Ball valves act as on-off systems intended to control liquid flow. They have a hollow interior with a pivoting ball and are often commissioned for large and complex piping systems. To ensure that the valve performs optimally from its installation date to the end of its lifecycle, a series of proactive steps are taken. Testing and commissioning are quality-oriented processes for achieving, verifying, and documenting that the performance of applications and assemblies meet defined objectives and criteria.
Valve World Americas spoke with Robert Dinger, Production Manager and Field Service Manager at Industrial Standard Valve, concerning the necessary steps required to adequately commission ball valves.
By KCI Editorial
Installation of Ball Vales: Planning for Commission
Prior to commissioning a valve, it is important that the pressure, temperature, and material data sheet of the valve be compared to the actual operating conditions in the piping system; this is to ensure that the valve can withstand the loads occurring in the system. Once the specifications have been verified the valve can be installed. “The installation of a ball valve is fairly straightforward,” explained Dinger. “Depending on whether it is a flange or welded valve, it is simply a matter of putting the valve in place, inserting the bolts and nuts, and tightening – or welding if it is a welded valve.”
Once the valve has been installed, there are a few guidelines that must be followed.
- The using temperature and pressure conditions of valve should not exceed the maximum limited temperature and pressure.
- When the valve is used in the pipeline, it should be fully open or fully closed. It should not remain in the semi-closed or half-open state long term as it can affect the valves ability to seal.
The Basics of Commissioning
“Ball Valve commissioning is an inspection process to gain confidence that the valves will operate as required after installation and hydro testing. This process is used to help identify if any damage has been done to the valve after leaving the valve supplier. Damage to the valve internals (ball and seat) could have occurred during transit, storage, welding, or hydro testing and would affect the valve’s ability to seal and or operate,” explained Dinger.
The personnel performing the commissioning should be intimately familiar with the design of the valve and how the valve, and potential actuator, should function. Ensuring that inspectors receive the appropriate training required to operate the pipeline and have an active knowledge of the valve, are the essential pieces of knowhow needed to verify the integrity of the valve.
Commissioning should be done after the valve is installed and hydro tested before the end user product is introduced into the system. Once product is flowing through the pipeline it is very expensive to blow down, or isolate, the valve to assess if it will need to be removed or repaired.
The following steps are involved in commissioning a valve:
- Verify that valve will open and close.
• If it has an actuator, record the time it takes to open and close.
- Perform the ‘inside out’ test. This is to verify that the ball and seats will be able to hold pressure. To perform the test:
• Close valve. Once the valve is closed pressurize the valve body cavity through the drain fitting to 50 PSI with gage attached (Shop air or N2).
• Monitor gage to see if pressure holds for 30 minutes. If pressure drops more than 5 PSI then the valve is suspect and requires more investigation.
- Inject flush or valve lubricant into the seat injection ports. This pushes any remaining test fluid out of the ball seat area and lubricates the valve.
At the end of the commissioning, personnel must complete a report on each valve, including meticulous details from the process, such as valve and actuator serial numbers.
Post Installation-Pressure Verification and Preventative Methods
Once a valve has been installed and commissioned, end-users can verify that the application is able to seal the required pressure through a technique called double block and bleed. Dinger explained that, “Once the valve is closed, the drain fitting is opened to relieve the pressure in the body cavity which forces the media to stop. This technique can be used to verify that the valve is holding.”
Valves from the manufacturer are tested and given a test report to certify that they are capable of sealing and shutting off the flow. After the valves are shipped to the customer, they are often stored in a holding yard for an extended amount of time before being placed in use for an operation. It is during this holding period that that sand and other debris have the potential to get into the valves. The debris inside the piping is another significant threat to valves.
What Not to Do
Methods such as blast cleaning should be done with care, as this can be harsh on the internal parts of the valve. “Sand, welding rods, and dirt are just some of the many contaminants discovered in valve bodies. Minor valve seat leakage is often the result of scratches to the seating surfaces that are caused by these contaminants. If a minor leak persists, end users should inject the valve with flush and/ or sealant. It begins with using a light sealant and gradually increasing to a thicker sealant until the valve seals off. The valve stops may also need to be adjusted to achieve a functional seal.
End User Strategies to Protect the Valve
Protecting the valves during the hydro testing and installation phases must be prioritized. It may take a few months after the production of the valve to be used in an operation. There are valve covers in place to help keep external debris out of the inside of the valve. It is important to invest in the maintenance of a ball valve because it ensures the longevity of the device with few repairs, reduces the need for downtime and shutdowns, and results in cost savings. Proper installations, regular cleanings, valve lubrication, and routine inspections will ensure that the valve performs as it was intended, likely, for a longer period than the expected lifespan.