It is common practice to pressure test installed pipelines to ensure that the pipe materials and installation are satisfactory. In fact, it makes sense that every installed pipeline be pressure tested to ensure a leak-free system.
Air valves automatically release or admit air during the filling, operation, or draining of a pipeline. For all pipe materials, efficient and safe pipeline operation is dependent on continuous removal of air from the line.
Basic discussion of the attributes of AWWA C900/C905 PVC pressure pipes.
The ASTM D2241 standard for PVC pressure pipe, first published in 1964, is marking its 50th anniversary this year. Pipe made to this standard has been widely used in both municipal and rural water markets. The standard offers a wide array of products that enable owners to design their systems for maximum economy.
Milestones from the 41-year history of AWWA PVC pipe standards.
Cyclic design for PVC pipe as provided by AWWA C900/C905 standards.
Testing requirements for AWWA PVC pipe and fittings products.
PVC pressure pipe can be installed without special backfill, since external loads are not design-limiting. For PVC gravity sewer pipe, on the other hand, backfill material and compaction are key components of design.
ISO 14000 series standards are used for environmental management, including life-cycle assessment (LCA).
To achieve a change in direction (vertical, horizontal, or a combination of both), one method is axial deflection of the gasketed pipe joints. This is appropriate where gradual changes in direction are planned without bending the pipe barrel.
Fifty years of field experience confirm that PVC pipe more than measures up to the rigors of cold-weather installation and use. In fact, an easy-to-use product like PVC pipe becomes even more advantageous as temperatures decrease. PVC is widely used in Canada, Minnesota, and the Dakotas, so cold weather is not a limiting factor for PVC pipe projects.
PPI has posted a design aid on its website that compares PE and PVC pipe. The tool, called “PACE,” has a fatal flaw, however. By restricting the design inputs to unrealistic values, PPI skews the outputs to unfavorably portray PVC.
Recent changes to AWWA standards have introduced confusion to the concepts of design factor (DF) and safety factor (SF). This document clarifies the relationship between the two terms.
Residue on pipe from diesel-truck exhaust does not justify rejection of the pipe at a jobsite.
Dimension ratio is an important but often misunderstood concept for PVC pipe. Some of the confusion arises because of the use of both "Dimension Ratio" (DR) and "Standard Dimension Ratio" (SDR) in product standards.
An examination of a University of Michigan study comparing DI and PVC pipes.
Discussion of the decline in ductile iron pipe’s flow characteristics over time.
NSF International has certified an Environmental Product Declaration (EPD) for PVC pipe.
Video inspections of PVC sewer pipelines often reveal small longitudinal gaps between the spigot end and the bell shoulder of the gasketed joints. These gaps are not flaws. In fact, gaps are an important design consideration for both pressure and non-pressure PVC pipes.
The most common thrust-restraint method in use today is external joint-restraint devices. Two types are necessary to restrain a pipe length: pipe-to-fitting restraint (usually MJ) and pipe-to-pipe restraint (bell harness).
A discussion of PVC fittings used with solid-wall and profile-wall PVC sewer pipes.
A discussion of fittings used with PVC pressure pipes.
The polyethylene pipe industry has significantly changed the way their pressure capacities are calculated. The result is thinner-walled pipes that have less pressure-resisting capability. Pipe designers should be aware of the pitfalls of specifying PE pipe.
The insertion line found on gasketed PVC pipe – marked around the pipe circumference near the spigot end – indicates the depth of insertion of the pipe spigot into the bell. The line is positioned by the pipe manufacturer based on bell design, allowances for manufacturing tolerances, and anticipated thermal expansion and contraction.
PVC sewer fittings guide – information to maximize system performance and longevity: (1) Products available; (2) Tips to optimize design; (3) Installation considerations.
A look back at AWWARF’s 1994 study on PVC water pipe performance and its findings regarding PVC pipe’s strength over time, tapping, UV exposure, chemical permeation, etc.
Installation of PVC pipe into mechanical joint (MJ) appurtenances is a very common occurrence in North American municipal pressure pipelines. Problems with MJ connections can be minimized if proper installation techniques are used.
Review of comprehensive study titled “Lessons Learned from Ductile Iron Pipe”.
A look at iron pipe’s progression to thinner and thinner walls and the subsequent corrosion issues
Joint restraint is used to prevent movement of pipe, fittings, or appurtenances in response to pressure-pipe thrust forces. Restrained joints are also necessary for trenchless installation.
Leaching of vinyl chloride monomer (VCM) into drinking water – not an issue for PVC pipe.
There are several different outside-diameter (OD) types for PVC pipe. Explanations are provided for OD types, descriptive abbreviations, and end-use applications.
Discussion of why Manning’s “n” = 0.009 for hydraulic design of PVC sewer pipe.
Product standards for PVC pipe require specific information to be continuously printed on each length of pipe. The information provides details about the pipe material, manufacture, and testing, as well as the appropriate logo of any certification agency.
“Permeation” is defined as the movement of chemicals through a pipe wall or a gasketed joint. In the last 40+ years, there have been many research projects to investigate permeation of potable-water pipes and gasketed joints. A look at the results of some of that research and why permeation is not a problem for PVC and is a major issue for HDPE.
Some specifiers choose Ductile Iron pipe due to its “strength” in resisting external loads. This was true in the good old days of thick-walled DI Class pipe, but now the thinned-down walls of DI Pressure Class pipe have made PVC the stronger option.
Testing requirements for PVC materials to be used for pipe and fittings products.
The direction that a bell is positioned makes no difference hydraulically, but is important to prevent problems during pipe installation.
Some engineers mistakenly contend that PVC pipe is not suitable for deep-bury projects. The concern is that the pipe will not hold up under large earth loads. However, installations throughout North America have shown otherwise and have demonstrated that PVC pipelines perform long-term at depths of more than 40 feet.
Maximum test pressures for installed PVC pressure pipelines.
Four joining options for trenchless installation of PVC pipe: internally restrained gasketed joints, ring-and-pin gasketed joints spline-lock gasketed joints, and butt-fused PVC joints.
Product standards for PVC municipal pipes require that the PVC materials meet ASTM D1784 cell-class requirements. The cell class consists of five numbers – this tech brief discusses the concept of cell class and what the numbers mean.
Some pipeline designers mistakenly contend that PVC pipe must be DR18 or thicker to resist collapse due to vacuum caused by fire-flow conditions. This technical brief refutes that misconception.
Discussion of the suitability of PVC pressure pipe for use under roads.
The term “large-diameter” is not well-defined – in fact, what was considered a large PVC pressure pipe has changed over the years. The attached tech brief provides clarification on the topic.
Opponents of plastic pipe materials have alleged that PVC pipe "loses strength with time" or "degrades over time." However, this is not the case – there is no degradation or loss as time passes.
Lead-poisoning is a topic of critical concern to water utilities. The good news is that lead cannot leach from PVC pipe, because there is no lead in PVC pipe raw materials or processing.
PVC pressure pipe has seen a steady increase in market share over the last 50 years. The reasons why so many water utilities have made the move to PVC pipe are discussed.
Safety considerations for low-pressure air-testing of PVC sewer pipe.
The 1.6 SF proposed for C906 falls outside the conservative tradition for AWWA standards for transmission/distribution pipe that has served North American utilities well. The PVC Pipe Association recommends that design engineers recognize this disparity and continue to use a SF = 2.0 for their projects.
When AWWA C905 pipe is used for gravity applications, one of the field acceptance tests is pulling a deflection mandrel through the installed pipeline. This document provides the method for sizing of deflection mandrels and includes a table for mandrel sizes for all C905 products.
The term “large-diameter” is not well-defined – in fact, what was considered a large PVC sewer pipe has changed over the years. The attached tech brief provides clarification on the topic.
Discussion of different joint types for storm-drainage pipe – soil-tight, silt-tight, and watertight.
"Strength” is usually a positive quality, but sometimes too much strength can cause unforeseen consequences. A case in point: ductile iron pipe’s high modulus can generate very large surge pressures in municipal water systems – pressures that may cause damage to non-pipe components.
Allegations that AWWA standards permit leaking joints are not correct. The truth is that gasketed PVC pipe joints are watertight.
Whenever there is a change in flow in a pressure pipeline, thrust forces are developed. Design for restraining these forces is streamlined by using EBAA Iron’s "Restraint Length Calculator" program.
When it is necessary to transition between PVC and DI pipe, there are several considerations to keep in mind. While PVC can be inserted into DI quite easily, insertion of DI into PVC is not recommended.
An introduction to The Uni-Bell PVC Pipe Association's Guide to Understanding the AWWA C900-16 Standard.
The ASTM F679 standard has been revised to eliminate the “T1” and “T2” wall-thickness designations, yet many municipal specifications still include the “T” call-outs. The attached tech brief discusses the current standard and how project specifications can be revised to harmonize with the standard.
Ultraviolet (UV) radiation from sunlight can affect the outermost surface of PVC pipe. However, even after prolonged exposure, there are no practical effect on PVC pipe’s performance characteristics.
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