cPVC Pipe failure analysis

Case Study: Piping System failures – cPVC in Premium residential society

Background

• A high rise, premium Apartment Block on Noida Expressway.

• 70,000 sqm area, Project cost of Rs 750 Crores

• The Society has 12 storey buildings, 17 towers and 4 flats/ floor. Total of about 600 flats.

• Ultramodern, 3&4 bedroom apartments and Penthouses with world class specifications

• Prime features - High-tech security, dedicated parking, Modular Kitchen with piped gas supply, Wooden Flooring, Ultra Modern Toilets, In-home Maintenance services etc. Moreover there is an in-house club with five-star offerings.

Current Status

• Flats being Handed over to the clients. Residents living in the complex for about 1 year now.

• Piping of CPVC (both external as well as in the toilets)

• External cPVC pipes running through shafts.

• Reputed cPVC manufacturer has supplied the piping system.

Issues informed to the plumbing experts

• All Flats are having problem of water seepage.

• The main pipes are getting cracked, joints leaking and the maintenance offices being flooded with complaints to rectify the problems everyday.

• The initial savings in piping material has cost the builder huge amount of money in repair and loss of reputation

Problems identified by the Project Manager

• Pipes getting deformed

– Adequate supports not provided.

• Pipes are brittle, even a small stone lying on some slab when it falls leads to pipe breakage

• The joints are leaking

– In main pipeline in all the towers

– In the toilets

– Each and every of the 600 flats have complained.

• High flow rate (no PRV)

• Joints are not durable

• When Taps/ Fittings are tightened, the pipe cracks in the toilet

• Even the repair is not reliable

• Management feeling helpless and groping in dark for solutions

Technical Analysis

• CPVC has highest thermal expansion coeff.

– For 50ºC change in temp, the 30m cPVC pipe expands by 15cm

• cPVC is brittle and at low temperature, the thin walled system is extremely brittle. They may crack even on dropping from height

• CPVC pipe and fittings are subject to cracking during earthquakes.

• Permitted flow rate is 2m/sec.

• Loud noise can be heard when water flows in some cases.

• Not all the technical issues are discussed with the Builders/ Management and decisions are made on some sales pitch

Possible Reasons for the cPVC pipe Failure

1. Thermal Expansion

• The Pipes would have been installed in Summers when the temperature was nearing 45C

• In winters (temp nearing zero C), the pipes get shrunk, leading to buildup of the stresses.

• Design to address the Expansion issue was not done.

2. Joining

• If there is too much glue applied it can actually dissolve the pipe and cause a failure.

• The jointing by solution can’t withstand these stresses and start leaking.

• Repairs may temporarily provide relief but in the summers, reverse situation will happen.

3. Inadequate Supports

• The cPVC Pipes need support at every 4’ otherwise it leads to problems

4. Brittle Material

• cPVC is a brittle material. It is not suitable for external usage in extreme weather conditions

5. Connectors

• Need to use Brass connectors for threaded fittings which is expensive

6. Future Problems

• High flow rate will soon aggravate the problem as the wear of pipe over next few years

7. Freezing Waters

• The freezing water temperature will make the pipes brittle. Need to use it carefully.

8. Ultravoilet Rays

• The cPVC pipes need to be protected from direct sunlight / UV Exposure.

9. Ageing

• As cPVC pipes age, the pipes become brittle and must be protected from physical shocks to avoid failures

10. Toxic

• When cPVC is burned (eg house fire), it emits a deadly toxic fume.

11. Installations

• Pipes if not installed properly are prone to Environment Stress Cracking

12. Damage from Rodents

• For reasons known only to rodents CPVC is highly subject to damage from rats, mice, squirrels and Opossums and may not be a good choice of materials for running under a structure with a crawl space or raised foundation, especially in rural areas

References:

· This is based on the analysis of the site and actual discussions with the management of the builder.

· The reference data is taken from various sources on the net and the websites of the cPVC pipe manufacturers.

FOR DETAILED CASE WITH PHOTOGRAPHS, PLEASE VISIT THE WEBSITE

http://cid-5dd969b2d3b67058.office.live.com/self.aspx/SS%20Plumbing/Case%20Study%20cPVC%20Failure%20analysis.docx

Read More

Stainless Steel in Architecture

Stainless Steel has immense applications in Architecture. It has applications in Roofing, Facade, panels both in interiors and exteriors, etc.

Stainless steel structures provide both strength as well as maintenance free long life. In roofing applications, it helps in reducing the airconditioning loads due to reduction in Heat transfer inside the building.

Read More

Comparison of Various Materials in Plumbing

This post compares various materials used in Plumbing.

Read More

Piping Manual for SS in Building

The Stainless Steel Piping manual can be downloaded from this link. This is a comprehensive Technical Manual and is extremely useful for all the designers and Plumbing Consultants.

http://www.nickelinstitute.org/index.cfm/ci_id/15786/la_id/1/ci_doc_id/3096/search_keyword/12008/method/2.html

Alternate Website which doesn't require any login is:

http://cid-5dd969b2d3b67058.office.live.com/self.aspx/SS%20Plumbing/12008%20-%20Piping%20Manual%20For%20Buildings-%20Japan.pdf

Read More

How stainless steel water pipes cut costs and reduce waste

Lightweight stainless steel construction permits easy and simple lifting of pipe into place, 5 metres off the floor. (Top) Two men easily connect 6-metre lengths of pipe using relatively simple equipment. In addition, there is no need to clean the ends of the grooved pipe. Stainless steel sub-assemblies and pre-fabricated and curved, mitered sections avoid the need for complex fittings and connections. (Below) Smaller diameter copper pipes deliver water to various washrooms and concession stands. Stainless steel piping has been used in Detroit's Veterans Administration Hospital since 1993. Incoming potable water is pumped through 500-mm-diameter, schedule 10 pipe, made of S30403 stainless steel. The lines are insulated to prevent condensation.

Nickel magazine, Jun. 01 -- It might take a few years, but stainless steel pipe could become as common in North American domestic water systems as it is currently in Japan or Germany. Penetration of stainless into the North American market is off to a good start with the completion of one such application at a high-profile venue in Detroit, Michigan.

The venue is a new, US$300-million stadium called Ford Field, which is being built by the Ford family, owners of the hometown "Lions" of the National Football League.

A total of 600 metres of S30403 stainless steel pipe -- 300 millimetres (mm) in diameter and with a wall thickness of 4.57 mm -- has been suspended from the concrete ceiling around the entire stadium perimeter. The grooved ends of the pipe were connected using mechanical couplings and smaller-diameter copper pipes deliver potable water from the main stainless pipe to various washrooms and concession stands around the stadium.

The pipe was manufactured by Felker Brothers and distributed by Bertsch, a USFlow Company.

W. J. O'Neil Company (WJO), a mechanical contractor, won a US$25-million contract to fabricate and install all the plumbing, waste and heating systems for the stadium, which is scheduled to open in time for the 2002 football season.

The decision to use stainless was based almost entirely on economics, according to Robert Gazda, General Manager of WJO. Although material costs were some 20% higher than if galvanized carbon steel pipe had been used, significant savings in fabrication and installation were realized as a result of opting for stainless.

The excellent corrosion resistance of stainless steel allowed thinner wall thicknesses to be used than other competitive materials, resulting in several factors that helped to reduce installation costs. Considerable weight savings per metre of pipe were realized, as well a greater ease in the handling, lifting and installation of long sections of pipe. WJO was able to install sections up to six metres long.

For the operators of the sports facility, the main advantage of stainless steel is that the lines need to be flushed only occasionally, whereas, if galvanized pipe had been used, more frequent flushing would have been required to remove the zinc corrosion products (zinc carbonate and sulphate) that inevitably develop. This means less labour will be required for flushing and less water will be wasted, an important consideration in a city where water supply costs have gone up by 30% in the past year.

Since stainless has never been used in a domestic water system in Michigan, no state engineering standard existed prior to this installation. It is not surprising, then that the City of Detroit put up some resistance. However, recent NiDI Water Workshop presentations in the region in the fall of 2000, and experience gained from the use of stainless steel cold water piping at the Veterans Hospital in Detroit, where 500-mm-diameter stainless steel pipe was installed in 1993 under Federal standards, helped convince city officials to accept the use of stainless steel at Ford Field.

Reflecting on WJO's success in developing an economical way to fabricate and install the stainless pipe, Gazda says, "I'm sure there will be a whole lot more jobs after this one."

Read More

5 years test result of SS vs other pipes

Stainless steel and other pipes used in city water supply were subjected to five year underground installation tests in 25 cities of Japan. These 5 year test results in Japan have proved that

• stainless steel piping (SS 304 or 316) have not undergone any corrosion
• the carbon steel (avg - 0.019 mm/yr) and lead pipes (0.002mm/yr) have very high corrosion rates with a maximum corrosion rate of 5-6 times these average rates.
• The cast Copper pipes and fittings have undergone frequent corrosion.

Generally speaking, SS 304 pipes didn't develop any degradation at site except slight discoloration and exhibited excellent corrosion resistance. SS 316 pipes were free from even the discoloration.

Read More

Water Pipe Material in Hospitals - NHS Scotland

An interesting extract

"Scottish Health Technical Memorandum 04-01:"

The control of Legionella, hygiene, ‘safe’ hot water, cold water and drinking water systems

11.8 The materials generally used for the conveyance of water in healthcare premises are stainless steel or plastics. Copper is only used in exceptional circumstances such as, an extension to existing premises with short life expectancy, or very small stand alone premises. Where this is specified, only lead-free solders should be used.

11.9 Substances leached from materials of construction of pipes, cisterns or other water fittings in contact with water must not adversely affect the quality of water stored or drawn for domestic or food production purposes (Water Byelaws (Scotland) 2000).

11.10 Direct gas-fired water heaters are particularly prone to corrosion and scale formation, and the inside of these heaters should be provided with suitable linings to limit these effects. Steel pipes and fittings

11.12 The character of water in Scotland is such that steel, whether galvanised or not, should not be used at all for domestic hot and cold water installations. Any existing premises with such pipework shall have this scheduled for early replacement.

Stainless steel

11.13 Stainless steel is being increasingly used in hot and cold water service systems. Reference should be made to SHTN 2: ‘Domestic hot and cold water systems for Scottish health care premises’.

Copper pipes and copper/copper alloy fittings

11.14 As described previously, careful consideration will be required if copper pipework and fittings are to be specified for healthcare premises in Scotland. Where this is considered to be acceptable either due to the size of the project or the anticipated lifespan of the facility, the following will apply.

11.15 Copper in general is resistant to corrosion. Unless resistant to dezincification, brass fittings must not be used where water conveyed is capable of dissolving undue amounts of zinc from the fitting. External protection from corrosion for buried pipework may be obtained by using copper tube with a factory-applied polythene sheath.

http://www.hfs.scot.nhs.uk/publications/1265986939-v24%2520SHTM%252004-01%2520Part%2520A.pdf

Read More