Y o u r V a l u e P a r t n e r. Quality. Without COMPROMISE

Size: px

Start display at page:

Download "Y o u r V a l u e P a r t n e r. Quality. Without COMPROMISE"

Abner Welch
6 years ago
Views:

1 Y o u r V a l u e P a r t n e r Quality Without COMPROMISE

2 1 What is the Cost of Quality Compromise? In an economic society where most commodities are designed to sell, not to last the reality is that, in order to provide the lowest price and remain competitive, quality is often compromised in favour of lower costs. As a result, products that cut corners in the manufacturing process or that contain inferior materials - although less expensive - can come with hidden costs that often fall to the customer. While this applies to many industries, the manufacture of plastic products, with specific reference to plastic pipes and fittings, offer an insightful look into this dilemma and highlights the costs that incur as a result of this quality compromise, both financial and in terms of the health and safety of our communities and the environment. A well-engineered pipe system is not only dependent on good design however, as strict adherence to quality standards is of critical importance throughout the value chain, from raw material selection through to the fabrication and installation of the pipelines that make up our country s infrastructure. Marley's mandate on quality assurance At Marley, we have a no-compromise mandate on quality; our ongoing commitment to a policy of total quality management guarantees that all products and services meet the highest requirements, and we strive to continuously improve our products and operational processes as well as increase efficiency, reduce waste and save money. Our Quality Assurance policy includes a commitment to: Delivering superior piping solutions with quality workmanship and excellent service capabilities Constant improvement of a quality culture across all business operations Guaranteed quality assurance in accordance with customer requirements and industry standards Compliance with best professional practice in health, safety and environment Satisfying customer demands for world-class quality, timely delivery and competitive pricing Full traceability of all components and process from cradle to grave This Quality Without Compromise is the cornerstone of our reputation, and the reason why we are recognised as the market leader in reliable pipe systems across sub-saharan Africa today. Each stage of production, from raw material selection to warehousing and distribution, as well as testing methods, conform to strict quality controls based on the SANS ISO9001:2008 Quality Management System and products manufactured under this system carry the relevant SABS marks, as per the respective permits.

2 Compromise in the quality of raw materials 85% of polethylene (PE) pipe system failures are due to the use of non-conforming recycled materials in production 80% Raw material composition of PE pipe

material (regrind) from external suppliers.

3 2 Compromise in the quality of raw materials 85% of polethylene (PE) pipe system failures are due to the use of non-conforming recycled materials in production 80% Raw material composition of PE pipe Control of quality of the raw material mix is essential for compliance with specified requirements of the finished product Manufacturers that compromise on quality over cost often source reworked material (regrind) from external suppliers. Although studies show that reworked material itself is not inherently unsafe, the use of a significant amount of regrind material of which the origin of the raw materials is unknown poses a risk of contamination and impurities, thereby lowering the overall quality of the pipe which could cost you in the long run. SANS paragraph 4.3 Clean, reprocessable material generated from a manufacturer s own production and works testing of products according to ISO 4427 may be used if it is derived from the same compound as used for the relevant production. Reprocessable material obtained from external sources and recyclable material shall not be used. Effects of non-conformance on the quality of pipe systems: A case study In the investigation of HDPE pipe failures which occurred in various areas of a site in Bloemfontein, pipes were collected and analysed. These were the results: Pipe 1 (Markings: 32mm PE100 PN10 SANS ISO 4427:2008) Pipe 2 (No Markings) Pipe 3 (Markings: SABS Approved SAPPMA) Test Dimensions Min. Wall Thickness Max. Wall Thickness Ovality Carbon Black Content Test Dimensions Min. Wall Thickness Max. Wall Thickness Ovality Carbon Black Content Test Dimensions Min. Wall Thickness Max. Wall Thickness Ovality Carbon Black Content Result Requirement (ISO 4427) Comment 1.59mm 2.05mm 1.3mm 2.96% mm mm 1.3mm 2-2.5% Non-conformance Non-conformance Result Requirement (ISO 4427) Comment 3.00mm mm Non-conformance 3.37mm mm Non-conformance 1.0mm 1.3mm 1.33% 2-2.5% Non-conformance Result Requirement (ISO 4427) Comment 2.09mm mm 2.30mm mm 1.3mm 1.3mm 2.45% 2-2.5% Marley Pipe Systems makes use of 100% premium quality virgin materials in the production of PE pipe, resulting in a finished product that is safe, and that meets both our company standards as well as regulatory requirements. TIP: Before choosing a pipe supplier, ask the manufacturer to supply you with a material certificate to verify the origin of pipes and fittings.

3 Compromise in the quality of PE pipe fittings Fully pressure rated fittings can be fabricated to at least a PN12 pressure rating The fabrication of PE pipe fittings has earned an unfavourable

In many cases, this perception has arisen as a result of customers selecting HDPE pipe solutions on the basis of cost instead of quality, resulting in poor installations and joint failures down the

4 3 Compromise in the quality of PE pipe fittings Fully pressure rated fittings can be fabricated to at least a PN12 pressure rating The fabrication of PE pipe fittings has earned an unfavourable reputation in the industry because of its perceived inferior quality. In many cases, this perception has arisen as a result of customers selecting HDPE pipe solutions on the basis of cost instead of quality, resulting in poor installations and joint failures down the line. Contractors often attribute these failures to the poor quality of the fabricated fittings, when in reality it was due to a lack of understanding in the quality of what they were purchasing. It is therefore essential for companies to be aware of and understand the design considerations and de-rating factors that affect the overall quality of fabricated fittings. DE-RATING FACTORS EXPLAINED Fabricated HDPE bend with a mitred angle that is greater than 7.5 but less than 15 (7.5 >15 ) Fabricated HDPE T-Pieces De-rating = 20% De-rating = 50% Pipeline System at 10 bar (SDR17) Bends: 12.5 bar (SDR13.6) rating T-Piece: 20 bar (SDR9) rating Maximum rating of fabricated fittings Bends: 20 bar using 25 bar (SDR7.4) pipe Tees: 12.5 bar using 25 bar (SDR7.4) rated The following has been obtained from SANS which specifies the general aspects of fittings made from polyethylene (PE) for piping systems: De-rating Factors for Segmented Bends Table B.3 Cut angle (β) 7,5 7.5 < β 15 De-rating factor (f B ) 1,0 0.8 De-rating Factors for Segmented Tees Figure B.4 For tees fabricated out of pipe segments, the following de-rating rules for the calculation of the PN shall apply: PN = f T x PN pipe where f T is the de-rating factor for these tees, having a value of 0.5; PN pipe is the nominal pressure of the pipe

4 Compromise in the quality of PE pipe fittings (Continued) Welding considerations in the manufacture of fabricated fittings 1 (P-WPS) Preliminary Welding Procedure Specification Proposed welding

and trained by an accredited training authority such as Plastics SA 3 (WPS) Welding Procedure Specification Final acceptance document that records materials, methods and practices used in the welding

5 4 Compromise in the quality of PE pipe fittings (Continued) Welding considerations in the manufacture of fabricated fittings 1 (P-WPS) Preliminary Welding Procedure Specification Proposed welding procedure specification assumed by the contractor to be adequate, before acceptance by the customer 2 Welding Personnel People who execute welded joints in thermoplastics materials must be skilled and trained by an accredited training authority such as Plastics SA 3 (WPS) Welding Procedure Specification Final acceptance document that records materials, methods and practices used in the welding of a joint 4 (WPS-WR) Welding Procedure Specification Qualification A statement of results for every qualification joint 5 Welding Process Technique used to execute a permanent joint, characterised by the welding method used Marley is committed to the fabrication of high quality pressure rated and de-rated HDPE fittings for our customer s unique requirements. At our fully-equipped workshop, our fabrication team follows a strict quality control system to ensure the accurate inspection, documentation and certification of quality which enables full traceability of our fabricated fittings from raw material stage to the final product. As a result of this quality assurance process, we are able to provide 100% void-free stubs which is confirmed through x-ray controls on each batch up to 500mm.

5 Compromise on quality specifications The plastic pipes industry centres around internationally established specifications that need to be met in order to achieve certain performance criteria as

SANS 4427 National Standard: Plastics piping systems Polyethylene (PE) pipes and fittings for water supply Even though a pipe may carry the SABS mark of approval, this does not necessarily mean that

irregularities in wall thickness along the pipe, also known as wall thickness fluctuation.

systems Pipe Crack Contamination Gels in Material Sink Marks Calculation of pipe wall thickness Given: pipe material (e.g.

6 5 Compromise on quality specifications The plastic pipes industry centres around internationally established specifications that need to be met in order to achieve certain performance criteria as well as the test methods to verify this performance. SANS 4427 National Standard: Plastics piping systems Polyethylene (PE) pipes and fittings for water supply Even though a pipe may carry the SABS mark of approval, this does not necessarily mean that it conforms to industry standards Specifies the minimum requirements that PE piping system designers need to take into account in order to ensure the quality, safety and efficiency of the products that are produced and utilised. In an attempt to cut down on costs and materials, however, some manufacturers of pipes and fittings purposefully use less material or take shortcuts in the manufacturing process, resulting in irregularities in wall thickness along the pipe, also known as wall thickness fluctuation. WALL THICKNESS FLUCTUATION CAUSE RESULT Machines are not calibrated/operated properly Heating and cooling process is not set properly Variation in throughput extrusion rates Weak points in pipe systems Pipe Crack Contamination Gels in Material Sink Marks Calculation of pipe wall thickness Given: pipe material (e.g. PE100), outside diameter of pipe, medium, stress-dependent resistance factor, operating temperature, service life, safety factor, internal pipe pressure Unknown: wall thickness of the pipe On the basis of operating temperature and service life, the admissible hoop stress σ vadm is obtained from the hydrostatic strength diagram. Wall thickness of the pipe is thus: s = d a (20.f CRσ.σ vadm ) +1 (S.ρ) where s = wall thickness of the pipe (mm) d a = outside pipe diameter (mm) f CRσ = stress-dependent resistance factor (-), for water = 1 σ vadm = admissible hoop stress from hydrostatic strength diagram (N/mm 2 or MPa) S = safety factor (-), for water pipes S min = 1.25 ρ = internal pipe pressure (bar) To minimise wall thickness fluctuation, gravimetric extrusion systems can be used to control the dimensions of the pipe during production, thereby maintaining adherence to specifications by ensuring accuracy and consistency throughout the production run. TIP: Ask your pipe supplier for proof that pipes comply with the relevant standards in the form of an SABS certificate. Take your own measurements upon receipt of goods and perform measurements after cutting a pipe

6 Compromise on quality process The overstressing of pipe material can cause premature wear and

different loads that could have potentially damaging effects to pipeline applications if not considered

Consequently, manufacturers of pipe are required by stringent codes of practice to follow specific

of the materials, thereby ensuring the safety of the piping system by verifying the structural

3 CRITICAL FACTORS OF PE PIPE PERFORMANCE High internal pressure time-to-failure (creep rupture

QUALITY CRITERIA The quality of pipes and fittings is not determined by the pipe material alone,

During pipe production Pipe materials must be stored in a silo (normally at least 1 silo for each

PE100 pipes must correspond to SANS 4427 and/or related standards.

7 6 Compromise on quality process The overstressing of pipe material can cause premature wear and breakage of the installed pipe Plastic pipes are generally subjected to many types of stress caused by different loads that could have potentially damaging effects to pipeline applications if not considered adequately. Consequently, manufacturers of pipe are required by stringent codes of practice to follow specific quality control processes which are put in place to ensure that the pipe design does not overstress any of the materials, thereby ensuring the safety of the piping system by verifying the structural integrity of the pipe against the expected loading conditions over the lifetime of the system. 3 CRITICAL FACTORS OF PE PIPE PERFORMANCE High internal pressure time-to-failure (creep rupture strength) Outstanding resistance to slow crack growth (SCG) Good resistance to rapid crack propagation QUALITY CRITERIA The quality of pipes and fittings is not determined by the pipe material alone, however, but also by the control process during pipe and fitting production. During pipe production Pipe materials must be stored in a silo (normally at least 1 silo for each standard type of pipe material) to avoid the mixture of pipe materials Dimensions and tolerance of PE100 pipes must correspond to SANS 4427 and/or related standards. In addition, continuous inline control by means of ultrasonic measuring systems can be used to detect deviations in the range. In the case of PE100 pipes for gas and drinking water applications, the use of externally sourced, non-virgin material or externally sourced regrind material should be avoided at all costs.

7 Compromise on quality process (Continued) During fittings manufacture Material used for injection moulding should be of only one type and enhanced demands should be made on flowability and thermal

8 7 Compromise on quality process (Continued) During fittings manufacture Material used for injection moulding should be of only one type and enhanced demands should be made on flowability and thermal stability of materials. The processing parameters (injection speed, level and time of back pressure) should be regulated to enable the continuous control of the adjusted parameters and the setting of tolerance limits. Gate systems should be chosen in such a way as to avoid weld lines due to irregular melt flow in the mould. TEST REQUIREMENTS A multitude of tests must be carried out during and after pipe production, from tests performed on the machines via random tests on samples to non-destructive and destructive laboratory tests. MFR Test (melt flow rate) Density Measurement Final Control X-Ray Tests (fittings) Heat Storage Tests Control of Packing Control of Overall Length Control of Marking Control of Homogeneity Optical Control of Surface Dimensional Controls Short-term Tests (internal pressure & burst tests) Determination of Thermal Stability (OIT - oxidation induction time) Long-term Tests (internal pressure & burst tests)

8 Compromise on quality process (Continued) TYPICAL PROPERTIES OF HDPE PIPE Carbon Black Dispersion Poor distribution results in stress

expected product lifespan, and physical and mechanical properties Circumferential & Dimensional Irregularities Results in pipe failure

sealability of pipes and fittings Workmanship A pipe with flow lines, die lines, grooves and scores on its internal or external surface

Management System Sets out a framework to guide operations towards improved quality and performance.

TIP: To verify that the requirements of the applicable codes and standards are met, you can request a quality audit in the form of a

9 8 Compromise on quality process (Continued) TYPICAL PROPERTIES OF HDPE PIPE Carbon Black Dispersion Poor distribution results in stress raisers and reduces the lifespan of the pipe Carbon Black Content Relates to long-term product performance Reprocessed Polymer Lowers the expected product lifespan, and physical and mechanical properties Circumferential & Dimensional Irregularities Results in pipe failure and leaks due to uneven stress distribution in the pipe wall Dimensions Affects the pressure performance, welding strength and sealability of pipes and fittings Workmanship A pipe with flow lines, die lines, grooves and scores on its internal or external surface will not be able to withstand long-term operating pipe pressure / improper welds (premature failure) SANS ISO 9001:2008 Quality Management System Sets out a framework to guide operations towards improved quality and performance. The system is governed by a number of overarching principles and requirements that focus on delivering consistently good quality products. TIP: To verify that the requirements of the applicable codes and standards are met, you can request a quality audit in the form of a factory tour to determine whether a pipe manufacturing facility is qualified for and capable of delivering quality compliant products. If you are unsure, ask SAPPMA, IFPA or a trained Marley representative

10 9 Compromise on social & environmental responsibility Every year, water loss costs South Africa up to R7.2 billion a year as a result of leaky pipes and sub-standard infrastructure The plastic pipe manufacturing industry is characterised by modern manufacturing processes operating in a competitive and challenging environment. In addition to meeting a wide variety of exacting customer requirements, producers of pipe products must also respond to ongoing developments in the industry as a result of changing safety, health, environmental, quality and risk management issues. ENVIRONMENTAL CONSIDERATIONS Compliance with relevant environmental laws and the requirements of ISO 14001:2004 system Selecting appropriate raw materials and supplies to minimise pollution levels of waste Elimination of heavy metal additives from the workplace environment SANS Clause 5 states: When used under the conditions for which they are designed, materials in contact with, or likely to come into contact with, drinking water shall not constitute a toxic hazard, shall not support microbial growth and shall not give rise to an unpleasant taste or odour, to cloudiness or to discolouration of the water. The concentrates of substances, chemicals and biological agents leached from materials in contact with drinking water, and measurements of the relevant organoleptic/physical parameters, shall not exceed the maximum values recommended by the World Health Organisation (WHO) or as required by EC Council Directive 98/83/EC, whichever is the more stringent in each case. HEALTH & SAFETY STANDARDS Provide and maintain a healthy and safe work environment as indicated by acceptable practices and legislative requirements Identify risks in all areas and take preventative actions Regular review of the efficiency of health and safety systems, communicating information about the current situation As a member of the Southern African Plastic Pipe Manufacturers Association (SAPPMA), Marley Pipe Systems continues to play a leading role in promoting the environmental benefits of plastic pipe systems which is demonstrated throughout the entire value chain from raw materials to manufacturing and distribution through to end of service life and recycling. Marley s Commitment

10 Conclusion Advocates of Quality SAPPMA (Southern African Plastic Pipe Manufacturers Association) The main purpose of SAPPMA is to facilitate high standards of ethics, product quality and technical

11 10 Conclusion Advocates of Quality SAPPMA (Southern African Plastic Pipe Manufacturers Association) The main purpose of SAPPMA is to facilitate high standards of ethics, product quality and technical information to create absolute trust and integrity throughout the value chain of the Southern African plastic pipes industry. As a member of SAPPMA, Marley abides by a code of conduct which ensures that only top-quality pipes and fittings that meet stringent industry standards enter the market. SABS (South African Bureau of Standards) The SABS deals with the promotion and maintenance of standardisation and quality in connection with commodities and the rendering of services to promote design excellence, and offer an uncompromised value-added standardisation service. Marley abides by the set national SANS specifications and internally sets its own benchmarks to exceed these requirements, e.g. test intervals/frequencies and duration are higher than those set out in the SABS Permit Mark Certification Scheme. This allows for preventative measures and immediate rectification where necessary to ensure consistency in products/processes and continuous improvement. Why Standards Matter In the plastic pipe industry where supply continually exceeds demand, manufacturers often look for ways to cut costs, often at the expense of quality. And while industry standards have been put in place by organisations such as SAPPMA and the SABS to weed out inferior plastic piping systems, lower priced products will always be available on the market that compromise quality, safety or the environment. Companies need to consider the risk that they are taking when purchasing or specifying cheaper products. The fact is: long-term product reliability in pipe systems is critical to maintain a sustainable infrastructure. According to industry standards, high quality plastic pipe should last in excess of years. In many cases, the lifecycle cost of replacing or repairing inferior piping systems before this time will by far outweigh the original savings. Marley Pipe Systems can confidently look back on several decades of leadership in the plastic pipe reticulation market. The incorporation of and commitment towards achieving the highest levels of quality, health, safety and environmental protection without compromise are key values that help us sustain our leading position and ensure that we are constantly living out our values and philosophy of Bringing tomorrow to life. IFPA (Installation and Fabrication Plastic Pipe Association) IFPA, in association with SAPPMA, serves to expand the regulation of the plastic pipe industry in Southern Africa and attend to fabricators and installers of plastic pipe, as well as suppliers of pipe fittings and related equipment. As a member, Marley operates in accordance with IFPA s code of conduct, demonstrating our commitment to matters such as product quality, sound technical information, marketed education, the environment and ethics.

12 Contact Marley Pipe Systems Y o u r V a l u e P a r t n e r Mining & Industrial Head Office 1 Piet Pretorius Street, Rosslyn, Pretoria Tel: 0861 MARLEY (627539) Branch Offices Bloemfontein: /5 Cape Town: Durban: East London: George: Jet Park (MEGAFLEX): Klerksdorp: Namibia: Nelspruit: Polokwane: Port Elizabeth: Zimbabwe FOR TECHNICAL SALES SUPPORT: 0861 MARLEY ( ) technical@marleyps.co.za

SANS/ISO 4427 PLASTIC PIPING SYSTEMS HDPE MATERIAL & PIPE REQUIREMENTS, Issue 2

Web: www.pesclab.co.za Web: www.sappma.co.za Web: www.ifpa.co.za SANS/ISO 4427 PLASTIC PIPING SYSTEMS HDPE MATERIAL & PIPE REQUIREMENTS, Issue 2 By François Prinsloo, NDip & BTech: Polymer Technology,