- Category: Industry Matters
- Published on 01 July 2016
- Hits: 383
By Rory Macnamara.
Too much time has passed since discussions started on SANS 721:2014, which was published without consideration for the genuine concerns of both the technical committee and sub committees. Subsequently, the South African Bureau of Standards, or SABS, appointed an independent assessor to assess the standard after it had been approved and published. A copy of the assessor’s report is in Plumbing Africa’s possession.
We have delayed publishing summaries of the findings in the hope that the SABS would have met with the relevant parties and issued a release detailing the outcomes. The assessor delivered the report at the end of November 2015 and it was distributed to the committees in March 2016. Since then, committee meetings have been planned; yet not one has taken place.
The SABS and their parent the Department of Trade and Industry have not dealt with this matter promptly. We believe our first responsibility is to our readers, and to serve them, we have decided to publish in this article a summary of sections of the report for those who may be using this pipe under this standard, in the hope it will perform as claimed in the long term. Please note it is a short summary only and does not offer a full view of issues such as diameter range and standard dimension range.
Description of standards
For completeness, the description of the standard is: Polypropylene (PP) pipes and pipe fittings for soil, waste and vent (SWV) applications for above-ground use. The brief to the assessor was to:
- Review the technical arguments as submitted by the appeal to SANS 721, and provide a detailed report based on the evaluation of SANS 721, its normative references and its fit for purpose;
- Provide research data on the stability of polypropylene for above-ground application with regard to SANS 721;
- Interview the appellant and the affected party independently on the appeal to SANS 721; and
- Provide a recommendation to the SABS on the way forward regarding the published SANS 721.
This standard was controversial from the start, because for PP to be used in above-ground applications it must be stabilised to withstand long-term weathering. This process is commonly referred to as ‘carbon black’ and PP must have the appropriate carbon black content or some UV stabiliser.
Technical committees and sub-committees, consisting of industry professionals who freely offer their time for standards to be correctly and intelligently drawn up, have opposed this standard in its current form from the start.
Sections from the executive summary of the assessor’s report are as follows:
“It is concluded SANS 721 has a number of deficiencies” and “The references to SANS 8773 are inadequate and/or inappropriate.” The assessor goes on to state that “SANS 8773 is intended for applications where the products are not exposed to direct sunlight, so the performance requirements are predicated on this.” “SANS 721 does not adequately address long-term weathering. The weathering test taken from SANS 967 does not provide any assurance at all as to the ability of SWV products to withstand the long-term weathering expected when installed in exposed locations. “Requiring PP pipe and fittings intended for outdoor installation to have the appropriate carbon black content would provide a technical solution to the weathering problem. Alternatively, a combination of organic UV stabilisers (HALS) and a suitable concentration of rutile titanium dioxide might provide adequate protection, but this would have to be demonstrated by performing long-term accelerated testing.”
“SANS 721 appears to be an amalgamation of SANS 967 and SANS ISO 8773, with many cross references to the latter. This makes the document difficult to follow.
UV – weather resistance
The pass-fail criteria for the UV resistance test in clause 4.4 of SANS 721 are entirely subjective. The requirement is that there shall be no sign of “discolouration, cracking or other deleterious defects. However, there is no guidance on how to assess for possible discolouration or cracking, nor any indication as to what should be considered a deleterious defect.”
The assessor follows with a detailed explanation of the various references and indications of lifespan, testing and the type of tests for different applications. The telling point is, “The Plastic Pipes Institute in the US has published a technical note that includes the following statement: ‘Non-black PP pipe should not be installed above-ground outdoors where it would be continuously exposed to ultraviolet light or sunlight.’”
Concerning weathering, which is critical in South Africa considering the high sun volumes we have, the assessor’s recommendation is: “For SANS 721, consideration should be given to upgrading the UV test to make it a true assessment of longevity in exposed applications. The alternative to the weathering test would be the addition of carbon black.”
We have a standard that is either both incomplete and incompetent, or we have undue political pressure being brought to bear on committees. SANS 721 cannot offer any comfort to users in its current form and has the potential not to deliver on manufacturer’s claims, that is, those manufacturers that choose to use SANS 721 instead of SANS 8773 — plastic piping systems for non-pressure underground drainage and sewerage.
It is sad that a meeting has not been arranged to resolve this matter while unsuspecting buyers are spending money on a product that, very likely, will not deliver as is required in terms of longevity and reliability.