Editor's Choice

Valves for severe service

January 2024 Editor's Choice Valves, Actuators & Pump Control

Valve specialist, Valve & Automation (V&A) supplies total valve and control solutions to a wide range of key process industries across southern Africa. Chemicals, and pulp and paper are top of its list of industries with demanding process conditions, but the company also supports the mining and minerals, sugar, steel, power generation, and refining industries with manual valves, on/off valves, control valves and allied equipment. Key customers for V&A are Air Liquide, Anglo American, Sasol, Sappi, and Mondi.


V&A, together with its global partners, has a long history of working with chemical, petrochemical, and synthetic fuel companies. Conditions in these industries vary from aggressive chemical handling to extreme pressures and temperatures. In addition, production and engineering managers must reduce emissions, while meeting the demands for increased plant safety, and also reduce plant maintenance and production costs. This is a tall order, but V&A; can help them rise to these challenges.

V&A; regularly supplies companies like Sasol Chemical Industries, Sasol Synfuels, Sappi Chemical Cellulose, and Mondi to help their production plants meet their core objectives. The company’s solutions range from fully-lined pumps and valves and triple offset rotary process valves through to emergency shutdown valves and PST. Both NAF rotary control valves and Stafsjö knife gate valves are designed for applications with abrasive slurries.

Pulp and paper

V&A; also has extensive experience in the pulp and paper industry, together with global valve companies like Stafsjö. It regularly supplies equipment to major players such as Mondi Business Papers, Sappi Chemical Cellulose, Sappi Southern Africa, Sappi Fine Papers, mPact, and Nampak for processes that include digestion, recovery, bleaching, and causticising.

Sappi has awarded V&A; major contracts for manual and control valves for various projects, as has Mondi for other major projects. Significant contracts have also been awarded for pump protection systems by Sulzer and KSB for Eskom power stations.


V&A; also provides solutions to this tough industry, where most valves do not last more than a few weeks with abrasive slurries. Machinery and plant must be capable of dealing with media with a high volume of solids, abrasive material, corrosive chemicals, and high velocities. Engineers and plant operators must be able to have complete control over their operation, and select pipeline equipment that is reliable and able to withstand these harsh conditions. Linear and rotary valves must be able to operate for long periods without jamming or clogging. Replacement of parts and routine maintenance must be done quickly and easily to reduce downtime and the impact on production. To meet these demands, V&A; can offer long-lasting Stafsjö MV standard, HG through going, and SLH-SLX high-pressure knife gate valves for slurries. Fully-lined Richter butterfly and ball valves are ideally suited for chemical applications within mineral separation.

High-performance knife gate valves

Knife gate valves work in the harshest environments, typically having a sharpened blade to cut through heavy liquids. They are perfect for isolation of liquids containing abrasive solids or fibres, slurries, or viscous, corrosive media. The valves have a minimised pressure drop in fully open position, they are easy to actuate, they have a relatively low weight, and they are cost-effective.

One of V&A’s top suppliers is Stafsjö. Headquartered in Stavsjö, Sweden, the company manufactures high-performance knife gate valves for reliable and long-lasting operation in demanding industrial processes throughout the world. Stafsjö has a long history that is rich in tradition. The story began in 1666 with the manufacture of cannons, which lasted for almost 200 years. As testimony to the durability of Stafsjö products, one of these cannons can be found in Hout Bay. Weighing five tons, it was cast in 1780 in Sweden. According to the Cannon Association of SA, it was recently fired, to mark the coronation of King Charles III, using a kilogram of gunpowder.

In 1928, Stafsjö introduced its first knife gate valves. Today the company focuses on process technology and has positioned itself in the paper and pulp industry. The company manufactures approximately 20 000 knife gate valves a year, with more than 80% destined for export.

Here are two case studies highlighting the company’s excellence in this industry.

World record tons of pulp

The region west of Sao Paulo in Brazil has become the world’s largest producer of cellulose. With an annual capacity of 1,8 million tons of bleached eucalyptus hardwood pulp, Eldorado Brazil’s Três Lagoas mill is the largest single-line pulp mill in the world.

The mill needed to develop a large scale, state-of-the art plant with high productivity and low conversion costs, meeting all sustainability requirements. “For technical excellence and quality, Stafsjö was a natural choice,” says chief engineer Vesa Romppanen from Andritz, the key supplier for the new pulp line. He specified and purchased the Stafsjö MV DN 1400/56 valve for high-density bleach stock and tower isolation. “We needed a tailor-made valve,” said Romppanen. “We knew from past experience that we could rely on the team at Stafsjö. Together we found the solution for this project, a customised 3,5 ton MV valve with purge ports close to the seat, capable of handling really high pulp concentrations. This was a huge project with many challenges, extreme pressures, and large amounts of pulp and water per second.”

Everything has worked like clockwork since. A year after, Eldorado was producing a world-record 5000 tons in a single day. The facility is also contributing to the local population, providing jobs for about 25 000 people.

Breaking new ground

China is not only a huge and important market, it is also home to industries that require very large components. Stafsjö was confronted with a massive challenge. The end customer was a giant within the Chinese business world and one of the largest producers of pulp and paper in the industry.

The company demanded high quality at a reasonable price, with near-zero emission rates and minimal consumption of resources, while still preserving growth and productivity. The blow tank tower was 32 metres high, with a correspondingly high pressure. The bottom valve had to hold this tightly and process highly concentrated pulp. The environment was aggressive and exposed. There was no knife gate valve available with such large dimensions. The result was one of the largest valves in Stafsjö’s history, tailored to meet the customer’s requirements. “This was a demanding project, and we were breaking new ground,” says key account manager for pulp and paper in China, Su Chuansheng.

Think globally, act locally

Operations director of V&A, Greg Woolfuth sums it up: “Our customers can trust us with world-class products and unmatched application knowledge, so that they can be relieved from the burden of worrying about manual and control valves, and can focus on their core business objectives more effectively. Our valve repair facilities in Secunda and Durban assist in extending the valve service life, thereby reducing the cost of ownership. We want to help them add value to their production process, so they are more competitive in a global market.”


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