7 replies to this topic

[SSU_PE]

Dear All,

Hope you are doing well!

 

This is Subodh Ubhare, working as a Process Engineer in Saudi Arabia.

 

In one of our project, we have scope of desalinated water transportation through CS pipelines.

For this design, we are referring to ANSI/AWWA C205-95. In construction, we are adhering to AWWA C205-95 for cement lining application to metallic pipeline.

 

However, while one of the paragraph of this standard specifies maximum velocities through cement lined pipeline should be less than 20 ft/s (6.1 m/s) for cement lining best performance.

 

Could I able to understand on what basis this limitation has been established by AWWA standard committee.

 

I will be grateful to see technical clarifications in this regard.

 

Regards,

Subodh.

Edited by SSU_PE, 07 January 2022 - 03:41 AM.

[PingPong]

I suspect that 20 ft/s limit is to avoid erosion, especially in bends.

 

In any case a water flow velocity of 20 ft/s would result in very high pressure drop, so hardly anybody would use that anyway, except maybe for very short pipes.

[SSU_PE]

I suspect that 20 ft/s limit is to avoid erosion, especially in bends.

 

In any case a water flow velocity of 20 ft/s would result in very high pressure drop, so hardly anybody would use that anyway, except maybe for very short pipes.

Hi PingPong,

 

You are correct, the set velocity limitation is to avoid erosion and cement lining damage.

 

But, I want to understand on what basis AWWA set it 20 ft/s, why not other value (say 25 ft/s), do they have performed any experiment to confirm this or is it based on practical/ actual field experience?

 

We are considering worst case operating scenario at this velocity and need to ensure for how much duration we can run in this state.

 

Thanks, 

Subodh.

[Bobby Strain]

To get the answer you will have to ask AWWA participants. The committee often has no particular reason; just a group consensus.

 

Bobby

[SSU_PE]

To get the answer you will have to ask AWWA participants. The committee often has no particular reason; just a group consensus.

 

Bobby

Thank you, Bobby.

 

I believe that there may be certain test/field observation as a basis, similar to Fire Relief Requirement (API 521, Appendix A).

 

So, I have started communicating with AWWA in this regard, however, I am little bit doubtful to receive the response based on experience shared by others.

 

At the same time, I am looking if anyone has confronted the same difficulty and had come out with some solution over it.

 

Thank, Subodh.

[SSU_PE]

Dear all,

 

Quick update on the above query!

 

I have received some response from AWWA technical committee.

It looks that AWWA has decided the water velocity limitation as 20 ft/s (6.1 m/s) based on other standard guideline (i.e. USBR Paint Manual, 3rd Ed.)

 

However, any comments are welcomed, to discuss further, if anyone in community has come across/experienced the pipeline water velocity as has as 6 m/s. 

 

Thanks,

Subodh.

[Pilesar]

If you are following the standard, then you follow the standard as written. What is your goal? Do you want to change the standard or do you want to justify not following the standard? Designing for 'cement lining best performance' may not be the optimum practice in specific situations.

[horatorres]

The standard 6,1 mt/seg is to prevent erosion on the lining.. 

 

You shall decide if this height velocity  is economical from the energy waste.

 

Horacio