Recent summer maintenance programmes within industrial facilities should not have overlooked the importance of properly functioning valves, says Durapipe’s UK Fraser Higgins, who offers some pointers…
During the recent summer shutdown season when many industrial and wastewater processing facilities receive their annual inspection and maintenance programme, managers should have taken the opportunity to ensure products are still meeting the requirements of the application.
Valves, which are integral to the successful operation of chemical tanks, pumps and pipelines, must not be overlooked.
First check should always be to see if there are any leaks. Initial indications include build up on the valve ends, or around the handle.
It is important that any deposits, even if they are believed to be dirt, are thoroughly checked. The best way is to remove the valve from the system and inspect the seals, which are the most vulnerable areas. Valve designs vary and to ensure system integrity, it may be worth selecting one that has an increased number of seals, offering more protection against leaks.
Movement within a valve can also contribute to leakage. The key area is around the union nuts, which can become loose if there is aggressive vibration in the system. As an immediate fix, these can be tightened but changing to a valve with a locking mechanism that keeps the nut held steady should be considered if problems persist.
Consider any changes in the process – temperature, pressure or acidity – since the system was originally specified. It is crucial to check that equipment is still fit for purpose. Manufacturer technical support teams should always be consulted to provide advice on the most appropriate valves for use with new temperatures, fluids and pressures.
If plant and operation managers are experiencing frequent ‘jamming up’ of ball valves, it could be due to the sediment present in a process. You can fit sediment strainers into the line. The latest versions offer a range of filtration meshes, in different materials to avoid corrosion, while benefitting from easy maintenance. Alternatively, to avoid adding new elements, replace ball valves with a diaphragm valve, which works by a rubber seal.
A planned shutdown is the ideal time to look at flow control. Ball valves are the most common valve installed to control flow but have limitations with the accuracy of flow that can be. Changing to a metering ball valve that can offer a graduated positioning indicator will meet the requirements.
New age, new demands
Increasingly, industrial processes require valves to be operated remotely as a safety measure, to reduce downtime and increase efficiency. Actuators can be retrofitted to existing valves, minimising disruption to the plant operation
Finally, when reviewing the system, check the products comply with current legislation. This is of particular importance within water treatment applications, where utility companies are tightening their requirements. The discharge of trade effluent into the public sewer system is governed by the Water Industry Act 1991, with individual utilities setting the legal limits within their area. It is a criminal offence to breach these limits.
To ensure compliance, in line pH, conductivity, and ORP (redox) measurement devices can be installed. These can be simply introduced into an existing system by using an installation tee or a clamp saddle, depending on pipe size. For processes that already have these in place, it is important to check that there is no corrosion, software is up to date and that they have been programmed correctly.
Fraser Higgins is industrial product manager at Durapipe UK