Naddir M. Patel, P. Eng.

Some carbon steel alloys formerly considered resistant to stress corrosion cracking have been shown to be susceptible to it in recent years. The culprits are microalloying elements added to reduce heat-treating temperatures and times.

Many carbon steel items used in refineries and chemical processing plants that formerly were considered suitable for cold-weather service have been prone to brittle fracture failures at ambient temperatures in recent years. As such, ASME recently has changed the impact testing requirements for many spools, flanges, and piping products.

Think a Charpy impact test isn’t necessary? On some carbon steels used for low-temperature service, this test is needed to determine an alloy’s resistance to brittle fracture.