FREQUENTLY ASKED QUESTIONS

What is PE (as in HDPE, MDPE, LDPE, LLDPE, etc.) and what are some of its uses?

Polyethylene (PE) is a plastic material belonging to a group of polymers called polyolefins. It is usually first categorized by its density as indicated in the abbreviations e.g. HDPE (high density PE), MDPE (medium density PE), LDPE (low density PE) , LLDPE (linear low density PE). Depending on its specific grade and properties, it is used in a wide range of plastic products from milk bottles and plastic bags (lower end of properties and cost) to high performance plastic pipes (high end of properties and cost).

What is used to make PE or HDPE?

All polyethylenes are made from petroleum feedstocks also known as hydrocarbons. Both the feedstocks (and raw materials) and polyethylene is composed of only hydrogen and carbon (hydrocarbon).

What is a polymer?

A polymer by definition is poly (many) mer (parts). It is generally a very simple molecule (mer) which is chemically combined (polymerized) many times until it attains the final desired properties as a polymer.

What is a stabilizer (thermal vs. ultraviolet stabilizer)?

Stabilizers are added to polymers to enhance their ability to resist natural, environmental, mechanisms which tend to shorten their useful lives. Antioxidants retard oxidation ultraviolet stabilizers retard sunlight degradation, and thermal stabilizers help buffer the degradation effects of high temperature exposure.

What is TiO2?

TiO2, titanium dioxide is essentially an inert white pigment which whitens and opacifies plastics.

What is carbon black?

Carbon black is a black pigment, which can also enhance mechanical properties as well as act as an excellent UV stabilizer when properly compounded into a plastic or rubber.

Are PE pipe and fittings safe for use in homes? *Reference ASTM and NSF performance and health standards.

Yes, PE is safe for use in the home. As answered above it is a polymer composed of only carbon and hydrogen atoms. PE is commonly used for food containers (milk bottles, plastic food bags, etc.) when the plastic has received approval to NSF International's standards health effects applications by a third party certifying agency. Examples of such standards are NSF 14 and NSF 61.

What is ASTM?

ASTM (American Society for Testing & Materials) is an independent, not-for-profit standards writing organization. It promulgates standards in many diverse technical disciplines. ASTM is the forum for a majority of standards in the USA, especially those related to plastic materials and products testing. ASTM writes standards and conducts educational training seminars (Specifications, Test Methods and Guides. ASTM does not conduct testing, listing, certifying, or enforcement of its standards.

What is NSF?

NSF (NSF International) is an independent, private, not-for-profit, 3rd party certification, testing, and standards writing organization. NSF is accredited by ANSI, (the American National Standards Institute), RvA, (the Dutch Raad voor Accreditatie), and SCC, (the Standards Council of Canada) for its testing, standards writing, and certification programs. NSF writes consensus standards for product, material, and system assessment. NSF provides an array of testing services to many different industries. NSF provides the plumbing industry services for items such as pipes, fittings, valves, pumps, water heaters, sinks, showers, toilets, faucets, controllers, filters, materials, and ingredients. NSF does conduct testing, listing, certifying, and enforcement of its standards.

What is PPI?

PPI (a.k.a. the Plastics Pipe Institute) is a trade organization whose members include plastic manufacturing companies, plastic piping product manufacturing companies, related equipment and chemical suppliers and educators and consultants to the plastic pipe industry.

What is ASTM D 3350?

This is an ASTM Standard which provides a cell classification method for classifying plastics. When classified under D 3350 the plastic material receives an alphanumeric designation, which identifies its mechanical and chemical properties. It is a shorthand method for describing a plastic material.

What is NSF Standard 14?

ANSI/NSF Standard 14 Plastic Piping System Components and Related Materials is a consensus standard promulgated by NSF International. This standard enables comprehensive assessment of plumbing system products, materials, and ingredients for health effects, quality control, quality assurance, marking, material property requirements, long term strength evaluation via PPI TR-3, and short term product performance to various standards such as ASME, ASTM, ASSE, etc.

What is NSF Standard 61?

ANSI/NSF Standard 61 Drinking Water System Components-Health Effects is a consensus standard promulgated by NSF International. This standard enables in depth assessment of a variety of drinking water system products and materials for health effects. This standard is used to evaluate a product for health effect concerns only.

What is PPI TR3?

(Plastic Pipe Institute's Technical Report 3) PPI TR3 is a standard published by PPI which describes, in depth the testing, calculations and theory by which plastic materials are tested to determine their long term strength properties primarily for pressure piping applications. These long-term strength properties (up to 50 years or more) are published, by material, in PPI TR4, which lists this property as an HDB or hydrostatic design basis. These HDBs are then used by engineers in designing plastic piping products for excellent long term service.

What does PE 4710 mean?
PE 4710 is a new designation for improved high performance PE materials.

To understand the new PE 4710 designation and its commercialization, we must first explain the older PE 3408 designation and its use in the design of polyethylene piping. The term PE 3408 is based on the standard thermoplastics pipe material designation code defined in ASTM F 412 and it has been referenced extensively within the North American piping industry since the early 1980’s.

The standard thermoplastic pipe material “code” for polyethylene consists of an abbreviation for the type of plastic followed by 4 numbers that describe its key properties.  The last two numbers refer to the hydrostatic design stress (HDS) for that material in units of 100 psi with any decimal figures dropped.

In the chart above the term PE 3408 identifies the piping product as a polyethylene grade PE34 with a density cell class of 3, a “slow crack growth” cell class of 4 (both in accordance with ASTM D3350-04), and an 800 psi maximum hydrostatic design stress at 73°F as recommended by the Plastics Pipe Institute (PPI).

In the mid-1980’s, extensive research further improved on the recognized performance of polyethylene piping materials.  The result of this research was the introduction of a new significantly improved polyethylene resin that was designated as PE 100 in accordance with the ISO standards used outside of North America. 

In order to commercialize the high performance PE resins within the North American market, ASTM had to expand its coding system in ASTM D3350-06 to properly represent the improvements made and PPI’s Hydrostatic Stress Board (HSB) had to define the high performance criteria in utilizing a new design factor to establish the hydrostatic design stress for water at 73°F.  Based upon the actions in ASTM and the PPI-HSB, a new standard thermoplastics pipe material designation code of PE 4710 resulted.  The chart below illustrates how this pipe material designation code provides a basis for recognition and identification of the higher performance capability of these new piping products. 

1 1600 psi hydrostatic design basis (HDB) X 0.5 design factor (DF) = 800 psi hydrostatic design stress (HDS) for water at 73°F
2 1600 psi hydrostatic design basis (HDB) X 0.63 design factor (DF) = 1000 psi hydrostatic design stress (HDS) for water at 73°F