Presentation on Stainless Steel

This is a comprehensive presentation on Stainless Steel. It has some additional data on tests also.
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Aluminum - Water mixture leads to Explosion

TOI dated 23rd September 2011, page 19

The use of Aluminum piping has the risk of becoming a explosive material in case of fire. To avoid these situations, Firefighting sprinkler systems are preferred to use Stainless Steel as it has the additional advantages of no corrosion blocking the sprinklers in case of bulb breakage during fires (as happens in 2 out of 5 cases).

Aluminium-water explosion led toTwin Towers collapse?

Paris: A mix of sprinkling system water and melted aluminium from aircraft hulls likely triggered the explosions that felled New York's Twin Towers on September 11, 2001, a materials expert told a technology conference on Wednesday.
    “If my theory is correct, tonnes of aluminium ran down through the towers, where the smelt came into contact with a few hundred litres of water,” explained Christian Simensen, a scientist at SINTEF, an independent technology research institute based in Norway. “From other disasters and experiments carried out by the aluminium industry, we know that reactions of this sort lead to violent explosions.”
    Given the quantities of the molten metal involved, these blasts would have been powerful enough to blow out an entire section of each building, he said in a statement. This, in turn, would lead to the top section of each tower to fall down on the sections below.
    The aluminium-water scenario would account for explosions from within the buildings just prior to their collapse that have fuelled conspiracy theories suggesting that the structures had been boobytrapped. The official report on the causes of the collapse blames over-heating and failure of structural steel beams in the centre of the buildings.
    Simensen presented his theory at an international materials technology conference in San Diego, California, and has detailed his calculations in an article published in the trade journal Aluminium International Today. “The aluminium industry had reported more than 250 aluminium-water explosions since 1980,” he said. In a controlled experiment carried out by Alcoa Aluminium, 20 kilos of molten aluminium was allowed to react with 20 litres of water, along with a small quantity of rust. “The explosion destroyed the entire laboratory and left a crater 30 metres in diameter,” Simensen said. By comparison, the aircraft carried 30 tonnes of aluminium into each of the towers, according to his calculations. PTI

NEW THEORY: A mix of sprinkling system water and melted aluminium from aircraft hulls likely triggered the explosions that brought down the Twin Towers on 9/11, says a scientist

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Delhi Jal Board facing Corrosion problems

Delhi Jal Board has been facing a number of complaints from the users about the Leaking pipes and mixing of sewage water in the drinking water. This is mainly due to the use of GI/ Mild Steel Pipes.

Use of Stainless Steel pipes addresses these issues in the best way.

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Lifecycle Approach to SS in Plumbing

Life-Cycle Cost Analysis

A typical life-cycle cost (LCC) calculation should take the following factors into

account:

• Material Cost • Fabrication Cost • Installation Cost

• Maintenance cost • Replacement Cost • Disruption cost

But typically, in most analysis, only the first 2 or at the most 3 factors are

considered. As a result of this, the study becomes skewed and when the other

costs are incurred during service life, the decision looks like a bad decision in

retrospect. To overcome this phenomenon, it is advisable to include all the costs.

An example of this analysis in water piping in a typical bathroom of a house is as

shown below:

LCC for 50-year life of Plumbing systems

Cost G I SS

Material cost 4,000 10,000

Installation Costs 4,000 4,000

Total 8,000 14,000

Average Life 10 years 50 years

Repairs during life Once (every 10 years) Nil

Cost of Repair (5 times) 10,000 0

Replacement 4 times (@Rs.15000/-) Nil

Cost of Replacement 60,000 0

Cost of Interiors 60,000 0

Total Lifecycle cost 138,000 14,000

(Disruption cost of GI not included)

Therefore, the actual cost of installing a Stainless Steel piping system is 1/10 of the GI system in the life of a house.

For details: please download the complete paper from http://stainlessindia.org/UploadPdf/MAY_2011.Pdf

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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

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