40 CFR Part 63, Table 32

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗

Tank diameter D (feet) b	Pontoon roof	No. of legs on double-deck roof
No. of pontoon legs	No. of center legs
30	4	2 \| 6
40	4	4 \| 7
50	6	6 \| 8
60	9	7 \| 10
70	13	9 \| 13
80	15	10 \| 16
90	16	12 \| 20
100	17	16 \| 25
110	18	20 \| 29
120	19	24 \| 34
130	20	28 \| 40
140	21	33 \| 46
150	23	38 \| 52
160	26	42 \| 58
170	27	49 \| 66
180	28	56 \| 74
190	29	62 \| 82
200	30	69 \| 90
210	31	77 \| 98
220	32	83 \| 107
230	33	92 \| 115
240	34	101 \| 127
250	34	109 \| 138
260	36	118 \| 149
270	36	128 \| 162
280	37	138 \| 173
290	38	148 \| 186
300	38	156 \| 200
310	39	168 \| 213
320	39	179 \| 226
330	40	190 \| 240
340	41	202 \| 255
350	42	213 \| 270
360	44	226 \| 285
370	45	238 \| 300
380	46	252 \| 315
390	47	266 \| 330
400	48	281 \| 345

a This table should not supersede information based on actual tank data.

b If the actual diameter is between the diameters listed, the closest diameter listed should be used. If the actual diameter is midway between the diameters listed, the next larger diameter should be used.