Hollow vessels

  • Hollow vessels may require temporary stays during the galvanizing process to prevent distortion 
  • Hollow vessels should have at least 1 vent hole and 1 drain hole 
  • Standard minimum venting and draining for an enclosed volume is a 50mm diameter hole for each 0.5m3 (see Table 4) 
  • Openings should finish flush inside the vessel 
  • Baffles inside vessels should have openings to allow free flow of liquid throughout. A minimum of 75mm snipes is required. See Figures 8 to 11 for more information on snipes.
Table 4: Minimum hole sizes for hollow vessels

Section Volume (litres)

1 Hole
Ø (mm)

2 Holes
Ø (mm)

4 Holes
Ø (mm)

500

50

35

25

1000

70

50

35

1500

90

65

45

2000

100

70

50

2500

115

80

55

3000

125

90

65

3500

135

95

70

4000

145

100

70

4500

150

110

75

5000

160

115

80

5500

165

120

85

6000

175

125

90

6500

180

130

90

7000

190

135

95

7500

195

140

100

8000

200

145

100

8500

210

145

105

9000

215

150

110

9500

220

155

110

10000

225

160

115

Figure 28 – Hollow Vessels – Good Design

Figure 29 – Hollow Vessels – Bad Design