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8 comments
Anonymous Poster

Piping Standards for Calculating Minimum Wall Thickness

12/28/2009 6:57 PM

I need to calulate the minimum wall thickness for carbon steel pipe that wil be used for potable water transmission line , the operating temperature chosen will not exceed 200 F.

For potable water pipeline application , can I use the Power Piping code ASME B31.1

tm = P Do / (2 S + 2y P) + C (ASME Code B31.1) , Inaddition ,considering the manufacturer wall thickness tolerance , ts X 0.875 = tm .

or do I have to go for another piping code to calculate the minimum wall thickness ?

Material : ASTM ASTM A53 Grade B, ERW , SCH-40

PLain end pipes - welded joints - Potable water rtransmission line

Nominal Pipes Size : 16" inch

Regarding the corrosion allowance (C) - additional thickness - the application will be for potable water transmission line - carbon steel pipe -,and internally cement lined according to AWWA C205 , the life time is 20 years . I will consider it 1/16" or it should be less as the pipeline is internally cement lined ??

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Anonymous Poster
#1

Re: Applicable code to calculate mnimum wall thickness

12/28/2009 7:02 PM

Referring to the above question , the working pressure is 40 bar , and it was a mistake to put schedule 40 , as I need to check if the pipe of SCH40 wall thickness can withstand the 40 bar working pressure.

Thanks,

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Guru
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#2

Re: Applicable code to calculate mnimum wall thickness

12/29/2009 8:37 AM

The schedule of pipe required can be read from piping codes. The temperature and the pressure are the only criteria required to select suitable pipe and flanges. Recalculation of these criteria, like re-designing the proverbial wheel, is not required.

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Active Contributor

Join Date: Aug 2007
Posts: 11
#3

Re: Applicable code to calculate mnimum wall thickness

12/29/2009 9:44 AM

I noticed from your questions that you need first :to know if your line is piping or pipeline ; as if its piping you will use B31.1 or B31.3

(for help check out http://cr4.globalspec.com/thread/20161/ASME)

then if its pipeline you will use B31.4 (please check the B31.4 scope out)

second you need to know the design pressure of the line to get the correct thickness as it will based on the design pressure not the working one.

, and also you need to determine the design temperature as the code using will be limited to it.

after that I will be able to let you know how to calculate the minimum pipe wall thickness .

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Posts: 11
#4
In reply to #3

Re: Applicable code to calculate mnimum wall thickness

12/29/2009 10:07 AM

also know

Piping = compound noun for pipe work in general which includes a plurality of pipes, joints, valves, unions and other related equipment.


Pipeline = generally long sections or lengths of piping of larger diameters that run cross country carrying oil, natural gas or even water

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Anonymous Poster
#5
In reply to #3

Re: Applicable code to calculate mnimum wall thickness

12/29/2009 10:18 AM

Dear Mbaz 81 ,

The steel pipes will be used for Potable water pipelines .

I suggested to use ASME B31.1 code , because I found many companies that fabricate carbon steel pipes , they refer to this code when they calculate the working pressure , such as Wheatland Tube Company/USA.

The design pressure : 50 bar

The design temperature : 200 F

Thanks,

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Anonymous Poster
#6
In reply to #5

Re: Applicable code to calculate mnimum wall thickness

12/29/2009 1:23 PM

I did a calulation to know the minimum wall thickness required for carbon steel pipe (ASTM A53 Gr.B , type E) that will be used for potable water pipes.

I did the calculation according to two ASME codes :

ASME B31.1 : Power Piping
ASME B31.4 : Pipe line transportation system

The calculated minimum wall thickness according to the first code (ASME B31.1) was much greater than the MWT calculated according to the second code , is that because the power piping code assumes that number of joints , valves ,and fittings existing much more than that at the pipeline ? Inaddition , the allowable stress value (S=25,200 psi ) at the first code was higher than the maximum allowable stress at the second code (S=12800 also) , Moreover , the weld joint efficiency factor at the first code is 1 , while at the second code 0.85 ? why we have this difference if we are dealing with the same material ? in both calculation I neglected the corrosion allowance factor and I consider it ZERO ?

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Guru
Engineering Fields - Piping Design Engineering - New Member Egypt - Member - Member since 02/18/2007

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#7

Re: Piping Standards for Calculating Minimum Wall Thickness

12/29/2009 11:11 PM

• You can use piping code ASME B31.3 (Process Piping) or B31.4 (Liquid Pipelines), and follow the solved example to find the pipe wall thickness as indicated in the following CR4 Threads: Pipe minimum allowable thickness, In service pipe thickness limits & Schedule of pipe.

• Also, it is very important in the early stage of design to take into consideration the Pipe Wall Mill Tolerance as indicated in the following CR4 Threads: Maximum Wall Thickness for Seamless Pipe & Significance of "-Mill Tolerance" in the Piping Stress Analysis

• Or you can apply the tolerance as per API 5L as indicated at CR4 Thread: Pipe Wall Thickness.

Notes

1. For cement lined pipes, we can consider zero corrosion allowance, or the worst case use 1/8".

2. The piping material ASTM ASTM A53 Grade B, ERW can be used but may be you need higher schedule than Sch.40, and that depends on NPS and MAWP.

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#8

Re: Piping Standards for Calculating Minimum Wall Thickness

12/30/2009 1:40 AM

Please refer to ANSI/AWWA C200 - Standard for Steel Water Pipe - 6inch and Larger and AWWA Manual M11 - Steel Water Pipe - A Guide for Design and Installation. These two standard would give you the complete answer.

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Abdel Halim Galala (1); AbdulWasay (1); Anonymous Poster (3); mbaz_81 (2); PWSlack (1)

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