Na Septemba 17, 2021, Ngalaba Azụmaahịa nke US wepụtara ọkwa na a ga-emecha nyocha ikpeazụ nke ihe eji etinye ọkpọkọ carbon steel butt-welded (CarbonSteelButt-WeldPipeFittings) nke e si China, Taiwan, Brazil, Japan na Thailand bubata. Ọ bụrụ na a kagbuo mpụ ahụ Ọrụ mgbochi ịtụfu ihe n'okwu a ga-eme ka a tụfuo ngwaahịa ndị metụtara ikpe ahụ na China na ọnụego ịtụfu ihe nke 182.90% ma ọ bụ ihe omume nke ikpe ahụ, ọnụego ịtụfu ihe nke ngwaahịa ndị metụtara ikpe ahụ na China ga-aga n'ihu ma ọ bụ mee, ịtụfu ihe nke ngwaahịa ndị metụtara ikpe ahụ ga-aga n'ihu ma ọ bụ mee na ọnụego ịtụfu ihe nke 87.30% na 52.25%. Ịtụfu ihe nke ngwaahịa ndị metụtara ikpe ahụ gara n'ihu ma ọ bụ mee na ọnụego ịtụfu ihe nke 65.81%, ọnụego ịtụfu ihe nke ngwaahịa ndị metụtara na Thailand gara n'ihu ma ọ bụ mee na ọnụego ịtụfu ihe nke 52.60%. Ọ bụ 7307.93.30.

Na Disemba 12, 1986, mba Amerịka tinyere iwu megide ịtụfu ihe n'elu ọkpọkọ ígwè carbon nke sitere na Brazil na Taiwan, China. Na Febụwarị 10, 1987, mba Amerịka tinyere iwu megide ịtụfu ihe n'elu ọkpọkọ ígwè carbon nke sitere na Japan. Na Julaị 6, 1992, mba Amerịka tinyere iwu megide ịtụfu ihe n'elu ọkpọkọ ígwè carbon nke malitere na China na Thailand. Kemgbe ahụ, mba Amerịka emeela nyocha ugboro anọ gbasara etu anwụ si ada, na Jenụwarị 6, 2000, Nọvemba 21, 2005, Eprel 15, 2011, na Ọgọst 23, 2011. E mere nkwenye na ọkwa ahụ ugboro anọ. Na Julaị 1, 2021, Ngalaba Azụmahịa nke mba Amerịka wepụtara nyocha gbasara nyocha nke ise megide ịtụfu ihe n'elu ọkpọkọ ígwè carbon nke sitere na China, Taiwan, Brazil, Japan na Thailand.