The 4-day technology fair also included a variety of seminars, with topics of interest to the different industries and sectors represented in the exhibit. JGSPC sponsored one such seminar during the first day entitled “PE 80 Resin + PS Mark = PE 80 Pipe Quality Assurance”. The seminar, facilitated by our manager for Product R & D and Technical Service (PRDTS) Ms. Elsie David, addressed concerns of pipe manufacturers and users on quality of HDPE pressure rated pipes.

The talk stressed the importance of the PS Mark in HDPE pressure rated pipes. Presence of the PS mark in a pipe means that (1) the pipe manufacturer is certified to QMS ISO 9001:2000, and (2) pipes submitted by the manufacturer to the BPS for certification passed PNS ISO 4427, the Philippines’ governing industry standard for PE pipes for potable water. Also discussed were the major causes of HDPE pipe failures and their effects on various properties and aspects of the pipe - mechanical, thermal, chemical and ageing. Said causes of failures were practically categorized as either (1) unrelated to PNS ISO 4427 or (2) preventable thru compliance with PNS ISO 4427.

Non-PNS related causes of HDPE pipe failures are:
(1) insufficient design, (2) inappropriate storage, handling and installation, (3) third-party damage, and (4) unfavorable service conditions. On the other hand, pipe failure causes which can be eliminated thru compliance with PNS ISO 4427 are (1) material deficiencies, (2) processing, and (3) deterioration.

Awareness of above mentioned possible causes of HDPE pipe failures leads us to very practical ways of ensuring that HDPE pressure pipes in service will not fail prematurely. First, use a correct and sufficient design, which must consider all factors that may shorten the system’s useful life. Valid standards, guidelines and computational methods must be used. Second, ensure appropriate storage, handling and transport so that premature material ageing does not occur due to UV effects, and likewise no storage damages nor pre-deformations occur in the pipe itself. Proper installation, connection, bedding condition, and prediction of loading conditions must be ensured so that pipe weaknesses are absent during its early life.

Third, third-party damages should be avoided thru ensuring that individuals and organizations carrying out excavation activities near the pipelines are properly informed of the pipe system’s existence. While the public is aware that severe damage can cause the pipeline to leak or rupture, which is a readily observable phenomenon, not everyone is aware that even minor damages to the pipe system can, over time, eventually weaken the pipeline and cause leakage and rupture. Fourth, unfavorable service conditions should be avoided, such as use of the product beyond its prescribed lifetime, insufficient controls and improper repairs.

On the other hand, elimination of those potential causes of HDPE pipe failures such as material deficiencies, processing, and deterioration can be done very simply - thru ensuring that the pipe to be used bears the PS mark. A zealous pipe end user may, on his own, even choose to have a PS mark-bearing pipe tested according to PNS ISO 4427 from time to time. If it passes the tests, then he/she is assured of having the pipe mature to its full expected life span, as long as non-PNS related potential causes are avoided.

HDPE pipe manufacturers are assured compliance of their pipes to PNS ISO 4427 thru simply but strictly adhering to three “musts”:
1. First, material deficiencies must be eliminated thru proper selection of the HDPE resin. For PE 80 pipes it must be a PE 80 rated resin such as Evalene HP10441. Correct material selection is of prime importance for safety, serviceability and durability of pipes.
2. Second, processing related potential causes of pipe failures must be eliminated. For instance, impurities must be minimized, thermal conditions during processing must be adequate to ensure proper melting and setting of the HDPE, and residual stresses must be minimized thru use of proper connections and processing conditions.
3. Lastly, the pipes must be properly protected from mechanical, chemical, biological and UV rays which can hasten the process of deterioration. For instance, HDPE pipes without carbon black should contain UV protection which sufficiently protects it from UV rays, otherwise it should only be used buried under the ground. The PNS ISO 4427 includes tests which check on the presence of such UV protection in the pipes.

PNS ISO 4427 is based on ISO 4427:1996, and includes the following major tests: (1) Thermal stability (2) Melt flow rate (3) Density (4) Hydrostatic strength (5) Longitudinal reversion, and (6) Weathering of non-black pipes.

Evalene HP10441 was certified PE 80 by Jana Laboratories of Canada. It is designed specifically for use in a wide range of pressure and non-pressure pipe applications. Elimination of the 4 non-PNS related causes of HDPE pipe failures ensures that black Evalene HP10441 pipes which bear the PS mark will provide the expected 50 years lifetime when buried under the ground.