Ngwa ngwaahịa:
A na-eji ya na mmiri oyi na ụlọ ọrụ mmepụta ihe na nke obodo, mmiri ọkụ, kpo oku, ọkụ gas pipeline usoro, ọkụ-alụ ọgụ usoro anwụ na-efe efe na Central deployment pipeline, wdg.
Ọkọlọtọ nnabata:
| GB/T 19228 YB/T 4204 |
| GB/T 12771 QB/T 2467 |
| JIS G3448 |
| EN 10312-3S |
