无缝钢管壁厚用STD是一种壁厚表示法
STD是标准壁厚STANDARD，按ASMEB36.10M，对应壁厚如下
直径X壁厚
10.3x1.73
13.7x2.24
17.1x2.31
21.3x2.77
26.7x2.87
33.4x3.38
42.2x3.56
48.3x3.68
60.3x3.91
73.0x5.16
88.9x5.49
101.6x5.74
114.3x6.02
141.3x6.55
168.3x7.11
219.1x8.18
273.0x11.13
323.8x9.53
355.6x9.53
406.4x9.53
457x9.53
508x9.53
559x9.53
610x9.53
660x9.53
711x9.53
762x9.53
813x9.53
864x9.53
914x9.53
965x9.53
1016x9.53
1067x9.53
1118x9.53
1168x9.53
1219x9.53
