PB (polybutylene)
pipe and tubing

PB plumbing was made in two forms: pipe (SDR 11) and tubing. The pipe sizing systems were the old IPS (Iron Pipe Sizes) also employed for PVC; the tubing sizes were (all dimensions in inches):

PB 21 SDR 11 Tubing
Nominal
Size
Average
Outside
Diameter
Minimum
Wall
Thickness
1/8 0.250 0.040*
3/16 0.312 0.062*
¼ 0.375 0.062*
3/8 0.500 0.062*
½ 0.625 0.062*
¾ 0.875 0.080
1 1.125 0.102
1.375 0.125
1.625 0.148
2 2.125 0.193

* Not determined by the SDR.

History

PB pipes began to be installed in U.S. homes in the late 1970's, continuing through the middle of the 1990's. PB is much less expensive than copper and, more significant, the labor cost of installing PB, which is flexible, was lower than that for rigid PVC.

Do-it-yourself writers touted the ease of installation of PB plumbing: “Because it is often contorted, polybutylene is considered unsightly, so it is usually used behind walls or between floors and ceilings. It is excellent for remodeling jobs because it can be threaded through difficult spots where demolition would be required if rigid pipe were to be used instead. … Flexible pipe is joined more easily [than gluing rigid pipe], by threaded compression fittings.”¹ In fact, however, properly crimping the rings that held the pipe to a fitting requires a special tool, which itself requires regular recalibration. Too much or too little tightness and the connection will leak.

Within a few years, reports of leaks began to accumulate. Most of the leaks were due to failed connections, crimped to metal or acetal plastic fittings. In some cases, however, the tubing or pipe itself split. One speculation was that the deterioration of the PB and the acetal fittings was caused by chlorine-containing compounds in the water, the result of municipal water treatment processes. It is worth noting that PB tubing has performed well in buried geothermal (heat pump) installations.

A class action lawsuit ensued, which ended in a settlement² by which the Shell Chemical Company and Hoechst Celanese (makers of PB resin) provided $950 million to pay a portion of the cost of repiping affected homes. (The maker of the pipes and fittings went bankrupt.) This fund has been exhausted, and persons buying or owning homes with PB plumbing are now on their own.

Some cities amended their building code to forbid or restrict the use of PB.3 In some jurisdictions it is illegal to sell a home with PB plumbing without disclosing that fact.

The ASTM has withdrawn the standards4 relating to residential PB pipe and tubing, but as of 2011, the most relevant standard (D 3309) is again being scrutinized by a working committee.

 

1. John Warde. Home Improvement. New York Times, 28 July 1988.

2. Company News; Settlement Approved over Leaky Plumbing. New York Times, 10 November 1995.

3. For example, the city of Katy, Texas: "Polybutylene pipe and tubing (PB) and polyethylene pipe and tubing (PE), cross-linked polyethylene piping and tubing (PEX) shall not be used in any concealed space for purposes of this code as amended. Attics are considered a concealed space."
Or, El Paso, Texas (September 2010), amending its adoption of the International Plumbing Code (2009):
18.20.080 Table 605.3 Water Service Pipe, amended.
International Plumbing Code, 2009 Edition, Table 605.3, Water Service Pipe, is hereby amended to delete all references to asbestos-cement pipe and polybutylene (PB) plastic pipe and tubing.
18.20.090 Table 605.4 Water Distribution Pipe, amended. International Plumbing Code, 2009 Edition, Table 605.4, Water Distribution Pipe, is hereby amended to delete all references to polybutylene (PB) plastic pipe and tubing."

4. ASTM D2662-96a Standard Specification for Polybutylene (PB) Plastic Pipe (SIDR-PR) Based on Controlled Inside Diameter (Withdrawn 2003.)
ASTM D2666-96a Standard Specification for Polybutylene (PB) Plastic Tubing.
(Withdrawn 2005.)
ASTM D3000-95ae1 Standard Specification for Polybutylene (PB) Plastic Pipe (SDR-PR) Based on Outside Diameter. (Withdrawn 2003.)
ASTM D 3309-96a(2002) Specification for Polybutylene (PB) Plastic Hot- and Cold-Water Distribution Systems. (Withdrawn 2010.)

Resources

Information about the lawsuit and settlement:

www.polybutylenelawsuit.com/

This commercial site sells repiping services, but it is fair-minded and informative.

www.polybutylene.com/

The United States was not alone in developing standards for polybutylene. The German standard, reflecting that of the ISO:

DIN EN ISO 15876 "Kunststoff-Rohrleitungssysteme für die Warm- und Kaltwasserinstallation – Polybuten (PB)" in den Teilen 1, 2, 3 und 5.

DIN ISO/TS 15876-7 "Kunststoff-Rohrleitungssysteme für die Warm- und Kaltwasserinstallation – Polybuten (PB) – Teil 7: Empfehlungen für die Beurteilung der Konformität".

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