According to the latest announcement of The International Trade Administration Commission of South Africa, since July 24, 2020, South Africa has launched the 3 phases of ad valorem safeguard measures against certain imported screws, bolts, and hexagonal nuts of iron and steel from all countries (except for some developing countries such as Brazil, Mexico, Russia, Indonesia, Thailand, Turkey, Vietnam, etc.), effective for 3 years. The HS codes of products involved are: 7318.15.41, 7318.15.42, 7318.16.30). Taiwan will be also influenced by the measures.

Below are the specific ad valorem duties for the 3 phases:
Phase one: 54.04% (07/24/2020-07/23/2021)
Phase two: 52.04% (07/24/2021-07/23/2022)
Phase three: 50.04% (07/24/2022-07/23/2023)

Source: fastener world