Environmental Dynamics International

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1 Technical Bulletin 1. 4 PVC Pipe Specifications TiO 2 by: Environmental Dynamics International Published:. 5 2

2 BULLETIN BRIEF The use of PVC pipe in water and wastewater applications is a very important source of materials that are economical and give great service life. PVC pipe materials are generally specified to have UV protection by the addition of TiO 2. The history of the specification for amount of TiO 2 and the need for TiO 2 in aeration systems are somewhat divergent and it is important to present the data that has now been accumulated after many, many years of successful PVC pipe application. In the early stages of PVC pipe application, particularly in the 60 s and 70 s, there was no requirement for the addition of TiO 2 and UV protection. Studies in Australia and by the members of the Plastic Pipe Institute in the USA concluded that piping aesthetics and performance could be enhanced by the addition of small amounts of TiO 2. This TiO 2 keeps the outside surface from turning brown when exposed to sunlight as TiO 2 absorbs most of the UV and protects the body of the PVC pipe. With the early stages of PVC pipe manufacture and use, the absence of actual standards caused some variation in the way pipe was manufactured with some having no TiO 2 and some having as much as 3% percent. One aeration manufacturer was an early adopter of PVC pipe and very thin PVC pipe and settled on 2% TiO 2 which they discovered delivers excellent bright white product and eliminates browning of the pipe in exposure to sunlight. This gave a more aesthetically pleasing product and also gave some protection because they were using extremely thin PVC piping for low cost. The arbitrary PVC piping specification of 2% TiO 2 was brought to the USA and many engineers specifications on PVC pipe still carry that 2% requirement. It turns out this 2% TiO 2 was successful in meeting the diffuser manufacturers objectives, but it is not the optimum TiO 2 concentration for service. Subsequent studies have demonstrated that TiO 2 in the range of 0.5% to 2% provide the necessary performance as indicated in the Major Study of Effects of Ultraviolet Radiation on PVC Piping Publication UNI TR 5 03 by the Uni-Bell PVC Pipe Association. DISCLAIMER Environmental Dynamics International, headquartered in Columbia, Missouri, USA, presents these Technical Bulletins as a service to our customers. For more information regarding this bulletin or your specific aeration application, contact Environmental Dynamics International at +1 (573) Technical Bulletin 164 PVC Pipe Specifications TiO 2. Copyright Environmental Dynamics International 2016 All Rights Reserved

3 TECHNICAL BULLETIN 164 PVC Pipe Specifications TiO 2 Page 3 is duplicated here for the background information showing that 0.5% to 2% of TiO 2 is typically used and is the standard in the industry. This becomes important because the studies that were quite extensive over an extended period of time using SDR 35 pipe in multiple locations in the USA, as well as other studies in Australia, show that the effect of sunlight on PVC pipe is a minor deterioration in the outside surface to a depth of only This is significantly less than the allowable gouge and scuff mark tolerances which allow up to 10% of the wall thickness to be gouged and still maintain its full pressure rating. These studies also concluded that the actual strength of the PVC pipe from exposure was an average of 108% greater strength after the 2 year exposure than the standards for the strength and performance of the pipe. The Australia studies for maximum exposure conditions show 1.5% TiO 2 is sufficient to protect PVC. NO SIGNIFICANT ADVANTAGE for HIGHER TiO 2 CONCENTRATIONS in PVC PIPE. One can conclude that use of very thin pipe with damage is certainly more vulnerable than that 0.002" damage on schedule 40 or SDR 26 piping which is used by EDI in its system designs. Traditional engineer diffuser specifications have consistently shown 2% TiO 2 as the minimum requirement for diffuser piping or diffuser components used in wastewater treatment plants. This was an arbitrary value selected before standards were established.this is an arbitrary value that is a special TiO 2 concentration as there are no standard pipe manufacturers in the USA using the 2% TiO 2 as a minimum as is currently specified. This means that any PVC pipe with 2% TiO 2 will be a special run PVC pipe and will be more expensive for everyone except the vendor that standardized on that many years ago and has a pipe supplier which will manufacture that product with the 2% minimum TiO 2. The Plastic Pipe Institute does not recommend 2% TiO 2. It consistently indicates that 0.5% to 1.5% is satisfactory for the service and allows the use of standard PVC piping from all manufacturers and a more economical system for the customer. The use of DR 26 or schedule 40 piping by EDI basically eliminates the UV activity as a source of operational issues for piping systems in EDI Aeration Systems! It should be noted that systems that specify 2% as a minimum TiO2 have no technical basis for demanding the full 2% TiO2 i.e., a special content above concentration required by the Plastic Pipe Institute. It is clear that the use of TiO2 is an aesthetic item that improves the look of the system but has no impact on the actual system performance as PVC piping is generally buried or under sewage in most of the operating plans except for periods of maintenance. 2 Technical Bulletin 164 PVC Pipe Specifications TiO 2. Copyright Environmental Dynamics International 2016 All Rights Reserved

4 Conclusions: 1.TiO 2 is a valuable additive to PVC pipe for maintaining its bright color and aesthetic appearance while on the yard or prior to being installed. 2.TiO 2 does offer some UV protection; however, the protection is of nominal value when heavy wall SDR 26 or schedule 40 piping is used in diffuser systems for proper structural and functional performance in the basins. 3.The depth of UV effect is after 2 years of direct sunlight exposure. This is less than the impact of scratches and gouges on the pipe performance and UV have been demonstrated to have NO effect on the functional features of the pipe when adequate wall thickness is employed. 4.TiO 2 concentrations of minimum 2% are specialty items that were established many years ago before studies were conducted to determine the optimum amounts of TiO 2 to be employed. 5.Specification of 2% minimum TiO 2 is a proprietary specification that favors 1 vendor of aeration mixing equipment. Other vendors can obtain this specialty PVC piping only at a premium cost. 6.EDI heavy wall piping and the standard PVC Pipe Institute standards of TiO 2 are supplied on all projects and have demonstrated superior long term performance compared to thin wall pipe used by the competitors at a 2% TiO 2 concentration. Engineers should review their aeration and diffuser specifications and incorporate the use of standard PVC piping for the industry that has been studied and established with 0.5% to 1.5% TiO2 as the proper concentration to meet the objectives for pipe protection and maintenance of aesthetic appeal in service. Reference: 1.PIPA PVC Technical Information Bulletin TN006. (Plastic Pipe Institute of Australia) 2.PVC Pipe Association Technical Brief. 3.The Effects of UV Radiation on PVC Pipe UNI-TR-5-03 Uni-Bell PVC Pipe Association. 4.PPI PVC Range of Composition tech paper TR 2/ Technical Bulletin 164 PVC Pipe Specifications TiO 2. Copyright Environmental Dynamics International 2016 All Rights Reserved

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