pipeline-integrity 1.1

Pipeline integrity calculation

PipelineIntegrity library

In Russian

Free, open source PipelineIntegrity library designed to calculate the degree of danger of pipeline metal loss defects according to the ASME B31G method.

Installation

pip install pipeline-integrity

Usage

A pipe under pressure, with a length, diameter and wall thickness from specified material.

from pipeline_integrity.material import Material
from pipeline_integrity.pipe import Pipe

pipe = Pipe(
  440,  # length, inches
  56,  # diameter, inches
  0.63,  # wall thickness, inches
  Material(  # pipe material
    "Steel",
    52000  # SMYS, psi
  ),
  900  # pressure, psi
)
)

Metal loss defect with a specified position on the pipe and a specified depth.

defect = pipe.add_metal_loss(
  40,  # the defect starts at a distance of 40 inches from the beginning of the pipe
  4,  # defect length 4 inches
  10,  # along the circumference of the pipe, the defect begins
       # at 10 arc minutes from the top of the pipe
  20,  # the size of the defect along the circumference is 20 arc minutes
  0.039  # defect depth 0.039 inches
)

Context for calculating the degree of severity of the defect according to the ASME B31G method

from pipeline_integrity.method.asme_b31g import Context

asme = Context(defect)

Defect depth less than 10% wall thickness, no danger.

from pipeline_integrity.method.asme_b31g import State

assert defect.depth == 0.039
assert pipe.wallthickness == 0.63
assert asme.pipe_state() == State.Ok

The depth of the defect is more than 80% of the pipe wall thickness, repair or replacement of the pipe is necessary.

defect.depth = 0.6
assert asme.pipe_state() == State.Replace

The depth of the defect is 50% of the pipe wall thickness, but the length of the defect does not exceed its maximum allowable length. The defect is not dangerous.

defect.depth = 0.31
assert defect.length == 4
assert round(asme.defect_max_length()) == 5
assert asme.pipe_state() == State.Safe

A defect with a length of 20 inches and a depth of 50% of the pipe wall thickness requires repair at the specified working pressure in the pipe.

defect.length = 20
assert asme.pipe_state() == State.Repair

When the operating pressure is reduced to a safe value, the defect does not require repair.

assert pipe.maop == 900
assert round(asme.safe_pressure, 2) == 700.68
pipe.maop = 700
assert asme.pipe_state(is_explain=True) == State.Defected

If you call pipe_state method with parameter is_explain=True, then you can get explanation in text form.

asme.explain()

The relative defect depth == defect depth / pipe wall thickness * 100%.
0.31 / 0.63 * 100 = 49.206
Calculation of the maximum allowable defect length.
Parameter B.
The relative defect depth 49.206 more than 17.5%.
B = sqrt(pow(0.492 / (1.1 * 0.492 - 0.15), 2) - 1) = 0.763
L = 1.12 * B * sqrt(diameter * wallthickness)L = 1.12 * 0.763 * sqrt(56 * 0.63) = 5.073
The length of the defect 20 exceed the maximum allowable length 5.073.
It is necessary to calculate the allowable pressure for defect.
Calculation of the maximum allowable pressure.
Parameter A for defect length 20.
A = 0.823 * defect_length / sqrt(diameter * wallthickness)
A = 0.823 * 20 / sqrt(56 * 0.63) = 2.771
Design pressure.
Design_press = 2 * material_smys * wallthickness * design_factor * temperature_factor / diam.
Design_press = 2 * 52000 * 0.63 * 0.72 * 1 / 56 = 842.4.
Parameter A less than 4.
a_pow = sqrt(pow(a_param, 2) + 1).
a_pow = sqrt(pow(2.771, 2) + 1) = 2.946.
Safe_press = 1.1 * design_press * ((1 - 2/3 * rel_depth) / (1 - 2/3 * rel_depth / a_pow)).
Safe_press = 1.1 * 842.4 * ((1 - 2/3 * 0.492) / (1 - 2/3 * 0.492 / 2.946)) = 700.683.
Use safe pressure 700.683 as maximum allowable pressure.
The working pressure 700 does not exceed the allowable pressure 700.683.
The defect is not dangerous.

Development

$ git clone [e-mail]:vb64/pipeline.integrity.git
$ cd pipeline.integrity

With Python 3:

$ make setup PYTHON_BIN=/path/to/python3
$ make tests

With Python 2:

$ make setup2 PYTHON_BIN=/path/to/python2
$ make tests2