Yes, you can pressure test against a check valve, but it is not recommended for the main structural (shell) test of the piping. Check valves are rarely designed to withstand full hydrostatic test pressure on just one side of the seat and can easily leak or get damaged.
Learn the early (and late) warning signs of check valve failure, how to address them, and ways to prevent them from happening again.
ASME B31.
The test pressure shall not be less than 1.1 times the design pressure and shall not exceed the lower of 1.33 times the design pressure or the pressure that would produce a nominal pressure stress or longitudinal stress in excess of 90 % of the yield stress of any component at the test temperature.
Conclusion
Before performing hydrostatic testing or high-pressure washing of your system, you need to do one of three things: Remove the valve and install a blind flange, which will seal the system. Gag the valve so that it cannot be open by fluid.
Fill the valve with water or another testing fluid. Apply a pressure typically 1.5 times the valve's rated pressure (as per API 598 or ASME B16. 34 standards). Hold the pressure for a specific duration (often 1-5 minutes).
The 3% rule states that the non-recoverable pressure drop in the inlet piping to a PSV should be less than 3% of the valve set pressure. This guideline was developed as a way to ensure PSV stability and prevent valve chatter. Further, PSV relief capacities are based on the stagnation pressure at the nozzle inlet.
If the pressure differential falls below the cracking pressure (Figure 2) or there is back pressure (flow moving from the outlet to the inlet), the check valve will close. Check valves may have a gate, ball, diaphragm, or disc pressed against a valve seat to close the valve and block flow.
If you're wondering whether you can test or maintain your own backflow device, the short answer is: you can handle basic upkeep, but official testing and most repairs must be performed by a certified tester to stay compliant with local regulations.
Installing the valve in the wrong direction
The valve must allow water to flow forward only. Installing it backwards means it won't stop backflow and can cause leaks or damage.
Unless State or local codes specify more frequent inspection, temporary or portable pressurized equipment and systems must be inspected at intervals of not more than 6 months and permanent installations must be inspected at least annually. New pressure vessels.
In a hydrostatic test, the valve body is filled with testing fluid and then pressure is applied for a specified length of time. The valve is then inspected for any leakage. Learn more about valve leakage tests.
ISO 1167 is an internationally recognized standard that outlines the procedures for the hydrostatic pressure testing of thermoplastic pipes, fittings, and assemblies.
Causes of Failure:
Check valves operate automatically. Designed with internal components such as a disc, flap, or ball element, check valves open when the system pressure reaches a set threshold, known as the cracking pressure, and close automatically once the pressure drops and flow begins to reverse.
ASME valve standards are engineering codes that ensure valves operate safely and reliably in piping systems. Developed by the American Society of Mechanical Engineers, these standards define how valves must perform under pressure and temperature, how they are tested and what materials are acceptable.
Not all styles of check valves function properly or are suitable for vertical flow directions. When installing a check valve, a horizontal line is always preferred, because it takes gravity out of the equation. However, in real-world applications, the ideal situation is not always available.
No. In most plumbing applications, a check valve is not a safe or legal substitute for a backflow preventer. While both stop water from flowing backward, backflow preventers offer superior fail-safe mechanisms and are required by plumbing codes to protect drinking water from contamination.
Installation of the backflow preventer devices can be done by a licensed plumber but only certified Backflow Preventer Inspectors can certify the devices.
A backflow test ensures your prevention device is doing its job. During a backflow preventer inspection, a certified backflow tester will: Shut off the downstream water access. Measure pressure levels before and after the device. Inspect valves and seals.
Commercial backflow testing often costs more than residential testing. This is due to the complexity and size of commercial systems, which require more time and resources. Fees can vary substantially based on the type of property and the specific requirements of the test.
Yes, 90 psi is too high. Most residential plumbing codes recommend a maximum water pressure of 80 psi, with the ideal "sweet spot" being between 50 and 60 psi. Pressures above 80 psi put excessive stress on your pipes, fixtures, and appliances, leading to leaks and costly damage.
Symptoms of too much exhaust back pressure include sluggish acceleration, significant loss of high-speed power, poor fuel economy, and engine overheating. Your engine may also idle roughly, misfire, or stall completely when decelerating. In severe cases, the trapped heat and pressure can cause engine bay components to melt or blow out gaskets.
First, in most places, local laws will actually require that you use a licensed plumber with a backflow certification to install your backflow preventer. In addition, it's a more complicated task than it looks like, and installing one the wrong way could contaminate your clean water supply.