To make consistently good joints, the following points should be clearly understood.
- The joining surfaces must be softened and made semi fluid.
- Sufficient cement must be applied to fill gap between pipe and fitting.
- Assembly of pipe and fittings must be made while the surfaces are still wet and cement is still fluid.
- Joint strength develops as the cement dries. In the tight part of the joint the surfaces will tend to fuse together; in the loose part, the cement will
- bond to both surfaces. These areas must be softened and penetrated.
More than sufficient cement to fill the loose part of the joint must be applied. Besides filling the gap, adequate cement layers will penetrate the surfaces and also remain wet until the joint is assembled. Prove this for yourself. Apply on the top surface of a piece of pipe two separate layers of cement. First apply a heavy layer of cement; then along side it, apply a thin brushed out layer. Test the layers every 15 seconds or so by a gentle tap with your finger. You will note that the thin layer becomes tacky and then dries quickly (probably within 15 seconds); the heavy layer will remain wet much longer. A few minutes after applying these layers check for penetration. Scrape the surface of both with a knife. The thin layer will have achieved little or no penetration; the heavy one will have achieved much more penetration. If the cement coatings on the pipe and fittings are wet and fluid when assembly takes place, they will tend to flow together and become one cement layer. Also, if the cement is wet, the surfaces beneath them will still be soft and these softened surfaces in the tight part of the joint will tend to fuse together.
As the solvent dissipates, the cement layer and the softened surfaces will harden with a corresponding increase in joint strength. A good joint will take the required working pressure long before the joint is fully dry and final joint strength is obtained. In the tight (fused) part of the joint, strength will develop more quickly than in the looser (bonded) part of the joint.
BEFORE CEMENTING
Review all directions on the cement container label or the standard practice for making solvent-cemented joints.
Assemble materials needed for the installation (the proper cement and applicator for the size of pipe and fittings to be assembled).
Pipe must be cut as square as possible. A diagonal cut reduces bonding area in the most effective part of the joint.
Remove all burrs from both inside and outside of the pipe with a knife, file or reamer. Burrs can scrape channels into pre-softened surfaces or create hang-ups inside surface walls.
Remove dirt, grease and moisture. A thorough wipe with a clean dry rag is usually sufficient. Moisture will retard cure and dirt or grease can prevent adhesion.
Check pipe and fittings for dry fit – For proper interference fit, fitting should go over end of pipe easily but become tight about 1/3 to 2/3 of the way on. (A good interference fit is desired for a one-step installation).
Check for penetration and softening of the pipe’s surface. Take a scrap piece of the pipe you will be using and make a normal application of the cement. Then immediately, using a knife or other sharp object, try to scratch or scrape a few thousandths of the surface away. If you are able to do so, proceed with installation. If not, try making a more aggressive application of the cement on the scrap piece of pipe and check for penetration as noted above. If you still are unable to achieve penetration or softening of the pipe’s surface, you may want to consider the use of a primer.
Using the correct size applicator (1/2 the pipe diameter), aggressively work solvent cement on the end of the pipe equal to the depth of the fitting socket.
Next, aggressively work cement into fitting socket – being careful not to get cement into waterway.
Then apply a second layer of cement on to the end of the pipe equal to the depth of the fitting socket.
Immediately and while the surfaces are still wet, assemble the pipe and the fitting using sufficient force to ensure that the pipe bottoms into the fitting socket. If possible, twist the pipe a 1/4 turn as you insert it. Stop turning when pipe hits bottom.
Hold the pipe and fitting together for approximately 30 seconds to eliminate push out.
After assembly, the joint should have a ring or bead of cement completely around the juncture of the pipe and fitting. If voids in this ring are present, sufficient cement was not applied and the joint may be defective. Using a rag, remove all the excess cement from the pipe and fitting, including the ring or bead.
JOINING PLASTIC PIPE IN HOT WEATHER
There are many occasions when solvent cementing plastic pipe at 55°C temperatures and above cannot be avoided. If special precautions are taken, problems can be avoided. Solvent cements for plastic pipe contain high strength solvents, which evaporate faster at elevated temperatures. This is especially true when there is a hot wind blowing. If the pipe is stored in direct sunlight, the pipe surface temperatures may be from 10°C to 15°C higher than the ambient temperature. Solvents attack these hot surfaces faster and deeper, especially inside a joint. Therefore, it is very important to avoid puddling the cement inside the fitting socket and to wipe off any excess cement outside the joint. By following our standard instructions and using a little extra care, as outlined below, successful solvent cemented joints can be made in even the most extreme hot weather conditions.
Tips to Follow when Solvent Cementing in High Temperatures:
- Store DISHA solvent cements in a cool or shaded area prior to use.
- If possible, store fittings and pipe or at least the ends to be solvent welded, in a shady area before cementing.
- Cool surfaces to be joined by wiping with a damp rag. Make sure that surface is dry prior to applying solvent cement.
- Try to do the solvent cementing in cooler morning hours.
- Make sure that both surfaces to be joined are still wet with cement when putting them together. With large size pipe, more people on the crew may be necessary.
As you know, during hot weather there can be a greater expansion-contraction factor. We suggest you follow the advice of the pipe manufacturer regarding this condition. By using DISHA products as recommended and by following these hot weather tips, making strong, leak proof joints even during very hot weather conditions can be achieved.
For over 40 years, millions of solvent-cemented joints have been made with only rare cases of mishap. However, since flammable and toxic solvents are part of these products, appropriate safety precautions should be used.
All solvent cements and primers for plastic pipe are flammable and should not be used or stored near heat, sparks, open flames or other sources of ignition. Vapors may ignite explosively. Solvent cement vapors are heavier than air and may travel to sources of ignition at or near ground or lower levels and flash back. Keep containers closed when not in use and covered as much as possible when in use. Use in well ventilated areas. If applied in confined or partially enclosed spaces, use forced ventilation or GOVT. approved respirator. Avoid breathing vapors. Atmospheric concentration levels should be maintained below established exposure limits contained in the product’s Material Safety Data Sheet (MSDS). If airborne concentrations exceed those limits, use of a GOVT. approved organic vapor cartridge with full face piece is recommended. The effectiveness of an air-purifying respirator is limited. Use it only for a single, short-term exposure. For emergency and other conditions where short-term exposure guidelines may be exceeded, use an approved positive pressure self-contained breathing apparatus. Do not smoke, eat or drink when using these products. Avoid contact with skin, eyes and clothing. Wash clothing if contaminated and before reuse. Unprotected use may cause eye injury. Protective equipment such as gloves, goggles and impervious apron should be used. Keep out of reach of children. Carefully read our Material Safety Data Sheets and follow all precautions.
FIRST AID
Inhalation: If ill effects occur from inhalation, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Call a physician.
Eye Contact: Flush abundantly with flowing water for 15 minutes and call a physician.
Skin Contact: Wash skin with plenty of soap and water for at least 15 minutes. If irritation develops, get medical attention.
Ingestion: If swallowed give 1 to 2 glasses of water or milk, DO NOT INDUCE VOMITING. Contact physician immediately.
SPECIAL PRECAUTIONS
DISHA SOLVENT CEMENTS MUST NEVER BE USED IN A PVC OR
UPVC SYSTEM USING OR BEING TESTED BY COMPRESSED AIR OR GASES!
NOTE: Pressurized (compressed) air or other compressed gases contain large amounts of stored energy which present serious safety hazards should a system fail for any reason.
STORAGE AND HANDLING
Store in the shade between 10°C and 50°C or as specified on label. Keep away from heat, spark, open flame and other sources of ignition. Keep container closed when not in use. If the unopened container is subjected to freezing, it may become extremely thick or gelled. This cement can be placed in a warm area, where after a period of time, it will return to its original, usable condition. But such is not the case when gelation has taken place because of actual solvent loss — for example, when the container was left open too long during use or not properly sealed after use. Cement in this condition should not be used and should be properly discarded.
DISHA solvent cements are formulated to be used “as received” in original containers. Adding thinners or primers to change viscosity is not recommended. If the cement is found to be jelly-like and not free flowing, it should not be used.
USE CAUTION WITH WELDING TORCHES
At construction sites where plastic pipe is being installed or has recently been solvent welded, extreme caution should be taken when using welding torches or other equipment where sparks may be involved. Flammable vapors from cemented joints sometimes linger within or around a piping system for some time.