Gas transmission pipeline

[ibrahim]

Is there any one having experience in pipeline mechanical design, as per ASME B31.8. I require guidelines about pipe thickness, insulation requirement, valve type, pipe and valve material. This will be used for natural gas transmission to about 800 kms at 500 to 200 psig pressures.

[mechcolor]

Its a complete project.
All the guidelines have been principally listed in ASME B31.8 which you have mentioned. For thickness calculation, you may go through para 841.11 and similarly material requirements are also listed in Sec. I.
If you require any specific guideline on any of the design thickness formulas (listed in code) and material requirements, you may write to me.

[ibrahim]

mechcolor, that would be a great help, if you can write me down the formula used for thickness evaluation. Service is Natural gas; H2S free. Process conditions suggest 16" line. Can you also provide guidelines for material selection.

[mechcolor]

Thickness of the pipe can be calculated by using this formula:
t = (P*D)/(2*S*F*E*T)

where,
t = required thickness, in
P = Design Pressure, psig
S = Specified minimum yield strength, psig (select the material first then look for it in Appendix D of ASME B31.8)
D = Nominal outside pipe dia, in (in your case it is 16")
F = Design Factor (look in table 841.114A of ASME B31.8)
E = Longitudinal joint factor (see in 841.115A)
T = Temperature derating factor (see in 841.116A)

For material, I suppose you would be going for a new pipe so you may select among the listed one as per ASME B31.8:
API 5L Line Pipe
ASTM A 53 Welded and Seamless Pipe
ASTM A 106 Seamless Pipe
ASTM A 134 Electric-Fusion (Arc)-Welded Pipe
ASTM A 135 Electric-Resistance-Welded Pipe
ASTM A 139 Electric-Fusion (Arc)-Welded Pipe
ASTM A 333 Seamless and Welded Pipe for Low-
Temperature Service
ASTM A 381 Metal-Arc-Welded Pipe
ASTM A 671 Electric-Fusion-Welded Pipe
ASTM A 672 Electric-Fusion-Welded Pipe

What's the design temperature and design pressure? I can then suggest you the proper material and nominal thickness (schedule of pipe) to be used.

[Nabeel Ahmed Qureshi]

Seamless pipes are more reliable than welded pipes for such services due to improved reliability of seamless pipes. This is just for information so that during design phase you might consider this.

Regards

[ibrahim]

thanks mechcolor for such an elaborative response. any idea about the pig launcher and receiving stations for oil separation piging.

[mechcolor]

Can you please elaborate what exactly you want to know about pig launcher and receiving station?