🔍 Key Concepts

• Hydrostatic testing vs. pneumatic testing – which is safer for checking a potentially weakened pressure vessel? • What do Coast Guard regulations generally require when a defect may impair the safety of a pressure vessel? • The meaning of design pressure, maximum allowable working pressure (MAWP), and normal working pressure.

💭 Think About

• If a tank may be unsafe, would you want to test it with a compressible fluid (air/gas) or a non‑compressible fluid (water)? Why? • When testing for safety, do you usually test at, below, or above the normal working/allowable pressure? Think about safety margins. • Between design pressure, working pressure, and maximum allowable working pressure, which value usually represents the highest safe theoretical limit for calculation and testing?

✅ Before You Answer

• Be clear on the difference between hydrostatic (water) and pneumatic (air/gas) tests, and which one is inherently safer for a suspect vessel. • Confirm which pressure term – design pressure, working pressure, or maximum allowable working pressure (MAWP) – is typically used for regulatory test requirements on pressure vessels. • Check whether regulations call for a safety factor (like 1.5×) above the normal working or allowable pressure when testing after defects are found.