How can you determine material compatibility with process fluids?

Process fluids must be compatible with the materials. We must ensure its compatibility in terms of pH, reactivity, rate of flow etc. Any deviations in these values will cause you cost and time both.

Upstream oil and gas industries considering two stages of process fluid identification to ensure the compatibility with the material we are going to select. The first stage is to identify the process fluid starting from temperature, pH, alkalinity, chloride, O2, CO2, H2S, elemental sulfur, organic acids, sand, etc. Then the corrosion model will be used to calculate the corrosion rate of CARBON STEEL along the design lifetime, if exposed to such process. When the corrosion rate is found to be too high, e.g: more than 5 mm/year, then the best decision to go into higher material (Stainless Steel or Corrosion Resistance Alloy) Second stage to review the compatibility of SS/CRA will be discussed in separate post.

in addition to identification of the process fluids, the service conditions such as temperature and pressure must be considered.

To determine material compatibility with process fluids, follow these steps: 1. Identify the process fluid. 2. List materials in contact. 3. Research chemical properties. 4. Consult compatibility charts. 5. Perform testing if necessary. 6. Ensure regulatory compliance. 7. Seek expert advice. 8. Document and monitor. 9. Consider long-term effects. 10. Plan maintenance and replacement. By systematically assessing these factors, you can select materials that won't react adversely with process fluids, ensuring safety and efficiency.

In the process of material selection the service conditions such as stresses applied, how this is applied and for how long, the service temperature and etc.

Again similar to previous points raised, in addition to fluid compatibility the service conditions needs to be taken into account and should not be excluded.

When commissioning laboratory tests it is important to simulate the fluid flow. Rotating cylinder tests are better than static coupons. You also need to test the welds to ensure that preferential weld corrosion will not be an issue.

The best material to be selected is the material, having the most cost-effective performance AND it has to be able to withstand its functionality from the day one until the end of equipment's design lifetime. The cost-effective performance evaluation shall cover OPEX, CAPEX and LPO.

At this point some other factors need to be considered. Firstly, availability, some materials have unacceptably long lead times. Secondly any issues around fabrication and repair, is this material simple to join and can any accidental damage be repaired in situ? Thirdly, Inspectability, some composite materials are difficult to inspect so assuring integrity after a period of service could be challenging. Finally, if the material is new you need to consider the risk associated with a lack of operational history.

The other factors to be considered on selecting the materials are but not limited to: 1. Material weight 2. Electrical or Heat conductivity 3. Easiness of installation (including weldable and formable characteristics) 4. Poisonous effects (especially for food and beverages industries) 5. Availability 6. Delivery lead time

Consider the role of Corrosion Inhibitors and Process Controls otherwise known as Integrity Operating Windows. An example of the latter is controlling the pH of cooling medium to minimise it's corrosivity.