detected during hydrostatic testing, it is possible for a system failure to occur. Caution should be exercised in approaching a pressurized pipeline and any attempts to correct the leak should not be made until the system has been depressurized. 

Note: Polyethylene cannot be joined by solvent bonding or threading. Extrusion welding or hot air welding is not recommended for pressure applications.

Inclement Weather

Polyethylene has reduced impact resistance in sub-freezing conditions. Additional care should be exercised while handling in subfreezing conditions. In addition, polyethylene pipe will be harder to bend or uncoil.

In inclement weather and especially in windy conditions, the fusion operation should be shielded to avoid precipitation or blowing snow and excessive heat loss from wind chill. The heating tool should also be stored in an insulated container to prevent excessive heat loss. Remove all frost, snow or ice from the OD and ID of the pipe; all surfaces must be clean and dry prior to fusing. The time required to obtain the proper melt may increase when fusing in cold weather. The following recommendations should be followed:

1. Maintain the specified heating tool surface temperature. Do not increase the tool surface temperature. 

2. Do not apply pressure during zero pressure butt fusion heating steps. 

3. Do not increase the butt fusion joining pressure.

In butt fusion, melt bead size determines heating time; therefore, the procedure automatically compensates when cold pipe requires longer time to form the proper melt size. The outside diameter of polyethylene pipe and fittings will contract in cold weather conditions. This can result in loose or slipping cold rings. For best results, clamp one cold ring in its normal position adjacent to the depth gage. Shim around the pipe behind the clamp with paper, tape, etc., and place a second cold ring over this area. This cold ring will prevent slippage while the inner cold ring will allow for the pipe to expand during the heating cycle of the fusion process. 

The proper cycle time for any particular condition can be determined by making a melt pattern on a piece of scrap pipe using the recommended standard heating time. If the melt pattern is incomplete, increase the heating time by three (3) second intervals until a complete melt pattern is established. Each time the procedure is repeated, a new piece of scrap pipe should be used. For additional information concerning cold weather procedures, refer to ASTM D2657-07, Standard Practice for Heat Fusion Joining of Polyolefin Pipe and Fittings Plastic Pipe Institute PPI TN-42: Recommended Minimum Training Guidelines for PE Pipe Butt Fusion Joining Operators for Municipal & Industrial Projects.

Notes On Fusion Confidence

Reliable fusion joints of polyethylene piping systems can be accomplished under reasonable latitude of conditions. The following is a listing of general notes to help ensure proper equipment and techniques are utilized:

1. The fusion operator must have adequate training and understanding of the equipment and tools and the fusion procedure

Improper understanding of the operation of the equipment and tools can produce a fusion of poor quality. The operator must understand thoroughly how to use the equipment and tools, their function and operation. The operator should adhere to the equipment manufacturer’s instructions.

Contact pressures and heating/cooling cycles may vary dramatically according to pipe size and wall thickness. Operators should not rely exclusively on automated fusion equipment for joint qualification. In addition, visual inspection and qualification should always be made. If necessary, test fusions should be made to determine correct pressures and heat/cool cycle times. Destructive test methods, such as bend back tests, may be necessary to formulate correct pressures and heat/cool cycle times (refer to Qualification Procedures).  

2. Pipe and fitting surfaces must be clean and properly prepared .

Any contaminants present on the surfaces or poor preparation of the surfaces cannot produce a quality fusion joint. Ensure that all pipe and fitting surfaces are clean. If surfaces are reintroduced to contaminants, they should be cleaned again. 

3. Heater plates must be clean, undamaged and the correct surface temperature. 

Heater surfaces are usually coated with a non-stick material. Cleaning techniques should be used accordingly. If a solvent is deemed necessary, do not use gasoline or other petroleum products. Refer to the equipment manufacturer’s instructions for proper cleaning products. 

Recommended heating tool temperatures are specified for each procedure. This temperature is indicative of the surface temperature, not the heating tool thermometer. The surface temperature should be verified daily by using a surface pyrometer. If a crayon indicator (melt stick) is used, it should not be used in an area that will be in contact with the pipe or fitting. If the heater plate is not in use, it is recommended that it be stored in an insulated holder. This not only protects the heater surfaces from contaminants, but it can also prevent inadvertent contact, which can result in serious injuries.

4. Proper equipment and condition of tools and equipment for the job

Each type of fusion requires special tools and equipment. Fusions performed with the incorrect fusion equipment, materials or tools can result in a poor fusion.

Fusion Checklist

Inspect pipe lengths and fittings for unacceptable cuts, gouges, deep scratches or other defects. Damaged products should not be used. Refer to InfoBrief No. 4 for allowable surface damage according to the Plastics Pipe Institute (PPI) and the American Gas Association (AGA). Any surface damage at pipe ends that could compromise the joining surfaces or interfere with fusion tools and equipment should be removed. Be sure all required tools and equipment are on site and in proper working order. Pipe and fitting surfaces where tools and equipment are fitted must be clean and dry. Use clean, dry, non-synthetic (cotton) cloths or paper towels to remove dirt, snow, water and other contaminants. Shield heated fusion equipment and surfaces from inclement weather and winds. A temporary shelter over fusion equipment and the operation may be required. Relieve tension in the line before making connections. When joining coiled pipe, making an S-curve between pipe coils can relieve tension. In some cases, it may be necessary to allow pipe to equalize to the temperature of its surroundings. Allow pulled-in pipes to relax for several hours to recover from tensile stresses. Pipes must be correctly aligned before making connections. Trial fusions. A trial fusion, preferably at the beginning of the day, can verify the fusion procedure and equipment settings for the actual jobsite conditions. Refer to Qualification Procedures for detailed information on the bend back test procedure. 

Butt Fusion

Heater Surface Temperature;

Minimum 400 F – Maximum 450 F (204 – 232  C) Heating tool surfaces must be to temperature before you begin. All points on both heating tool surfaces where the heating tool surfaces will contact the pipe or fitting ends must be within the prescribed minimum and maximum temperatures and the maximum temperature difference between any two points on the heating tool fusion surfaces must not exceed 20 F (11 C) for equipment for pipe smaller than 18” diameter, or 35 F (19  C) for larger equipment. Heating tool surfaces must be clean. 

Interface pressure ; Minimum 60 psi – Maximum 90 psi (414 – 621 kPa; 4.16 – 6.21 bar) Interface pressure is used to calculate a fusion joining pressure value for hydraulic butt fusion machines or manual machines equipped with force reading capability. The interface pressure is constant for all pipe sizes and all butt fusion machines. However, fusion joining pressure settings are calculated for each butt fusion machine, which are dependent upon the OD and DR (Dimension Ratio). For hydraulic machines, the interface pressure, the fusion surface area, the machine’s effective piston area and frictional resistance, and if necessary, the pressure needed to overcome external drag resistance, are used to calculate hydraulic fusion joining pressure gauge settings (refer to Appendix A). The equipment manufacturer’s instructions are used to calculate this value. The proper amount of force should be verified by visual inspection of the joint. 

NOT: The interface pressure and the hydraulic gauge pressure are not the same. 

For manual machines without force reading capability, the correct fusion joining force is the force required to roll the melt beads over to the pipe surface during joining.

Procedure

1. Secure

Clean the inside and outside of the component, pipe or fitting ends by wiping with a clean, dry, lint-free cloth or paper towel. Remove all foreign matter. Align the components of the machine, place them in the clamps, and then close the clamps. Do not force pipes into alignment against open fusion clamps. Component ends should protrude past the clamps enough so that facing will be complete. Bring the ends together and check high-low alignment. Adjust alignment as necessary by tightening the high side down.

2. Face

Place the facing tool between the component ends, and face them to establish smooth, clean, parallel mating surfaces. Complete facing produces continuous circumferential shavings from both ends. Face until there is minimal distance between the fixed and moveable clamps. If the machine is equipped with facing stops, face down to the stops. Stop the facer before moving the pipe ends away from the facer. Remove the facing tool, and clear all shavings and pipe chips from the component ends. Do not touch the component ends with your hands after facing. 

3. Align

Bring the component ends together, check alignment and check for slippage against fusion pressure. Look for complete contact all around both ends with no detectable gaps, and outside diameters in high-low alignment. If necessary, adjust the high side by tightening the high side clamp. Do not loosen the low side clamp because components may slip during fusion. Re-face if high-low alignment is adjusted. 

4. Melt

Verify that the contact surface of the heating tool is maintaining the correct temperature. Place the heating tool between the component ends, and move the ends against the heating tool. Bring the component ends together under pressure to ensure full contact. The initial contact pressure should be held very briefly and released without breaking contact. Pressure should be reduced when evidence of melt appears on the circumference of the pipe. Hold the ends against the heating tool without force (drag force may be necessary to ensure contact). Beads of melted polyethylene will form against the heating tool at the component ends. When the proper melt bead size is formed, quickly separate the ends, and remove the heating tool. The proper bead size is dependent upon the size of the component. Approximate values are shown in Table I.

Tablo 1 Approximate Melt Bead Size 
Approximate Wall Thickness , inches Melt Bead Size* (Approximate) 
≤ 0,15 3,8 mm and smaller 1/32” – 1/16” 1 – 2 mm
0,15 – 0,30 3,8 mm – 7,6 mm 1/16” 2 mm
0,30 Above – 0,75 7,6 mm.nin Above – 19 mm 1/” – 3/16” 3 – 5 mm
0,75 Above – 1,15 19 mm.nin Above – 29,2 mm 3/16 – ¼” 5 – 6 mm
1,15 Above – 1,60 29,2 mm.nin Above – 40,6 mm ¼” – 5/16” 6 – 8 mm
1,60 Above – 2,20 40,6 mm.nin Above – 55,9 mm 5/16” – 7/16” 8 – 11 mm
2,20 Above – 3,00 55,9 mm.nin Above – 76,2 mm 7/16” – 9/16 11 mm
*The appearance of the melt swell zone may vary depending on the pipe material. The melt bead width is   to be determined by measuring the distance from the heater  plate to the melt swell origin.  

During heating, the melt bead will expand out flush to the heating tool surface, or may curl slightly away from the surface. If the melt bead curls significantly away from the heating tool surface, unacceptable pressure during heating may have occurred.

5. Join

Immediately after the heating tool is removed, quickly inspect the melted ends, which should be flat, smooth and completely melted. If the melt surfaces are acceptable, immediately and in a continuous motion, bring the ends together and apply the correct joining force (or fusion pressure). The correct fusion pressure will form a double bead that is rolled over to the surface on both ends. A concave melt surface is unacceptable; it indicates pressure during heating. Do not continue. Allow the component ends to cool and start over with Step 1.

6. Hold

Hold joining force against the ends until the joint is cool. The joint is cool enough for gentle handling when the double bead is cool to the touch. Cool for about 30 – 90 seconds per inch of pipe diameter. Do not try to decrease the cooling time by applying water, wet cloths or the like. Avoid pulling, installation, pressure testing and rough handling for at least an additional 30 minutes. Heavier wall thickness pipes require longer cooling times.

7. İnspection

On both sides, the double bead should be rolled over to the surface, and be uniformly rounded and consistent in size all around the joint.

1. The gap (A) between the two single beads must not be below the fusion surface throughout the entire circumference of the butt joint.

2. The displacement (V) between the fused ends must not exceed 10% of the pipe/fitting minimum wall thickness.

3. Refer to Table II for general guidelines for bead width, B, for each respective wall thickness. 

Tablo II Bead Widths per Wall Thickness 
Minimum Wall Thickness, in. Approximate Bead Width (B), in. Minimum Wall Thickness, in.  Approximate Bead Width (B), in.
Minimum Maksimum Minimum Maksimum
,0118 5/32 ¼ 1,06 19/32 25/32
,157 5/32 9/32 1,18 5/8 13/16
,197 3/16 5/16 1,34 21/32 7/8
,246 ¼ 11/32 1,57 11/16 29/32
,315 9/32 3/8 1,77 25/32 1
,354 5/16 7/16 1,97 7/8 1-1/16
,433 11/32 ½ 2,16 15/16 1-3/16
,512 3/8 9/16 2,36 1 1-1/4
,630 7/16 19/32 2,56 1-1/8 1-7/16
,710 ½ 5/8 2,76 1-3/16 1-1/2
,750 ½ 11/16 2,95 1-1/4 1-9/16
,870 ½ 11/16 3,15 1-5/16 1-11/16
,940 9/16 ¾ 3,35 1-3/8 1-3/4
  3,54 1-1/2 1-13/16

Instructions:

Determine the wall thickness of the pipe/fitting.  Find the wall thickness above.  If the exact wall thickness is not shown, use the next lowest wall thickness for determination of bead width. 

4 – The size differential (Smax – Smin ) between two single beads shall not exceed X% of the actual bead width (B).   

Where

X = Percent difference of bead width, % 

Pipe to pipe, maximum X = 10% 

Pipe to fitting, maximum X = 20% 

Fitting to fitting, maximum X = 20% 

S = Smax – Smin, inches 

B = Width of bead, inches 

NOTE: When butt fusing to molded fittings, the fitting side bead may have an irregular  appearance.  This is acceptable provided the pipe side bead is correct.

Qualification

1. Prepare a sample joint. Sample lengths should be at least 6” or 15 times the minimum wall thickness (see Figure I). 

2. Observe the fusion process and verify the recommended procedure for butt fusion is being followed. 

3. Visually inspect the sample joint for quality. 

4. Allow the joint to cool completely (minimum of one hour). 

5. Prepare the sample as shown in Figure I. The sample should be cut lengthwise into at least three longitudinal straps with a minimum of 1” or 1.5 times the wall thickness in width.

6. Visually inspect the cut joint for any indications of voids, gaps, misalignment or surfaces that have not been properly bonded.

7. Bend each sample at the weld with the inside of the pipe facing out until the ends touch. The inside bend radius should be less than the minimum wall thickness of the pipe. In order to successfully complete the bend back, a vise may be needed. For thick wall pipe, a hydraulic assist may be required. 

8. The sample must be free of cracks and separations within the weld location. If failure does occur at the weld in any of the samples, then the fusion procedure should be reviewed and corrected. After correction, another sample weld should be made per the new procedure and re-tested.

ACCEPTABLE FUSIONS 

Proper alignment and double roll-back bead.

Unaceptable Fusions

Melt bead too small due to insufficient heat time. 

Melt bead too large due to excessive heating and/or over-pressurizing of joint.

Misalignment.

Incomplete facing.

Butt Fusion Troubleshooting Guide 

Tablo 3 Butt Fusion Troubleshooting Guide 
Observed Condition  Possible Cause
Excessive double bead width

Overheating

Excessive joining force

Double bead v-groove too deep 

Excessive joining force 

Insufficent heating

Pressure during heating

Flat top on bead 

Excessive joining force

Overheating

Non-uniform bead size around pipe 

Misalignment  

Defective heating tool  

Worn equipment  

Incomplete facing 

One bead larger than the other

Misalignment

Component slipped in clamp

Worn equipment

Heating iron does not move freely in the axial direction

Defective heating tool

Incomplete facing

Beads too small

Insufficient heating  

Insufficient joining force 

Bead not rolled over to surface

Shallow v-groove – Insufficient heating & insufficient joining force

Deep v-groove – Insufficient heating & excessive joining force

Beads too large Excessive heating time 
Excessive heating time  Pressure during heating
Rough, sandpaper-like, bubbly, or pockmarked melt bead surface  Hydrocarbon (gasoline vapors, spray paint fumes, etc.) contamination

Flow/friction loss chart

For use with PE 63, 80 and 100

Use of flow chart

Example : HDPE 110 Class 10 pipe, PE63 (Type IV)

1. Determine inside diameter : DIA – (2 x wall thickness) 110 – (2 x 10.0) = 90.0 mm

2. Select the velocity : Say 1.0 metres per second
.

3. Method : Place ruler on 90 in Column A and on 1.0 in column C. The delivery and friction loss are read from Columns B and D.

Chemical resistance table

The following chart rates the resistance of unplasticised polyvinylchloride, polyethylene, polypropylene and two commonly used rubber seal rings to various chemicals at various concentrations and temperatures. The chart is intended as a guide only and should not be regarded as
applicable to all working conditions. Should there be any doubt about the behaviour of the pipe under specific conditions, please contact the Technical Department.
Use the index below as a reference guide to the tables which follow.

 

 

 

Explanation of symbols:

∇ Resistant

Ø Conditionally resistant (more favourable at temperatures lower than those quoted)  

– Not Recommended

MEGA-THERM Injection Fittings

MEGA-THERM Confection Fittings

MEGA-THERM Electrofusion Fittings