Equation for calculating collapse pressure of the subsea pipeline?

Asked by mobassey 4 years, 8 months ago | 3 Answers

Can anyone please help with equation for calculating the collapse of the subsea pipeline due to external pressure?


3 Answers

0
phamus 4 years, 8 months ago

A buckle resulting from excessive bending or another cause may propagate (“travel” along the pipeline). Offshore hydrocarbon pipelines can fail by a propagating buckle caused by the hydrostatic pressure of the surrounding seawater on a pipeline with a diameter-to-wall-thickness ratio that is too high.

The minimum wall thickness, which will prevent the formation of propagating buckles, can be calculated as follows:

Note: Buckle arrestors should be used if the minimum wall thickness does not satisfy above conditions.


0
phamus 4 years, 8 months ago

The pipeline can also see buckling due to combined bending and external pressure. Combined bending strain and external pressure load should satisfy in accordance with API-1111 as follows:

To avoid buckling, bending strains should be limited as follows:

Where:

Note: A typical conservative value of 2.0 often used for safety factors f1


0
phamus 4 years, 8 months ago

The collapse pressure of the pipe must exceed the net external pressure everywhere along the pipeline in accordance with API-1111 as follows:

Where:

Pi = Internal Pressure

Po= External hydrostatic pressure

Pe = elastic collapse pressure of the pipe, in psi

Py = yield pressure at collapse, in psi

f0= Collapse factor (A 0.70 Collapse factor is required for seamless or ERW pipe)

E = modulus of elasticity, in psi

v = Poisson’s ratio (0.3 for steel)

t = Pipe thickness

D = Pipe outside diameter

Related Posts


Subsea Controls Umbilical Distribution Configuration
Subsea Controls Umbilical Distribution Configuration

PURPOSEAs part of any Pre-FEED or FEED studies, the configuration of the subsea distribution equipment should be defined in the …

Flowline - Pipeline Thermal Expansion Calculation
Flowline - Pipeline Thermal Expansion Calculation

SUMMARYFlowline/Pipeline Thermal/Pressure Expansion can be developed for submarine pipelines (both single pipe and Pipe-in-pipe) expansion assessments due to pressure and …

Application of Thermal Sprayed Aluminum to Subsea Structures
Application of Thermal Sprayed Aluminum to Subsea Structures

1.0 ScopeThis specification defines the minimum requirements for the surface preparation, application and inspection of thermal sprayed aluminum (TSA) coatings …

Pipeline Abandonment
Pipeline Abandonment

Requirements Pipelines should be decommissioned and abandoned (by removal or abandonment-in-place) in accordance with applicable national, regional and local regulations …

Subsea Commissioning Philosophy
Subsea Commissioning Philosophy

This document is to detail pre-commissioning, commissioning, start-up and performance testing requirements for the subsea system.Drilling and Completion activities related …

Subsea DeCommissioning Philosophy
Subsea DeCommissioning Philosophy

This document is to detail the requirements for decommissioning of the subsea systems, flowlines and wells.Wells, subsea and flowline systems …