A tight spot

If a valve within a process plant fails for any reason, it will often mean part, or all, of the plant needs to shut down until a replacement valve can be fitted.

“This downtime can be extremely costly for plant owners so it is crucial the plant is operational again as quickly as possible,” says Geoff Rogers, head of Durapipe’s valve and flow control division.

But finding appropriate valve replacements is not necessarily a straightforward process.

“Specifying valves and flow control products for industrial process applications is a complex task and with so many options on the market, it can be a minefield trying to select the most appropriate,” says Rogers.

The company was recently approached by a customer in the hygiene solution sector in need of a replacement valve for a standard isolation application.

While the valve itself was not complicated, the configuration of the system was very complex and required a bespoke solution, says Rogers.

The existing system comprised a steel storage tank feeding into plastic pipework, with a flanged steel valve connecting the two, but with two different sized flanges and one a US standard and the other a UK standard, the client was struggling to find a product that would fit, he says.

After analysing the application and product requirements, Durapipe discovered that the size of the tank connection was 2” going down to 1½” diameter pipework in a very tight space, so not only was finding a solution for the specific space going to pose a challenge, but the system was also transferring three caustic solutions.

The three chemicals that would be passing through the valve; Sodium Hydroxide Pearl, Trisodium Nitrilo Triacetate and Tetrasodium Ethylenediamine Tetracetate are highly corrosive and so it was crucial to select a valve material that could safely convey the fluids, says Rogers.

Durapipe’s company chemist reviewed the specific chemicals and advised that a PVC-U valve needed to be used, as this material offers high chemical resistance, allowing the safe transfer of chemical concentrates without fear of corrosion.

Once the material had been selected, the valve technicians identified it was not necessary to have two flanges, or the flange connectors, as with the existing system.

As a result, the manufacturer built a bespoke PVC-U double union ball valve, with one flanged end, which fit the tight space constraints and was fully interchangeable with the existing system.

“Advice should always be sought when selecting valve and flow control products due to the complex nature of these systems,” says Rogers.

“Incorrect specifications are made almost daily, typically when customers specify products on price alone.

“Often, over-engineered valves can be sold for simple isolation processes, while flow control solutions that do not offer the accuracy levels required of the application could cause major problems in the process once installed.”

At another customer site, Durapipe received a request for two different sized diaphragm valves to control flow within the wastewater treatment plant’s process.

Durapipe investigated the application further before progressing the order. The team discovered that the valves were being used for chemical dosing and so a very precise flow measurement was required to avoid the dangers of too much chemical entering the system.

Rather than going down the diaphragm route, Durapipe recommended its VKR metering ball valve, which it says offers greater accuracy of flow monitoring data.

With a diaphragm valve, the flow increase is greater or smaller at either the start or the end of the opening cycle, however the VKR metering ball valve is linear throughout the full cycle.

Installing this valve also meant that the maximum flow could be increased by up to 37% compared with the diaphragm valve.

“Site visits are crucial to help clearly understand a client’s needs and so the Durapipe team regularly visits clients to see first-hand the process and application that is being discussed to ensure it can provide the most effective solution for individual projects,” says Rogers.

“No two days are ever the same. We face challenges on a daily basis and the team of specialists that operates the department is ready to react to any number of requests, often with very complex requirements and same-day deadlines.”