Conflicting standards create potential dangers

BY BILL MORRIS SPECIAL TO CONTRACTOR IMAGINE TRYING TO referee a football game with two sets of rulebooks. One rulebook says a receiver needs to have both feet inbounds to make a catch; the other says he needs just one foot. When a receiver catches a ball with one foot inbounds, what's the referee supposed to do? He'll be violating one of the rulebooks no matter what call he makes. In effect, that's

BY BILL MORRIS
SPECIAL TO CONTRACTOR

IMAGINE TRYING TO referee a football game with two sets of rulebooks. One rulebook says a receiver needs to have both feet inbounds to make a catch; the other says he needs just one foot. When a receiver catches a ball with one foot inbounds, what's the referee supposed to do? He'll be violating one of the rulebooks no matter what call he makes.

In effect, that's what plumbing code officials in International Plumbing Code jurisdictions have to deal with when they try to follow the 2003 version of the International Plumbing or International Residential Code.

Many code officials don't know it, but the codes now contain multiple ABS and PVC drain, waste, and vent pipe and fittings standards that contradict one another. The contradictions aren't trivial. They affect the safety and soundness of pipe and fittings on many construction projects.

The confusion comes from differencesin certain standards of the American-Society for Testing and Materials compared with those from the Canadian Standards Association. In recent years, there has been a drive to adopt CSA standards into the International Plumbing and Residential codes. Many of these CSA standards are excellent. Unfortunately, in some cases, these standards contradict the ASTM standards that are widely referenced in the code.

A code official attempting to use both sets of standards to approve an installation would find it impossible to make a decision because in many cases, it's impossible to satisfy one standard without violating the other. Let's examine some of the critical contradictions:

  • Prohibited joints. Section 4.14.2.2 of CSA B181.2 permits transitioning of PVC to ABS materials. This is a practice clearly prohibited in the IPC (707.1) and IRC. This would result in an unenforceable conflict for code officials.
  • Cell class (defining properties of raw materials). CSA B181.2 requires PVC compound to be light gray and conform with a cell class of 12454-B, 12454-C or 14333-D. ASTM D 2665 requires the pipe to be made of virgin PVC compounds conforming to a cell class of 12454. Pipe conforming to cell class 14333, as approved in the CSA standard, has a 20% lower tensile and modulus of elasticity. Lower tensile and modulus have a direct impact on the strength of the pipe above and below ground.

ASTM D 2321 is a commonly used standard for the underground installation of flexible piping systems. With a 3-ft. bury, a trench conforming to ASTM D 2321 would have an earth load of 392 lb./ft. and an AASHTO H-20 live load of 282 lb./ft., totaling 674 lb./ft. (AASHTO is the American Association of State Highway and Transportation Officials.)

With a maximum allowable ASTM D 2321 deflection of 5%, ASTM D 2665 pipe with a cell class of 12454 will withstand a beam load of 837 lb./ft. A 20% reduction in pipe strength could lead to ovalized and failed pipe.

A pipe's ability to withstand beam loading is important in both aboveand below-ground applications; above ground enables the pipe to be properly suspended and below ground to resist sagging should a void form beneath the pipe. A 20% reduction in pipe strength will reduce the pipe's ability to act as a beam and could lead to sagging pipe, loss of proper fall and blockages.

  • Pipe fitting and color. CSA B 181.2 requires PVC pipe and fittings to be light gray. In IPC/IRC jurisdictions, the convention is to use gray to identify electrical conduit and white for PVC DWV systems. Mistakenly cutting into electrical conduit could have far more significant consequences than cutting into a DWV line. This could pose a health and safety threat that extends well beyond the plumbing community.
  • Dimensional requirements. CSA B 181.2 and B 181.1 permit more compact short-pattern fittings as opposed to the standard weight and dimension fittings (ASTM D 3311) commonly used in IPC/IRC jurisdictions. Shortpattern fittings may be more prone to blockages especially in combination with low-flow water closets. Low-flow water closets are not in common use in jurisdictions where CSA short-pattern fittings are commonly used. Also, comingling of short-pattern fittings with fittings of standard weight and dimension might result in missed elevations and blockages.

    Cement color. CSA B 181.1 requires lemon-yellow cement on ABS pipe and fittings. IPC 605.16.2 requires that CPVC one-step cement be "yellow in color." The dual use of yellow cement for ABS as well as CPVC pipe and fittings will make it impossible for a code official to determine if the correct cement has been used. Failure to use the correct cement in either ABS or CPVC systems may result in failures. CSA B 181.1 and 181.2 also require lower minimum solvent cement viscosities than permitted in the parallel ASTM standards.

  • Cleanouts. The IPC's 705.14.3 requires that cleanout plugs be sealed with thread lubricant or tape. Sections 4.8.5 of CSA B 181.1 and 4.8.2 of B181.2 prohibit thread lubricant or sealant. This results in an unenforceable conflict for code officials. Additionally, 4.8.2 of the CSA of B 181.2 permits ACME screw threads conforming to ANSI/ ASME Standard B1.5. ACME screw threads are not permitted in the IPC or IRC. A property owner could have great difficulty in obtaining a replacement cleanout plug with an ACME screw thread that is not approved or widely available in ICC jurisdictions. This could lead to improperly matched cleanout plugs being forced into clean-out fittings resulting in a health and safety hazard.

I hope that contradictions in the plumbing code will be resolved through the ICC public comment process. Otherwise, like the unfortunate football referee mentioned earlier, plumbing code officials won't be able to ensure that we're all playing by the same rules. And a lot more is riding on their decisions than the outcome of a game.

Bill Morris is technical services manager for Charlotte Pipe and Foundry Co. He has more than 20 years of experience in the plumbing industry and is a voting member of a number of codes and standards bodies, including the ASTM A-04 Committee on Iron Castings, the IAPMO Advisory Council, the NSF Industry Forum on Standard 14, CSA B602, CSA B70 and the Cast Iron Soil Pipe Institute Technical Committee.