Solvent welding is the easiest and most reliable way for joining pipe and fittings for ABS and uPVC pipe systems.
But some knowledge / training is necessary to ensure the perfect joint.
If you require a step-by-step guide on how to solvent weld pipe and fittings along with images, please read the article below.
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Why uPVC?:
- Lightweight - uPVC is much lighter than metal pipework.
- Smooth Bore - prevents lime scale build up inside the pipe.
- Corrosion Resistant.
- Excellent Chemical Resistance - Ideal for the transportation of many acids, alkalis, and chemical concentrates.
- No requirement for specialist insurance cover - i.e., Hot work permits.
- Quick and easy to install - Highly Skilled installers not required, no specialist equipment Reduced installation costs as a result.
- Temperature range - +5°C to +60°C
- Non-toxic - Pipes and fittings are WRAS approved for conveyance of potable water.
Solvent Welding Process
- MEK Cleaner helps to soften / clean / prepare the surfaces to be jointed.
- The solvent cement will soften the surfaces and penetrate into the material.
- The joint must be pushed together quickly and while the surfaces are wet.
- The cement flows between the two surfaces, the chamfer on the pipe helps achieve this.
- As the solvents evaporate, the surfaces of pipe and fitting weld/bond together.
- As the solvents evaporate, the bonds strength increases forming the permanent “homogenous” joint.
Before Starting
- Prevent pipes from breaking or turning oval
- Transport pipes correctly
- Store pipes correctly
In essence try wherever possible to ensure pipe is stored on a flat level surface and that the overall length is supported at both ends at 1 metre intervals.
Peparation for joining
Ensure the conditions are correct:
- Consider the weather... do not work in wind, rain, damp conditions, or direct sunlight.
- Work only in temperatures between +5°C and +25°c if possible.
- Remember that joints performed at low temperatures will take longer to set, in hot temperatures they will set too quick.
- Ensure the workplace is clean, free from dust and is well ventilated.
Make sure you have everything you need:
- Pipes, fittings etc.
- Solvent Cement & Cleaner.
- Brushes.
- Lint free Cloth.
- Tools.
- A vice or similar tool to hold the pipe firm during the jointing process.
Check the equipment before starting:
- Are the pipes and fittings in good condition i.e., pipe is not oval?
- Is your Solvent Cement & Cleaner sufficient in quantity and within date?
- Are your brushes good quality and the correct size?
General Guidelines
- Work only at temperatures between +5°C and +25°C if possible.
- Make sure you work in a clean and dry workplace.
- Work only in a well-ventilated area.
- Prevent risk of condensation.
- Make sure you wear appropriate personal protective equipment (PPE).
Tools Required
Rotary Pipe Cutter
Vice
Chamfering Tool
De-burring Tool
Permanent marker
Brush(es)
Lint free cloth
Solvent resistant gloves
Preparation for joining
For a full step-by-step guide on how to solvent weld pipe and fittings along with images please read the article here.
- Cut pipe to length using an appropriate cutting tool.
- Remove burrs.
- Chamfer edges of pipe.
- Ensure that pipe can be introduced into the mouth of the fitting i.e., the sizes are correct.
- UNI-100* PVC solvent cement is thixotropic so is a gap filling cement (ideal for joints with a looser fit).
*Various other formulations of PVC Solvent Cement available depending on application, details below.
Available Formulations of uPVC solvent cement
UNI-100 - Traditional Thixotropic / gap filling solvent cement for PVC pressure pipework systems.
UNI-100XT - New formulation Thixotropic / gap filling solvent cement which is THF free resulting in a lower odour and reducing the carcinogenic effect.
UNI-100GT - Specially formulated slower setting PVC solvent cement particularly suitable for larger diameter pipework and / or installations carried out in warmer climates, particularly those >35°C.
WDF-05 - Particularly quick setting PVC solvent cement, ideal for use in damp (not wet) conditions for example swimming pool applications and for rigid and flexible PVC tubes and hoses, and/or where a “quick” fix is required.
Chamfering of Pipe
Why Chamfer the Pipe
- Facilitates easier entry of the pipe into the fitting.
- Provides better distribution of the solvent cement inside the joint when the pipe and fitting are pushed together, ultimately resulting in better joints.
- Prevents the solvent cement being pushed out of the joint during assembly.
- Helps to prevent an excess of solvent cement inside the pipe system, which can cause failure.
"Dry" fitting of uPVC Pipes and Fittings
- PVC solvent cements possess excellent gap filling properties.
- For this reason, pipes and fittings with tolerances as opposing ends of the allowable tolerance bands can still be successfully jointed together.
- Some engineers prefer to “dry” fit product prior to permanent installations to calculate system layout and/or mark the insertion depth of the fitting on the pipe. This is more likely in smaller diameter PVC systems but, depending on the brand of product, cannot be guaranteed.
- Pipe and fittings are rarely produced by the same manufacturer but are produced to the compatible standards EN1452-2/3. If the pipe and fittings are produced within the tolerances stated in the relevant standard, the product conforms, whether the joint be tight or a little looser. In joints that cannot be “dry” fitted, the solvent cement, once applied, also acts as a lubricant aiding the insertion of the pipe into the fitting.
Is it necessary to Abrade?
The combination of Griffon solvent cements and Cleaner are more than strong enough to give high strength joints. Abrading is no longer necessary to increase the strength of the joints.
Only when pipes are discoloured because of storage in direct sunlight for instance, does abrading aid in the preparation of the joint, as it helps to remove the oxidised layer on the outside of the pipe.
Is it necessary to use MEK Cleaner
Use Griffon Cleaner to soften and clean the surfaces to be joined. Always use clean absorbent lint free paper. Softening the PVC material optimises the cold welding process to give better bonding. Griffon solvent cement and Griffon Cleaner work together like a team. All testing / approvals are based on combination of Griffon solvent cement and Cleaner. So do not use other brands of cleaners or solvents in conjunction with Griffon product.
- Dirty, greasy Pipes and Fittings
- Diameters ≥ 3”
- For pipe systems conveying chemicals
Precautions - Environmental Stress Cracking (ESC)
This is unexpected failure of thermoplastics polymers such as ABS and uPVC.
The action of either a tensile stress or a corrosive chemical alone is not always enough to cause failure in the plastic, but in ESC the initiation and growth of a crack is caused by the combined action of the stress and a corrosive chemical.
The solvents used for solvent cements are aggressive chemicals for ABS and uPVC. That is a positive because the solvents are essential for good jointing / cold welding between the pipe and fitting. But it is not good when we have an of excess of the solvent cement inside of the pipe system on places where tensile stress is. This is typical where solvent cement has been allowed to “pool” inside the joint.
Steps to avoid Environmental Stress
- Avoid an excess of solvent cement / “pooling” inside the pipe systems
- Always chamfer the pipe.
- Do not apply too much solvent cement in the fitting (thin coat).
- Do not use large brushes for small fittings.
- Avoid tensile stress in the pipe system. Elbows and T-Junctions can be sensitive if not free of stress when installed. Be aware of stress because of temperature differences in pipe system. Be aware that heat formed fittings already have stress in the material.
- Remember that uPVC is more sensitive/brittle at lower temperatures (< 5°C) for and more prone to environmental stress cracking.
- Prior to the pipe system being operational do not close off or fill it with water but allow to it ventilate for as long as possible.
- Risk decreases with increasing pipe diameter due to the thicker wall of the fitting.
Avoid stress in the pipe system
Avoid an excess of solvent cement inside the pipe systems
Avoid low temperatures during installing
Extreme Conditions
High temperatures / tropical conditions (>+25°C)
- Actions have to be executed much faster
- Work with more personnel at the same time on the same joint
Low temperatures (<+5°C)
- Allow extended drying times (solvent evaporates slower)
- Avoid moisture (cools down surfaces being bonded slowing down evaporation of solvents and causing moisture)
- Warm up parts to be bonded (temperature preferably around +20°C)
Condensation
- Consequence - Adhesive failure
- Note there is an even higher risk at high relative humidity
Precautions
Avoid plastic to metal threaded connections at all costs
- Plastics expand/contract at different rates, particularly where temperatures vary by +/-5ºc or more, which can cause plastic threads to fracture.
- Use Composite Unions or Flanges to connect the two different materials together.
Use only approved thread sealing tapes on plastic joints
- Most paste type jointing compounds contain ingredients that can chemically attack ABS ultimately causing product failure.
- We recommend the use of PTFE Tape or Kolmat Fibre Seal. Kolmat Fibre Seal offers the following advantages over traditional PTFE tape - universal, fibre-reinforced, adjustable > 180°, removable.
Ensure that pipes are always bracketed in accordance with manufacturers guidelines
- Use approved pipe clips / brackets only such as the industrial pipe clips.
- The use of rubber lined pipe clips should be exercised with caution as their linings can contain substances known as `phthalates` which can be harmful to uPVC.
Ensure pipe contents are prevented from freezing
- This can result in system failure.
- Take precautions when using pipe insulation or trace heating tape as certain types can cause chemical attack to the PVC pipework. The following list, whilst not exhaustive, is a list of common types of insulation that are known to be suitable for use with PVC pipe -Recommended insulation -Fibre wool, such as `Rockwool`, Armaflex Class 1 HT, Phenolic foam, Polystyrene.
Ensure allowances are made for system expansion & contraction
- Plastic pipework systems installed above ground should have adequate provision for expansion and contraction, which can be achieved by sufficient changes in direction, expansion loops or expansion bellows.
Pressure Testing
Ensure heavy pieces of equipment are adequately supported
- Un-supported, heavy pieces of equipment can cause undue stress to PVC pipe systems, ultimately causing system failure. This can be achieved by utilising valve support plates or pipe clips with spacing blocks for instance. Spacing blocks can also be used in instances where the pipe needs to be spaced “away” from the wall, for instance where socket unions or ball valves are installed.
Pressure testing of pipes
- Should always be carried out with water, NOT air.
- Always ensure joints are thoroughly cured before pressure testing.
- Fill the system with cold water from the lowest point, leaving the system open at the highest to allow air to escape. Do not introduce pressure at this stage. Ensure no air pockets remain and close the system.
- Inspect for and rectify any leaks.
- Slowly fill the system to 3 bar pressure and leave for 10 minutes. If pressure drops, identify, and rectify leaks.
- Slowly increase pressure to 1½ times the maximum working pressure of the system and leave for one hour. Pressure should not change during this time.
Precautions
Solvent cements and cleaners contain solvents/chemicals hazardous to health, however this is necessary for the desired result
- Read the safety instructions on the label of the product and consult the safety data sheet (MSDS).
- Respect the safety instructions.
Minimize the risk of exposure to solvents
- Ventilate well, at the lowest place possible (solvents are heavier than air).
- Immediately close packaging after use and deposit cleaning-rags etc. in a closed container.
Use appropriate personal protection equipment
- Prevent skin contact: use a barrier cream, wear safety gloves.
Prevent respiration
- In closed areas use appropriate respiratory equipment.
Work under normal hygienic conditions
- Do not smoke, eat, or drink during work.
- Before breaks (eat, drink) take off work clothes and wash hands with water and soap.
When not being used, store closed containers of solvent correctly.
- In closed, lockable, metal containers or cabinets.
UNI-100 PVC Cement
