Calculation of the pipe wall thickness for strength

initial data Liquid Water Estimatedwall temperature +5оС material: AISI 304 Subsea pipeline An increase to the wall thickness Operating gain pipe outer diameter of 133 mm or more C21 =3 mm. The estimated thickness of the pipe wall tc = p0Da/(2σφ) +c1+c2= 0,913·133/(2·173.73·1)+0.45=0,8 mm where
p0 – design pressure in the conduit, MPa,
p0 = (pi – pg min) + Δ p=1,0-0,087=0,913 MPa,
pi =1,0 MPa – the internal operating pressure of the pipeline;
pg min – minimum external hydrostatic pressure in the pipeline, MPa;
Δ p – additional pressure is calculated taking into account the pressure medium breakaway transported in the pipeline and / or water hammer pressure in the pipe, MPa.
pg min= ρw · g · (dmin – hw / 2) · 10–6=999,99 · 9,81 · 8.9 · 10–6=3,27 м=0,087 MPa;
where ρw =999.99 kg/m3, density of the water;
g =9,81 m/c2 – acceleration of gravity;
dmin =8.9 m - the minimum level of quiet water along the pipeline route, taking into account the tidal conditions and surges with the provision 10–2 1/year;
hw =0 m, the estimated wave height on the projected area of the pipeline;
Da =133 mm - outer diameter of pipe.
Allowable stress σ must be made equal to the lower of:
σ = min (Ry/ny , RT/nT),
where Ry=205 MPa - the minimum value of the yield strength of the metal pipe;
RT=510 MPa the minimum value of the tensile strength of the metal pipe;
ny=1,18 - safety factor of yield strength;
nT=1,75 safety factor for tensile strength.
σ = min(205/1,18 , 510/1,75)
σ = min(173,73 , 291,43);
φ – safety factor, determined according to the method of manufacturing a pipe, a safety factor of φ is taken equal to 1.0 for seamless pipes.
c1 =0 mm, – corrosion allowance for subsea pipelines made of stainless steels and alloys;
c2 =0,45 mm – gain compensating manufacturing tolerances for manufacturing pipes, mm.
Calculated taking into account the thickness of the wall of increases tc + C21 =0,8+3=3,8 mm
The wall thickness of the pipe diameter 133 mm accepted 4 mm.


1.РД 10-249-98 "Нормы расчета на прочность стационарных котлов и трубопроводов пара и горячей воды"
2.Правила классификации и постройки морских подводных трубопроводов Российского морского регистра судоходства от 28.02.12.

Chief technical designеr Priymak Victor


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