Latest posts
-
How to build a pressure test ladder for a real segment
A test ladder sets the target pressures, hold times and acceptance criteria for a segment. The order the decisions must be made in, and what governs each.
-
Choosing a test medium: water, air or nitrogen
Medium selection caps what a pressure test can prove and changes the stored energy involved. What 49 CFR 192.503 and 195.306 permit, and the practical trade-offs.
-
Barlow’s formula and percent SMYS, worked plainly
Barlow’s formula relates pressure, diameter, wall thickness and hoop stress. How to use it to set a test pressure as a percentage of SMYS, with the constants.
-
The strength, leak and spike phases, and what each one proves
A pressure test does more than one job. Strength, leak and spike phases answer different questions at different pressures. What each proves, and why they are separate.
-
What a pressure test cannot prove
A successful hydrostatic test proves a margin at one moment. What it does not prove about slow leaks, pressure reversals and future condition.
-
Why a hydrostatic test runs four hours plus four hours
49 CFR 195.304 requires four continuous hours at 125 percent of MOP, plus four more at 110 percent when a line is not visually inspectable. Here is why.