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GI Pipes as Sewage Carriers?

Are Galvanized Iron pipes suitable for usage as sewer carriers in a sewage pumping station ? In one of the projects, the contractor has insisted on usage of GI pipe as pumping main in preference to CI specified in BOQ. The influent sewage is mixed type in a coastal belt.

N.J.Suresh

suresh_nittoor@yahoo.com

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Comments

1.

Dear Suresh,

When a contractor insists on using galvanised iron (GI) pipes as sewer carriers in sewage pumping instead of cast iron (CI) pipes mentioned in the Bill of Quantities (BOQ), there is definitely need to study its implications.

GI pipes are iron pipes coated with zinc to prevent rusting and corrosion. They find extensive use because they are cheap, light in weight and easy to transport and handle. The problem with them is that, on ageing, the zinc coating gradually wears away to expose the iron to rust rapidly in the presence of water. They are then prone to clogging, scale formation and corrosion, necessitating replacement. The problem is further aggravated in not taking proper care to protect them against contact with concrete, cement mortar, lime mortar, plaster or wall/suspended floor during their laying. Any delay in the replacement of these leaking GI pipes leads to environmental pollution.

In contrast to this, properly laid CI pipes provide trouble free service for a long time.

Hope the information provided will be of use for you to take a decision in the matter.

Best wishes,

Dr. R. Jagadiswara Rao
Retired Professor of Geology
Sri Venkateswara University
Tirupati, AP 517502
rjagadiswara@gmail.com

Dr. R. Jagadiswara Rao, Professor of Geology Retired, Sri Venkateswara University, Tirupati, AP 517502, India rjagadiswara@gmail.com

2.

Dear N.J.Suresh,

GI pipes are not used. Generally in sewage rising main C.I./D.I/HDPE pipes are used. For more information please refer CPHEEO Manual for Sewerage and Sewage treatment. Kindly go through the link here: http://cpheeo.nic.in/

Regards,

V. K. Babbar
Chief Engineer (Civil)
Delhi Jal Board
New Delhi-110005

3.

Dear Suresh,

We opine that in your project the contractor opting for GI pipes, wouldbe for easy connectivity to already laid lines if for new project for easy connection to other link lines/ make joints Etc.

It is to be noted that the sewage is a highly corrosive liquid, having organic acids and at some odd places with moisture vapours ( water) combining with H2S producing Sulphuric acid, These vapours gets lodged into the pipeline elements, joints, welds etc..( over head welds) and cause all the damage in time to come.

It is very important to use good grade material- CI/ HDPE/ DI pipes, and back filling and compacting use good material to avoid collapse of pipes in future.
As indicated by Er.VK Babbar, refer to and consult CPHEEO manual,
of the records I would recollect Er.Uppal with his collegues taking a lot of pain-staking efforts in compiling practical principles and practices of sewage, waste-water treatment etc. All data compiled in the CPHEEO Manual has been done well, and to be put to use by practicing PHE officials.

With wellwishes from VigyanVijay,

AjitSeshadri
ajit.seshadri@vigyanvijay.org

Er. Ajit Seshadri,Head- Environment, The Vigyan Vijay Foundation

4.

Dear Mr. ASuresh,

GI Pipe for untreated sewage is not at all recommended. It will get corroded soon.

Prof. R. V. Saraf
Viraj Envirozing India Pvt. Ltd.
Pune
watersgs@vsnl.net
For more details : http://www.virajenvirozing.com

5.

Dear N.J.Suresh,

I think as a force main for conveyance of sewage, C.I. Pipe or D.I. pipe (as per specification of BIS) would be appropriate.

Regards

Dr Arunabha Majumder
Chairman
Indian Water Works Association (IWWA)

6.

Dear N.J.Suresh,

The choice of material indicated by the contractor is acceptable since, you have indicated the mix of sewage in a coastal area. Cast iron is easily susceptible to rusting in coastal environment and galvanizing is a better option. However, things have changed recently with availability of HDPE pipes (high density polyethylene pipes) which can be used under a wide variety of conditions.

With regards,

M. Karthik
Scientist C
Waste Water Technology Division (WWT)
National Environmental Engineering Research Institute
Nagpur

7.

There seems to be contradictory opinions on my question. Could some Final authority settle the discussion please.

8.

Dear N.J.Suresh,

As per norms recommended by PCB C.I. pipe is suitable for above purposes. G.I. and C.I. booth is oxidising agent creating always corrosion. To avoid this problem use only P.V.C. or PPR only.

Thanks

With regard

Sirajul Haque
Consultant
Water Resource

9.

The use of HDPE pipe is most appropriate solution for carrying any type of water.The polyethylene is chemical resistance and the bore of HDPE pipe is smooth as compared to any metal pipe ,thus the flow rate of is better.Plastics does not corrode and and having longer life span.

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