1110.pdf - Api Rp

Why does this matter? Because mills produce pipe with a minus tolerance (e.g., 0.01" thinner than spec). If you calculate your test pressure using the nominal thickness, you might accidentally overshoot the yield strength of the actual pipe by 3-4%.

Did you know a pipeline can fail a test even if it doesn't leak? RP 1110 warns about "growing" flaws. If you cycle the pressure up and down during a test (common when chasing a leak), you can actually drive a crack through the wall via fatigue—even if the peak pressure never exceeds the limit. Api Rp 1110.pdf

But in the era of high-frequency pressure cycling (thanks to renewable energy intermittency and batch switching), the 30-year-old assumptions in RP 1110 are being stress-tested like never before. Why does this matter