Every project engineer and owner anticipate news of a tight line, ready to effectively serve its intended purpose.
Design
Hydro testing a new water line essentially begins during the design phase.
Understanding testing factors during design will enable the water professional to prepare for obstacles that may arise during the testing process.
Test requirements are set by considering the following:
- Flow/volume demands
- Size and length of pipe
- Total overall difference from the low to highest elevations
- Changes in elevation or “high spots.”
- The hydrostatic test parameters must be clearly defined during the design phase and stated in the project specifications.
- Guidelines set forth in the AWWA M41 Manual and the ANSI/AWWA C600 Standard are as follows:
“Test pressure shall be 1.25 times the operating pressure. Duration of the test is two hours. Special consideration must also be given when multiple piping products are used.”
A test pressure of 300 psi will be detrimental to weak materials, such as polyvinyl chloride (PVC) rated at 125 psi, which also does not have a safety factor of 2 and surge allowance of 100 psi included in the design,
compared to the stronger ductile iron that does.
Any material not designed for the specific pressures should not be used and should be isolated from any section of a line to be tested at higher pressures.
HOW WE CAN HELP YOU.
Complimentary on-site pressure test services are provided upon request by OFIMES TECHNOLOGY Inspection engineers to ensure product line tightness and effective project delivery to meet statutory standard requirements.
We also ensure that observations and recommendations are recorded as a report to help effective use of pipelines.
Hydrostatic Testing Procedures.
ANSI/AWWA C600 Installation Guide for Ductile-Iron Mains and Their Appurtenances.
WARNING: The testing methods described in this section are for water-pressure testing only. These procedures should not be applied for air-pressure testing because of the serious safety hazards involved with compressed air.
Also, pipelines intended for buried service should generally be tested with the backfill in place.
- Steps to Follow
- Slow fill the line. This will enhance the probability of removing aII air from the conduit.
- Fill the line at the lowest possible location while providing an air release at the highest location. Multiple air release locations may be provided due to the contour of the line.
- Practice patience. Allowing all the air to vent and adequate time for any water absorption in the cement lining are beneficial.
- The test pump is to be connected at the lowest point of the line.
- Prime the pump to remove all air prior to engagement with the line.
- The pressure gauge is to be connected to the pipe at the lowest location. *Reminder – connect the gauge to the pipe, not the pump.
- The pump should be isolated from the line during the actual test period.
- All head pressure will thus be included in the reading on the gauge.
- It is important to isolate the new line for pressure testing as well as allowing the new line to be properly chlorinated and bacteria tested prior to connection with a service line.
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