Pipe thickness Calculation using ASME B31.3

[m.wasif]

I am determining the schedule for A106 Gr B Seamless pipe for the following conditions:
Operating Pressure: 70 bar
Temperature: 120 Farenheit
NPS: 3 inch
Service: Hydrogen

How may i convert my operating pressure into design pressure???

 

[LittleInch]

You can't convert it, only decide what the design pressure needs to be based on the process conditions.

You need to know what the worst case condition is that isn't totally abnormal.

Usually the pipe schedule will have decided this.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[JohnGP]

If 70 barg is the maximum operating pressure then it would not be unreasonable to add 10% to this to use as design pressure. But you need to evaluate with due consideration of the means of pressure control of the system, and whether upset conditions can peak above the stated operating pressure.

 

[MickMc]

As a rule of thumb if the design pressure cannot be calculated by Process Engineer due to known conditions a figure of +25% of operating pressure is added as a safety factor and commonly this figure or another is stated in client specifications. If not stated anywhere client should be consulted.

 

[m.wasif]

Thanks for answers

 

[JohnBreen]

You really need to include additional wall thickness for corrosion (internal and external)over the expected life and certain dynamic wave effects e.g. water hammer and (in some cases) bubble collapse. Develop and review a list of these possible internal and external dynamic effects. Also include factor for seamless pipe, and seam welded (or spiral welded) pipe.

 

[KevinNZ]

Design pressure needs to the worst pressure case from the fluid source. This maybe limited by safety valves or heat input etc.

For transient effects that act for a short time you can reduce the design pressure by a few % from peck. See the piping code.