Zero maintenance valves reduce production costs, downtime
02 July 2019 | Web Article Number: ME201914932
WOUTER Witzel butterfly valves from AVK Southern Africa provided substantial cost-savings and reduced personnel requirements for KwaZulu Natal-based Umfolozi Sugar Mill (USM).
The savings enabled the company to redistribute finance to other plant instrumentation upgrades and negated the need for specialised valve maintenance personnel. This meant they were able to redeploy the workers to other plant maintenance tasks.
That’s according to a letter to AVK written by USM’s Technical Manager Ravi Vandayar in which he added that the Wouter Witzel DN700 butterfly valve, installed to regulate flow in one of the plant’s pan discharge applications, remained unaffected by the severity of the production process for more than six years – without any maintenance.
“The superior quality of the Wouter Witzel butterfly valves used in a pan discharge application at USM is noteworthy. Functioning under -95 kPa; at 75° C normal operating temperature and 110° C flash temperatures, the valve in question had a lifetime of more than six years with zero maintenance required. Others are still in service,” Vandayar wrote.
Keith Hedges, Business Development Manager, AVK Southern Africa said the Wouter Witzel valves differed from compting products in that its elastomer liner is fully vulcanised and bonded to the seal body. “This provides a 100% leak-free and vacuum-proof seal – both of which are exclusive to the Wouter Witzel brand,” Hedges said.
USM runs on a seasonal basis and maintenance, therefore, is conducted during off-season plant shutdown. The maintenance inspection subsequent to this valve installation included valve removal, damage inspection and functional scrutiny, which it passed with flying colours.
Hedges said this proved the valve’s durability compared to the wear and tear that competitor valves underwent.
Based on these findings, USM took the decision that future maintenance inspections for this specific valve would be reduced to a liner inspection and water test only. The water test is used to determine if there is any seal leakage, and none was ever found.
“This is in line with our, and Wouter Witzel’s, philosophy of ‘zero leakage, zero maintenance’. USM was sufficiently impressed with the inspection results that the plant began replacing its existing butterfly valves with Wouter Witzel valves, as and when required,” said Hedges.
These butterfly valves are heat-resistant, using NBR, EPDM or FPM rubber lining, which offer heat resistance up to 90, 110 or 200° C respectively. High-quality construction materials like ductile iron or cast steel on a single bodied valve; and a Rilsan, Epoxy or Halar coated duplex stainless steel disc contribute to enhanced durability.
The disc, centre to the valve’s design, is thinner than conventional valve discs which facilitates increased flow capacity and smaller actuators – if actuation is required. This contributes to increased pump efficiency resulting in lower power requirements.
This range of butterfly valves can be installed in the fully closed position, something which cannot be achieved with regular mounted valve seals. According to the company, the five-year warrantee is five times longer than the industry standard and is backed by a one-million-cycle guarantee.
“Compared to other butterfly valves in the market, ours last three to five times longer than any other similar product,” Hedges said.
The Wouter Witzel butterfly valve range is accredited by the American Petroleum Industry (API); Lloyd’s of London for marine applications; and the South African Gas Association (SAGAS). It also has numerous water-related certifications and is the only rubber-lined butterfly valve worldwide that has a fire-safe certification.
“These valves are suitable for the mining, steel, ship-building, oil & gas, desalination, HVAC, power plant and fire-fighting industries. In fact, they are specifically designed for high cycle and severe applications,” Hedges said.
Riaan Kloppers, Director – Industrial, AVK Southern Africa said the overall cost-saving experienced in plants using these valves is a lot more than it appears at face value.
“Some project engineers are of the opinion that, as valves required in a project constitute only between 1% and 3% of the cost, they needn’t pay too much consideration to this aspect of the project. They have not considered that valve failure results in downtime, a costly exercise for any plant.
“Considering high-quality, durable valves for these projects results in a significant financial saving over the medium- to long-term,” Kloppers said.