By Amanda Hill PVC is an exceptionally durable material that has a low rate of failure. In fact, the failure rate of this material is so low that, when failures occur, it is almost always the result of poor installation or usage practices. To ensure that your crew is not contributing to failure of the PVC Read more
Pipes, Valves, & Fittings
By Amanda Hill
PVC is an exceptionally durable material that has a low rate of failure. In fact, the failure rate of this material is so low that, when failures occur, it is almost always the result of poor installation or usage practices. To ensure that your crew is not contributing to failure of the PVC and CPVC pipes you work with, make sure you are aware of these potential problems.
Improper Installation or Engineering
If the system is not properly planned or installed, the pipe could fail. One common problem is the use of too much cement to bond a pipe to a fitting. The porous PVC will absorb the cement, and an excessive amount breaks down the integrity of the pipe. The cement also allows more water to be absorbed, which can hurt the integrity of the pipe. Insufficient cement use will also be problematic, as it makes the bond too weak. Use enough cement to create a complete bond on the inside of the fitting and the outside of the pipe, but not enough that it pools in large amounts.
If the installation requires you to cut the pipe, make sure that you do not create any residue on the end of the pipe. If you see any burrs or other problems, remove them. Also, smooth the sharp outer edge of the pipe. These faults can make it difficult for the cement to bond with the pipe, leading to pipe failure. Short insertion is another type of installation error. When installing a pipe into a fitting, make sure you push it all the way to the stop. If you don’t, the gap will allow contaminants to accumulate and the pipe system will fail.
Engineering of the system can also be at fault. For example, PVC has a high coefficient of linear thermal expansion and needs room to expand when temperatures fluctuate. Expansion loops or roller hangers can help eliminate this problem. Using a qualified system engineer will also ensure that the system is designed to account for expansion. Similarly, the pipe must be installed so that it does not have excessive bending deflection. This will lead to both pipe and fitting failure, as it places too much stress on the plastic. Pipes need to be installed into fittings in the proper alignment to avoid this problem.
Improper Use of System
PVC is incredibly strong when used properly. However, improper operation of the system will lead to failure. For example, exposing the system to freezing temperatures without proper freeze protection is a recipe for failure. Filling the pipes with glycerin solution can help. Over-pressurization of the system is another problem. Be certain the system uses the proper schedule of PVC for the amount of pressure you will be placing on it.
Sometimes the system will be set up so that conduit bends around the PVC pipe. This places stress on the PVC at the point of contact with the conduit. This can also cause the conduit to fail and should be completely avoided.
Contamination of the System
For external contamination, watch for exposure to elements used in other systems that are not compatible with PVC use. For instance, PVC should never be in contact with aromatic ester plasticizers or flame retardants. These components are commonly found in fire caulk, and even a drop of the caulk that falls onto the PVC can damage the plastic and lead to failure. Similarly, black grommets, which are incompatible with PVC use, should never be used to seal any part of a PVC system. The phthalate ester plasticizers in a black grommet will damage PVC. Solder flux, polyurethane spray foam and antimicrobial linings found in steel pipes can also contaminate PVC.
PVC’s durability means it can handle many corrosive chemicals once the system is installed. Interior contamination typically happens during installation when non-approved materials are used in the PVC system. That being said, some products, like fire protection foam, should not be delivered via PVC systems, as they will cause internal contamination.
To avoid internal contamination, discuss the system with the PVC manufacturer, and only use PVC for transporting fluids it is designed to carry. If you are concerned about the product it will be carrying, ask before installing.
Manufacturing Defects
Manufacturing defects in PVC are quite rare, but they can happen. If the extrusion and cooling process is not carefully monitored and performed, defects in the pipe can lead to failure. These defects can occur because of a dirty die, which causes extrusion lines or improper cooling, which cause stresses throughout the pipe. When pipes are frozen with stresses from the manufacturing process, they react like coiled springs seeking a way to relieve that stress. While you can’t avoid this problem entirely, working with a trusted manufacturer can help.
Defects in the Resin
The resin used to create PVC and CPVC pipes must be carefully mixed to avoid defects. If the filler content is wrong, the pipe will not be as strong as it should be. Similarly, if the chlorine content is wrong in a CPVC pipe, it will not be able to withstand normal operating pressures. Additives or pigments that are added in the wrong way can also cause problems. Again, using a quality distributor and manufacturer you trust can help limit these issues.
Distributor Abuse
PVC should not be stored in direct sunlight for extended periods of time. While the material should be strong enough to withstand repeated exposure to the elements, lengthy storage in this way could damage its integrity. Also, if the PVC is damaged in transport, it can lead to pipe failure. Buy your PVC from a supplier you trust, and inspect every pipe thoroughly before putting it into the system to avoid this problem.
Careful installation, using the right distributor and manufacturer, and avoiding contamination issues are the keys to preventing pipe failure in your PVC systems. Pay careful attention to these areas, and your systems should remain strong for years.
Author Bio:
Amanda Hill is the Content Manager for CIS (Commerical Industrial Supply), a supplier of PVC pipes, fittings, and other accessories for plumbing professionals all across the country.
Matco-Norca offers no hub couplings in both standard and heavy-duty versions for use in joining hubless cast iron pipe applications. Both Standard and Heavy-Duty Couplings provide ease of installation and permanent sealing solutions as well as proper pipe alignment. Matco-Norca 452 Series Standard No Hub Couplings are UPC and IPC approved and conform to the Read more
Matco-Norca offers no hub couplings in both standard and heavy-duty versions for use in joining hubless cast iron pipe applications. Both Standard and Heavy-Duty Couplings provide ease of installation and permanent sealing solutions as well as proper pipe alignment.
Matco-Norca 452 Series Standard No Hub Couplings are UPC and IPC approved and conform to the latest editions of ASTM C1277/C564. They are available in sizes 1-1/2” through 10”. Sizes 1-1/2” – 4” contain two Type 310 stainless steel bands standard (with 4 bands available upon request); sizes 5”-10” come with 4 bands standard (with 6 bands available upon request) 452 Series Standard No Hub Couplings come with a neoprene gasket to provide a cushioning element in the joint to absorb shock and vibration, assuring a quiet, trouble-fee operating plumbing system.
452 Series Heavy-Duty (H) No Hub Couplings, available in sizes 2” – 10”, consist of a neoprene rubber gasket (compliant with ASTM C564 requirements) and a heavy gauge stainless steel (300 series) clamp assembly. 452H Series Couplings are available with four or six bands (depending on the coupling size) and feature specially designed bi-directional eyelets.
452H Series Couplings’ metal components meet or exceed ASTM C1540-C564 requirements for heavy-duty shielded couplings joining hubless cast iron soil pipe and fittings.
Chicago Faucets expands the selection of pressure-balancing tub and shower fittings with a new valve that incorporates several significant updates to match unique needs, design and budget for every application. The new tub and shower fittings are ideal for education, healthcare, hospitality, multi-family and fitness applications. With its finely tuned ceramic operating cartridge, the new Read more
Chicago Faucets expands the selection of pressure-balancing tub and shower fittings with a new valve that incorporates several significant updates to match unique needs, design and budget for every application. The new tub and shower fittings are ideal for education, healthcare, hospitality, multi-family and fitness applications.
With its finely tuned ceramic operating cartridge, the new Chicago Faucets pressure-balancing shower valve offers improved flow management, precise hot- and cold-water mixing, simplified hot water volume adjustment, and a reduced flow rate (GPM) for both tub and shower service. Hot and cold supply inlet check stops are built into every valve. The complete fittings feature modern wall trim styling, with a polished chrome wall plate that’s dual-indexed: embossed “H” and “C” and color-coded temperature graduation allow the user to adjust temperature quickly and easily.
The new Chicago Faucets shower valve is available as part of a complete system that includes a choice of shower head, a diverter tub spout and all finishing trim. The valve may also be purchased separately. Installation is easy: valve inlets and outlets with both 1/2″ NPT and copper sweat connections are built in. All Chicago Faucets tub and shower fittings are fully compliant with relevant plumbing codes and standards. More information on these products can be found at www.chicagofaucets.com or by calling 800-566-2100.
The Chicago Faucet Company is part of the Geberit Group, a European market leader and global provider of sanitary technology. Since 1901, The Chicago Faucet Company, located in Des Plaines, Illinois, has offered commercial and residential products built to stand the test of time. A combination of the best engineering, finest materials and quality workmanship has made Chicago Faucets the specified choice in many of the finest building projects throughout North America.
As European market leader, the Geberit Group is a global provider in the area of plumbing technology with sales of CHF 2.3 billion and about 6,200 employees in 41 countries worldwide.
Cast Iron Piping Benefits By Francesca Dunbar We have to make choices every day. Personal preference seems to dominate over objective reasoning and we get complacent in our decision making. When it comes to drain, waste and vent (DWV) plumbing systems there is an ongoing debate over which is a better solution, iron or plastic. Read more
Cast Iron Piping Benefits
By Francesca Dunbar
We have to make choices every day. Personal preference seems to dominate over objective reasoning and we get complacent in our decision making. When it comes to drain, waste and vent (DWV) plumbing systems there is an ongoing debate over which is a better solution, iron or plastic. Both products have their advantages and disadvantages. Designers and contractors are experiencing tremendous pressure to value engineer projects. Most builders are not willing to give up features in their design to bring the project costs down and look to cut corners on building materials to help reduce the overall project cost. These value engineered tradeoffs are typically not seen until a building is occupied.
Life Safety – Making the Right Choice
The superiority of cast iron (CI) over polyvinyl chloride (PVC) piping in fire safety cannot be overstated. Many people who die in fires do not perish from flame or heat, but rather from the gases released during the heating and combustion of typical building materials or furnishings. Slowing or stopping the spread of these gases through aggressive firestopping is a proven life saver. Contractor and building owners today are concerned about liability.
Most experts agree that CI provides unsurpassed fire resistance. Cast iron does not burn, does not off-gas when heated to temperatures normally encountered in structure fires, it is easy to install, and has superior durability often out lasting the life of a building. This resistance to burning has the added benefit of requiring simple, low-cost firestopping between the annular space between the pipe and wall penetration. That is not the case with PVC piping where the initial cost savings are frequently offset by the added perfunctory material costs. Cast iron pipe and fittings are joined together with no-hub couplings consisting of neoprene gaskets and stainless steel shields and bands. These can be assembled or disassembled very easily.
Something else to consider if choosing PVC as it relates to fire wall penetrations. PVC is combustible and requires complex firestopping systems – each penetration between the pipe and wall infiltration must be sealed with an intumescent material. In the case of fire due to heat, PVC piping will melt away. Therefore, firestopping with intumescent product is needed to fill each and every void and penetration. This intumescent firestopping system is significantly more expensive than the simple and low-cost measures required for cast iron.
Sound Attenuation
Cast iron is often referred to as the “quiet pipetm” because of its superior noise suppression unlike PVC piping. Studies have shown CI to be a superior product in controlling noise due to its density. This makes cast iron ideal for condominiums, hotels, healthcare facilities and educational institutions. Unlike PVC, cast iron soil pipe effectively suppresses the sound of swooshing water cascading down from upstairs fixtures. This sound attenuation feature can be a major benefit in quality residential and commercial construction, where building owners and tenants understand the advantage of iron by the very first flush.
On the other hand, PVC used in drain and waste systems is noisy and annoying and often the cause of tenant frustration. If you’ve ever stayed in a hotel plumbed with PVC, you can often hear others showering and flushing toilets depriving guests from the well needed rest they desire. While plastic piping is an inexpensive material, it may not be the right product for every application. The problem with PVC pipe in drain and waste systems is that it produces a lot of noise due to the innate properties of low density plastic and the cementing of pipe and fittings together. To combat the noisy PVC piping system one solution is to wrap the PVC pipes with a good insulating material such as fiberglass or neoprene foam jacketing. The intrinsic properties of cast iron pipe along with the separation of the pipe and fittings by the use of a gasket or coupling is highly effective in reducing the likelihood of sound traveling through the system. Don’t get me wrong, there are special applications for PVC piping, but not in drain and waste applications.
Noise Level Chart
A noise level chart showing examples of sounds with dB levels ranging from 0 to 100 decibels.
0 = Healthy hearing threshold |
30 = A voice whisper |
25 = Cast iron vertical enclosed pipes (average) |
33 = PVC vertical enclosed pipes (average) |
50 = Light traffic or sound of a refrigerator |
70 = A shower or dishwasher running |
75 = A toilet flushing or vacuum cleaner |
100 = Riding a motorcycle or operating a hand held drill |
Summary of overall noise levels in dBA emitted by cast iron and PVC pipes while evacuating a 1.6 gallon water flush test. Significant findings that cast iron pipes are quieter than PVC whether or not the pipes are enclosed. This information is based on an independent research study by MJM Acoustical Consultants, Inc.
Listen Up – Noise Pollution is a Problem
Commercial building designers and engineers need to take note of the acoustical performance of the building project and be very cautious of the potentially negative effects of value engineering. Excessive noise from plumbing systems is typically unnoticed until the building is occupied, creating ongoing problems for the occupants. Sound attenuation is regularly value engineered out of jobs, often the result of product substitutions and misguided cost cutting measures. Beware of the unexpected consequences of value engineering.
The World Health Organization (WHO) has done extensive studies in healthcare facilities and has identified noise levels around rooms at night as disruptive to patients. This is especially true in hospitals with multiple levels. These types of structures also have additional noise pollution from waste water evacuation from toilets flushing, showers and storm drains. Excessive noise can lead to sleep disruption and increased levels of stress thus hindering the healing process sought in a hospital setting.
Studies have also concluded classroom noise interferes with the ability for a teacher to educate students effectively, and students to learn. Raising the voice level provides little compensation. ANSI Standard S 12.60-2002 Design Requirements and Guidelines for Schools recommend a maximum of 35 decibels for background noise. There is a direct link between the classroom acoustic environment and the scholastic achievement of students. The result of a US Government Accounting Office survey found that 28% of the nation’s schools reported “acoustics for noise control” as their top environmental problem. This suggests that the 28% figure from this survey may be a substantial understatement of the problem of acoustic barriers in schools since a background noise level of 50 db is 15 dB above the recommended limit included in a US standard for classroom acoustics.
The attributes of cast iron when it comes to sound attenuation cannot be overlooked. Due to its sound-deadening properties, cast iron inherently has a dense molecular structure and a natural heavy mass making it the quieter solution. According to a study by Polysonics Acoustical Engineers, cast iron is 750% more effective in silencing plumbing noise when compared to PVC. With CI, sound is effectively muffled rather than transmitted, as it is with PVC pipe. Noisy PVC piping can be masked by utilizing sound-deadening insulation that is carefully installed with neoprene foam jacketing or other insulation processes but there are again added costs to even come close to the quiet CI piping.
Friend, Foe or Both?
In conclusion, so do you know which product is better, cast iron or plastic? Both products have their advantages and disadvantages, though cast iron is more environmentally friendly than plastic as it is made from ~100% post-consumer scrap iron while on the other hand, thermoplastic piping is produced using petroleum derived materials. So we go back to which product is better. Well, the answer may be to consider using both together. Plastic pipe is a great choice for the vent system since air doesn’t create vibrations and will be whisper quiet. While on the other hand using cast iron is an ideal solution for underground piping and vertical stacking of indoor pipes. This amalgamated method will benefit the occupants seeking a quiet and durable plumbing system that is a cost effective solution.
Word to the wise, consider the added costs if you choose PVC as it will require more hangers, screws, fasteners, primer, glue, additional labor costs, inspections, neoprene foam jackets to deaden sound, or insulation to muffle the noisy pipes. These supplementary costs are often overlooked when value engineering a project and can cost just as much if not more than a cast iron DWV system.
About the Author:
Francesca Dunbar is the Director of Marketing for the McWane Plumbing Group Division. She can be reached by email at Francesca.Dunbar@McWanePlbGrp.com.
Quiet Pipe is a trademark of Cast Iron Soil Pipe Institute “CISPI”.
REFERENCES
1. The Impact of Classroom Acoustics on Scholastic Achievement by Louis C. Sutherland and David Lubman, 17th Meeting of the International Commission for Acoustics, Rome, Italy, Sept. 2-7, 2001
2. Plumbing Engineer – Features: June 2012: Sound design in drain, waste and vent lines http://www.plumbingengineer.com/june_12/piping_feature.php
3. Acoustic Control LLC http://www.acousticontrol.com/hospital-acoustics.html
by plumbing expert Rich Grimes What is the best domestic water piping system? Great question with no easy answer! It is truly a matter of preference and each system has its own inherent benefits. Let’s look at some of the more common materials that are used. Most products up to 2″ size are Copper Tube Read more
by plumbing expert Rich Grimes
What is the best domestic water piping system? Great question with no easy answer! It is truly a matter of preference and each system has its own inherent benefits. Let’s look at some of the more common materials that are used. Most products up to 2″ size are Copper Tube Size (CTS) but alternative methods can be Iron Pipe Size (IPS). The key is that products must be NSF-61 listed for potable water.
COPPER is one of the oldest and most reliable methods for domestic water supplies. It has become an expensive metal over time so that opens the door for alternative piping systems. It has various benefits such as strength, corrosion and temperature resistance, longevity and its natural ability to inhibit bacterial growth. It uses full-flow fittings (tube fits inside of fitting) that are typically soldered connections.
CPVC is another CTS piping material that is often used for domestic water. It is a harder version of PVC that can withstand temperatures up to 180F. It employs a full-flow fitting that is usually socket-welded with solvent-cement. It is non-metallic so it can answer some issues that may arise with copper (dielectric corrosion, etc.) but it is a polymer that can degrade when exposed to petroleum and other chemical products. While it is mostly sold up to 2″ size in CTS, it also is sold as a Schedule 40 or 80 IPS potable water distribution system.
PEX is another polymer that is rated for domestic potable water. It is also CTS size tubing with an internal fitting. It uses a crimp-ring or clamp around the tubing and fitting to create a joint. Crimp and clamp tools are an integral part of the system for making a watertight connection. PEX is a flexible, labor-saving product that is produced in long coils. Long runs can be accomplished with fewer fittings or no fittings under slab.
There are several other polymers that have a NSF-61 rating, typically in IPS and used on domestic water lines over 2″ size. These are competing with large diameter metal piping systems for CW and HW mains of copper or SS.
One variable that must considered is the fittings to be used and the joining method. Today there are a variety of specialty fittings that can greatly reduce installation time and labor. While these fittings and joining methods may have a higher fitting cost, they can ultimately save money when considering the total installed cost. Press fittings have become popular because they greatly reduce labor and allow for a viable copper joint. Solvent welded CPVC can save labor over a soldered copper connection but there are solvent cement costs and joint curing times that must be considered. PEX fittings cost more that CPVC fittings but their clamping methods reduce labor and there is no waiting for curing. A mechanically-extracted tee on copper can eliminate most fitting costs and greatly reduce labor, but they require brazed joints and the cost of the tool system comes into play. Push-joint fittings eliminate tool costs, soldering or solvent-welding, down time, and labor but the fitting cost is higher…
It is probably best to look at items like project location, type of service, local environment, operating temperatures, ambient temperatures, tubing heat transfer, etc. to select the right piping or tubing for a project. Most contractors will utilize several if not all of these methods in their business, but typically standardize on a preferred pipe and fitting method. There is no single piping system that can meet every need and each system has its own benefits and best application. As well, each system is not bulletproof and can be susceptible to the surrounding environment, chemicals or various stresses that can cause a failure. Most products today have very high pressure ratings and it is proven that most piping failures are due to improper preparation and installation. If the manufacturer’s instructions are followed, any of these piping methods can provide a good domestic water distribution system that will last for years and years.