Take care of valves in your projects
By Prof. B.P. Nansi
Valves appear to be a small item on your project equipment list. But valves play a vital role in your project. Remember that a chemical or refining or for that matter any industrial plant uses a large number of valves.
Take care of this small item. In the early stage of your project pay attention to the selection of valves. There are many valves around and they can be a source of various issues, problems and headaches. At the project stage, valves have to be stored, handled and managed well and later, during operations, valves pose problems like leakage, jamming and 'no-spare'.
So, select valves carefully.
Look at how many characteristics are considered before a valve is selected:
* Pressure temperature rating
* Material of body construction: Metal, plastic?
* Material of internals construction
* Operation: Manual, hydraulic, chain?
* Spindle design: Extended?
* End connections
The fact is that there are many selection parameters and they generate considerable inventory of parts and valves. Due to the variation in type, size, material etc., the inventory management becomes a task by itself.
Other aspects of valves needing your attention are: Location of a valve in the pipeline and any special design.
That is not all. Another consideration deciding the type, size, material etc., is the fluid in the pipeline. The fluid can be liquid, gas or solid or any combination of these three. Then there are the corrosion and erosion properties of the fluid. So that is another opportunity to increase the operation, maintenance and inventory issues.
One more source: Some valves are required to be tightly shut off. No fluid should 'leak' through the gate. That is because the downstream process cannot tolerate any presence of the fluid. Valves in such a duty need extra care, attention and maintenance.
One more point: Are you selecting a special valve; for example, an angle valve? Be careful. When you use an angle valve, the fluid takes a 900 turn after passing through the valve. An angle valve is a valve-cum-elbow. This sounds fantastic, but then that valve is a special item. Special items require special attention, need more maintenance and generate exclusive inventory. If there is no pressing need to have such a valve, just be happy with a conventional valve and an elbow.
Then there is the installation aspect. Pay attention to the location in the pipeline where a valve is installed. The access to valves for operation and, for maintenance and replacement, plays a decisive role in making operation people's life easy or difficult. In one assignment, the owner's project manager instructed us for some particular valves to be installed away from the operators and at a higher position. His argument: "The valves are not required to be operated frequently anyway. Then why install them near the operator's working area and at lower height?" We installed away and a little high in the pipeline.
Now the location of a valve in a pipeline is a subjective matter. If you ask two engineers you will get three recommendations. When that plant started, the operation people complained that the particular valves were located inconveniently. "Valves must be accessible immediately regardless how frequent the operation," was their argument.
So take care of valves in your project. Ensure that at the project stage itself the valves selection and installation is done judiciously. Target for easy operation and maintenance and minimum inventory.
(Prof. Nansi worked for 21 years with Tata Consulting Engineers. He can be contacted at bp.nansi@-projectsmonitor.com)
Take care of valves in your projects