PSI - Issue 13

Hikaru Yamaguchi et al. / Procedia Structural Integrity 13 (2018) 1183–1188 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

1185

3

240

9.5

5

Hoop direction

50

Fig.1 Experimental set up and configuration of DWTT specimen, unit in mm.

2.3. Burst Test

A burst test was conducted. Table 3 shows burst test conditions. An axial surface notch was machined at the pipe center. The pipe was placed on the ground. The pipe was filled with nitrogen gas and pressurized by the gas and subsequently by water through a reservoir pipe, i.e. full gas burst test. Figure 2 shows instrumentation. Five pressure transducers were installed and the pressure was measured dynamically. Static pressure was also monitored. Strain gauges and timing wires were attached to measure dynamic strain and crack velocity in the both crack direction. Intervals of the timing wires were smaller at 700mm or more from the surface notch-tip so as to measure crack velocity more accurately near crack arrest position. Pipe wall deformation and crack opening profiles were observed by the same high-speed camera as DWTT, as shown in Fig.3. The camera was placed at 2.35m from pipe end in the pipe axial direction of the north side. Table 3 Burst test conditions Length [mm] Notch length [mm] Notch depth [mm] Gas Burst Pressure [MPa] Design factor 5,000 300 4.0 nitrogen 16.5 0.7

Fig.2 Timing wires and strain gauges for dynamic measurement of crack-tip position. Only north side is shown.

2.35

High speed camera

Test pipe

1.65

[m]

Fig.3 High-speed camera setup