Calculation of Burst Yield and Collapse Yield for Round ... - Tenaris

Calculation of Burst Yield and Collapse Yield for Round Tubing
Collapse Yield We assume no internal pressure. Denote the external pressure as p 0. The axial stress is the
same as that given by (1). The radial pressure at the inner surface is zero.
Burst and Collapse Curve
To make the whole curve
look better, we take the
physically insignificant root
from the burst result
(equation 5) to add a third
curve to figure 1.
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From analytical calculations, we get hoop stress
Burst & Collapse Graph
BURST YIELD (psi)
COLLAPSE YIELD (psi)
15000
10000
5000
0
-5000
-10000
-15000
0 5000
Figure 1. Burst yield and collapse yield curve.
σ h = -2p o
Substituting (1), (7) and (8) into (4), we get
p o =
where C = 2 OD 2/(OD2- ID2). The negative sign is physically insignificant. The positive root is
the collapse yield solution. Because conventionally collapse pressure is negative, we add a
negative sign before the positive root. So,
p o collapse =
-σ a
σ r = 0
-σ a
the collapse curve based on (10) is shown in Figure 1.
Burst Yield
OD 2
OD 2 -ID 2
+ 4S 2
y - 3σa2 (9)
2C
+
4S y 2 - 3σ a2
2C
Physically insignificant burst
10000
Collapse Yield
15000
20000
LOAD (lbs)
(7)
(8)
(10)