11 replies to this topic

[SenOil]

Hi all

Looking for how to design a pipe manifold for natural gas.

I have the following datas:

The inlet (into the manifold) are 2No.2"pipes and 2No.3"pipes
The outlet (from the manifold) are 1No. 4" pipe dedicated for production line and 1No.2" pipe for testline

,Q=71000Nm3/d from flowline, flowline pressure 640 psi.What is the good size of the main pipe ie The outlet (from the manifold) and the inlet (into the manifold) ??Are there any math calculations from API or others regulations that give us the size?

Any help would be appreciated!!

I attached an excel chart for a better understanding and more informations about the system configuration.

 

many thanks

Attached Files

•  Pipe manifold design data.xlsx   12.43KB   206 downloads

[Erwin APRIANDI]

As far as I experienced, the manifold is size with the same based as the flowline.

No other specific rules, unless it is specified by the project.

 

Waiting for other to replied...

[SenOil]

Thank you very much Erwin for your reply i hope that the others will reply and give more advices about this.

[SenOil]

Can anybody of this forum help me to get done of this matter.

many thanks

[shan]

Production header diameter is 6" (area equal or larger than sum of all flowline areas) and test header diameter is 3" (area equal or larger the largest flowline area).

[Art Montemayor]

I agree with Shan's reply.   If you expect to converge all your wells' production into one header, you have to design for the case where all maximum capacities are being mixed into one header and that header is carrying the sum of all maximum streams.  You design the size of each piping run according to the available pressure drops and the maximum flow rates.

 

The way the headers are shown, they are definitely the wrong size - unless there is a special scope of work that allows this reduced sizing.

[ankur2061]

Senoil,

 

Why does your production header sizing be different from any other line sizing exercise? You know the flow rate through the production header, you know the pressure at the start of the production header and you know where it terminates. So all you have to do is size your production header considering an acceptable velocity limit (generally 60 to 70% of the calculated erosion velocity) and the acceptable pressure drop along the production header or in other words based on the acceptable termination pressure at the end of the production header.

 

Where is the complication in the sizing of the production header?

 

Regards,

Ankur

[SenOil]

Shan Art and Ankur2061 thank you for your reply

 

could you tell me the origin of this rule you stated {Production header diameter is 6" (area equal or larger than sum of all flowline areas) and test header diameter is 3" (area equal or larger the largest flowline area)}. its from API, ASME or any others regulations? I want to show it to my manager,

 

To Ankur2061, you say "Why does your production header sizing be different from any other line sizing exercise?" because we have only 2" and 3" pipe available in stock. I was worrying about how to size the production header which collect 4 branches flowing into the manifold by considering flow-rate and pressure loss @ each branch on the manifold,

 

are there any formula to be consider for this, honestly I don't know where to start or what to do to or formula to use to size the production header by considering acceptable pressure loss, flow-rate, velocity,

 

thanks in advance.

[Art Montemayor]

 

Senoil:

 

There is no “rule” to my logic, just common sense:

 

Assuming that the well flowlines are calculated accurately and for the maximum flow rate from each well, the header that receives all 4 lines (2-2” and 2-3”) must also have the same capacity expressed in cross-sectional area.

 

2” pipe flow area = 2.9528 in²

3” pipe flow area = 6.6051 in²

 

Header required pipe flow area = (2) (2.9528) + (2) (6.6051) = 19.11 inch²

 

Header pipe size = 6” (23.75 in²; 5” pipe size is a bastard)

 

If your flowlines are not designed correctly then you must do as Ankur has recommended: do the basic piping design to find out what is available as the appropriate sizes for your required flows.

 

[SenOil]

Thank you Art for your advice

[SenOil]

I have a problem to find out what formula to use for pressure Drop calculation for sizing the lines cause I have multiphase flow (Gas,condensate, water)

I only know Weymouth equation for single phase

 

Single phase (Gas) (≤ 12")

 

[shan]

Senoil:

 

It is not from API, but from IPA (It's Practically Accepted).