NACE has published several standards related to dissolved oxygen in oil and gas operations, including:

• NACE MR0175/ISO 15156: Petroleum, petrochemical and natural gas industries - Materials for use in H2S-containing environments in oil and gas production. Part 2, Section 7.2.6, which addresses the control of corrosion caused by oxygen: "Where oxygen is known or suspected to be present in the environment of the equipment, its concentration should be reduced as far as possible. If the oxygen concentration in water cannot be controlled effectively, then materials resistant to oxygen corrosion should be selected. The maximum acceptable oxygen concentration in the water is 20 ppb."
• NACE SP0490: Control of External Corrosion on Underground or Submerged Metallic Piping Systems. In Section 4.1.3.1, which discusses the requirements for controlling oxygen content in refinery feedwater: "The recommended maximum oxygen concentration for feedwater to the boilers should be 7 ppb (0.007 mg/L) or less. A maximum limit of 20 ppb (0.02 mg/L) is generally used as the acceptable limit for oxygen in water for most refinery services."
• NACE Standard RP0193-2001, which states: "The dissolved oxygen content of the water in contact with the tank bottom shall be controlled to a maximum of 20 ppb to prevent corrosion of the tank bottom."

These standards provide guidance on acceptable levels of dissolved oxygen to prevent corrosion in oil and gas production, processing, and transportation facilities.

Similarly, API Recommended Practice 651, "Cathodic Protection of Aboveground Petroleum Storage Tanks," also recommends maintaining DO levels below 20 ppb.

The permissible limit of