How much sodium nitrite is required for a sodium nitrite lay-up?

In a sodium nitrite lay-up, the correct amount of sodium nitrite required is based on the concentration needed to effectively inhibit corrosion in the system. For a lay-up to be successful, the sodium nitrite concentration must be adequate to provide this protective effect.

The standard practice for preparing for a sodium nitrite lay-up is to use 10 pounds of sodium nitrite for every 1,000 gallons of feedwater. This concentration is usually sufficient to ensure that the environment within the system is adequately protected against corrosion during the lay-up period, as sodium nitrite is known for its ability to form a passivating layer on metal surfaces.

This established amount is also grounded in industry standards and practices; using significantly less may not provide sufficient protection, while using more could be wasteful and unnecessary. Therefore, option B is the correct choice and reflects the recommended procedure for sodium nitrite lay-ups.