Reuters : Sinopec, CNPC skip Iran oil purchases for May to avoid U.S. sanctions China Petrochemical Corp (Sinopec Group) and China National Petroleum Corp (CNPC), the country’s top state-owned refiners, are skipping Iranian oil purchases for loading in May after Washington ended sanction waivers to turn up pressure on Tehran, three people with knowledge of the matter said. The United States has not renewed any exemptions from sanctions on Iran, taking a tougher line than expected on th